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Dystonia

MedGen UID:
3940
Concept ID:
C0013421
Sign or Symptom
Synonyms: Dystonic disease; Dystonic movements
 
HPO: HP:0001332
OMIM® Phenotypic series: PS128100

Definition

An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk. [from HPO]

Conditions with this feature

Ataxia-telangiectasia syndrome
MedGen UID:
439
Concept ID:
C0004135
Disease or Syndrome
Ataxia-telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar ataxia, telangiectases, immune defects, and a predisposition to malignancy. Chromosomal breakage is a feature. AT cells are abnormally sensitive to killing by ionizing radiation (IR), and abnormally resistant to inhibition of DNA synthesis by ionizing radiation. The latter trait has been used to identify complementation groups for the classic form of the disease (Jaspers et al., 1988). At least 4 of these (A, C, D, and E) map to chromosome 11q23 (Sanal et al., 1990) and are associated with mutations in the ATM gene.
Pigmentary pallidal degeneration
MedGen UID:
6708
Concept ID:
C0018523
Disease or Syndrome
Pantothenate kinase-associated neurodegeneration (PKAN) is a type of neurodegeneration with brain iron accumulation (NBIA). The phenotypic spectrum of PKAN includes classic PKAN and atypical PKAN. Classic PKAN is characterized by early childhood onset of progressive dystonia, dysarthria, rigidity, and choreoathetosis. Pigmentary retinal degeneration is common. Atypical PKAN is characterized by later onset (age >10 years), prominent speech defects, psychiatric disturbances, and more gradual progression of disease.
Wilson disease
MedGen UID:
42426
Concept ID:
C0019202
Disease or Syndrome
Wilson disease is a disorder of copper metabolism that can present with hepatic, neurologic, or psychiatric disturbances, or a combination of these, in individuals ranging from age three years to older than 50 years; symptoms vary among and within families. Liver disease includes recurrent jaundice, simple acute self-limited hepatitis-like illness, autoimmune-type hepatitis, fulminant hepatic failure, or chronic liver disease. Neurologic presentations include movement disorders (tremors, poor coordination, loss of fine-motor control, chorea, choreoathetosis) or rigid dystonia (mask-like facies, rigidity, gait disturbance, pseudobulbar involvement). Psychiatric disturbance includes depression, neurotic behaviors, disorganization of personality, and, occasionally, intellectual deterioration. Kayser-Fleischer rings, frequently present, result from copper deposition in Descemet's membrane of the cornea and reflect a high degree of copper storage in the body.
Leigh syndrome
MedGen UID:
44095
Concept ID:
C0023264
Disease or Syndrome
Leigh syndrome is a clinically and genetically heterogeneous disorder resulting from defective mitochondrial energy generation. It most commonly presents as a progressive and severe neurodegenerative disorder with onset within the first months or years of life, and may result in early death. Affected individuals usually show global developmental delay or developmental regression, hypotonia, ataxia, dystonia, and ophthalmologic abnormalities, such as nystagmus or optic atrophy. The neurologic features are associated with the classic findings of T2-weighted hyperintensities in the basal ganglia and/or brainstem on brain imaging. Leigh syndrome can also have detrimental multisystemic affects on the cardiac, hepatic, gastrointestinal, and renal organs. Biochemical studies in patients with Leigh syndrome tend to show increased lactate and abnormalities of mitochondrial oxidative phosphorylation (summary by Lake et al., 2015). Genetic Heterogeneity of Leigh Syndrome Leigh syndrome may be a clinical presentation of a primary deficiency caused by genes in any of the mitochondrial respiratory chain complexes: complex I deficiency (see 252010), complex II deficiency (see 252011), complex III deficiency (see 124000), complex IV deficiency (cytochrome c oxidase; see 220110), and complex V deficiency (see 604273) (summary by Lake et al., 2015). Mutations in genes encoding mitochondrial tRNA proteins have also been identified in patients with Leigh syndrome: see MTTV (590105), MTTK (590060), MTTW (590095), and MTTL1 (590050). Leigh syndrome may also be caused by mutations in components of the pyruvate dehydrogenase complex (e.g., DLD, 238331 and PDHA1, 300502). Deficiency of coenzyme Q10 (607426) can present as Leigh syndrome. Some forms of combined oxidative phosphorylation deficiency can present as Leigh syndrome (see, e.g., 617664).
Lesch-Nyhan syndrome
MedGen UID:
9721
Concept ID:
C0023374
Disease or Syndrome
HPRT1 disorders, caused by deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGprt), are typically associated with clinical evidence for overproduction of uric acid (hyperuricemia, nephrolithiasis, and/or gouty arthritis) and varying degrees of neurologic and/or behavioral problems. Historically, three phenotypes were identified in the spectrum of HPRT1 disorders: Lesch-Nyhan disease (LND) at the most severe end with motor dysfunction resembling severe cerebral palsy, intellectual disability, and self-injurious behavior; HPRT1-related neurologic dysfunction (HND) in the intermediate range with similar but fewer severe neurologic findings than LND and no self-injurious behavior; and HPRT1-related hyperuricemia (HRH) at the mild end without overt neurologic deficits. It is now recognized that these neurobehavioral phenotypes cluster along a continuum from severe to mild.
Metachromatic leukodystrophy
MedGen UID:
6071
Concept ID:
C0023522
Disease or Syndrome
Arylsulfatase A deficiency (also known as metachromatic leukodystrophy or MLD) is characterized by three clinical subtypes: late-infantile MLD, juvenile MLD, and adult MLD. Age of onset within a family is usually similar. The disease course may be from several years in the late-infantile-onset form to decades in the juvenile- and adult-onset forms. Late-infantile MLD. Onset is before age 30 months. Typical presenting findings include weakness, hypotonia, clumsiness, frequent falls, toe walking, and dysarthria. As the disease progresses, language, cognitive, and gross and fine motor skills regress. Later signs include spasticity, pain, seizures, and compromised vision and hearing. In the final stages, children have tonic spasms, decerebrate posturing, and general unawareness of their surroundings. Juvenile MLD. Onset is between age 30 months and 16 years. Initial manifestations include decline in school performance and emergence of behavioral problems, followed by gait disturbances. Progression is similar to but slower than in the late-infantile form. Adult MLD. Onset occurs after age 16 years, sometimes not until the fourth or fifth decade. Initial signs can include problems in school or job performance, personality changes, emotional lability, or psychosis; in others, neurologic symptoms (weakness and loss of coordination progressing to spasticity and incontinence) or seizures initially predominate. Peripheral neuropathy is common. Disease course is variable – with periods of stability interspersed with periods of decline – and may extend over two to three decades. The final stage is similar to earlier-onset forms.
Azorean disease
MedGen UID:
9841
Concept ID:
C0024408
Disease or Syndrome
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is characterized by progressive cerebellar ataxia and variable findings including pyramidal signs, a dystonic-rigid extrapyramidal syndrome, significant peripheral amyotrophy and generalized areflexia, progressive external ophthalmoplegia, action-induced facial and lingual fasciculations, and bulging eyes. Neurologic findings tend to evolve as the disorder progresses.
Pyruvate dehydrogenase complex deficiency
MedGen UID:
19610
Concept ID:
C0034345
Disease or Syndrome
Pyruvate dehydrogenase deficiency is characterized by the buildup of a chemical called lactic acid in the body and a variety of neurological problems. Signs and symptoms of this condition usually first appear shortly after birth, and they can vary widely among affected individuals. The most common feature is a potentially life-threatening buildup of lactic acid (lactic acidosis), which can cause nausea, vomiting, severe breathing problems, and an abnormal heartbeat. People with pyruvate dehydrogenase deficiency usually have neurological problems as well. Most have delayed development of mental abilities and motor skills such as sitting and walking. Other neurological problems can include intellectual disability, seizures, weak muscle tone (hypotonia), poor coordination, and difficulty walking. Some affected individuals have abnormal brain structures, such as underdevelopment of the tissue connecting the left and right halves of the brain (corpus callosum), wasting away (atrophy) of the exterior part of the brain known as the cerebral cortex, or patches of damaged tissue (lesions) on some parts of the brain. Because of the severe health effects, many individuals with pyruvate dehydrogenase deficiency do not survive past childhood, although some may live into adolescence or adulthood.
Rett syndrome
MedGen UID:
48441
Concept ID:
C0035372
Disease or Syndrome
The spectrum of MECP2-related phenotypes in females ranges from classic Rett syndrome to variant Rett syndrome with a broader clinical phenotype (either milder or more severe than classic Rett syndrome) to mild learning disabilities; the spectrum in males ranges from severe neonatal encephalopathy to pyramidal signs, parkinsonism, and macroorchidism (PPM-X) syndrome to severe syndromic/nonsyndromic intellectual disability. Females: Classic Rett syndrome, a progressive neurodevelopmental disorder primarily affecting girls, is characterized by apparently normal psychomotor development during the first six to 18 months of life, followed by a short period of developmental stagnation, then rapid regression in language and motor skills, followed by long-term stability. During the phase of rapid regression, repetitive, stereotypic hand movements replace purposeful hand use. Additional findings include fits of screaming and inconsolable crying, autistic features, panic-like attacks, bruxism, episodic apnea and/or hyperpnea, gait ataxia and apraxia, tremors, seizures, and acquired microcephaly. Males: Severe neonatal-onset encephalopathy, the most common phenotype in affected males, is characterized by a relentless clinical course that follows a metabolic-degenerative type of pattern, abnormal tone, involuntary movements, severe seizures, and breathing abnormalities. Death often occurs before age two years.
Pelizaeus-Merzbacher disease
MedGen UID:
61440
Concept ID:
C0205711
Disease or Syndrome
PLP1 disorders of central nervous system myelin formation include a range of phenotypes from Pelizaeus-Merzbacher disease (PMD) to spastic paraplegia 2 (SPG2). PMD typically manifests in infancy or early childhood with nystagmus, hypotonia, and cognitive impairment; the findings progress to severe spasticity and ataxia. Life span is shortened. SPG2 manifests as spastic paraparesis with or without CNS involvement and usually normal life span. Intrafamilial variation of phenotypes can be observed, but the signs are usually fairly consistent within families. Heterozygous females may manifest mild-to-moderate signs of the disease.
Mucolipidosis type IV
MedGen UID:
68663
Concept ID:
C0238286
Disease or Syndrome
Mucolipidosis IV (MLIV) is an ultra-rare lysosomal storage disorder characterized by severe psychomotor delay, progressive visual impairment, and achlorhydria. Individuals with MLIV typically present by the end of the first year of life with delayed developmental milestones (due to a developmental brain abnormality) and impaired vision (resulting from a combination of corneal clouding and retinal degeneration). By adolescence, all individuals with MLIV have severe visual impairment. A neurodegenerative component of MLIV has become more widely appreciated, with the majority of individuals demonstrating progressive spastic quadriparesis and loss of psychomotor skills starting in the second decade of life. About 5% of individuals have atypical MLIV, manifesting with less severe psychomotor impairment, but still exhibiting progressive retinal degeneration and achlorhydria.
Juvenile paralysis agitans of Hunt
MedGen UID:
66768
Concept ID:
C0238344
Disease or Syndrome
GM1 gangliosidosis type 3
MedGen UID:
78655
Concept ID:
C0268273
Disease or Syndrome
GLB1-related disorders comprise two phenotypically distinct lysosomal storage disorders: GM1 gangliosidosis and mucopolysaccharidosis type IVB (MPS IVB). The phenotype of GM1 gangliosidosis constitutes a spectrum ranging from severe (infantile) to intermediate (late-infantile and juvenile) to mild (chronic/adult). Type I (infantile) GM1 gangliosidosis begins before age 12 months. Prenatal manifestations may include nonimmune hydrops fetalis, intrauterine growth restriction, and placental vacuolization; congenital dermal melanocytosis (Mongolian spots) may be observed. Macular cherry-red spot is detected on eye exam. Progressive central nervous system dysfunction leads to spasticity and rapid regression; blindness, deafness, decerebrate rigidity, seizures, feeding difficulties, and oral secretions are observed. Life expectancy is two to three years. Type II can be subdivided into the late-infantile (onset age 1-3 years) and juvenile (onset age 3-10 years) phenotypes. Central nervous system dysfunction manifests as progressive cognitive, motor, and speech decline as measured by psychometric testing. There may be mild corneal clouding, hepatosplenomegaly, and/or cardiomyopathy; the typical course is characterized by progressive neurologic decline, progressive skeletal disease in some individuals (including kyphosis and avascular necrosis of the femoral heads), and progressive feeding difficulties leading to aspiration risk. Type III begins in late childhood to the third decade with generalized dystonia leading to unsteady gait and speech disturbance followed by extrapyramidal signs including akinetic-rigid parkinsonism. Cardiomyopathy develops in some and skeletal involvement occurs in most. Intellectual impairment is common late in the disease with prognosis directly related to the degree of neurologic impairment. MPS IVB is characterized by skeletal dysplasia with specific findings of axial and appendicular dysostosis multiplex, short stature (below 15th centile in adults), kyphoscoliosis, coxa/genu valga, joint laxity, platyspondyly, and odontoid hypoplasia. First signs and symptoms may be apparent at birth. Bony involvement is progressive, with more than 84% of adults requiring ambulation aids; life span does not appear to be limited. Corneal clouding is detected in some individuals and cardiac valvular disease may develop.
Tay-Sachs disease, variant AB
MedGen UID:
78657
Concept ID:
C0268275
Disease or Syndrome
The GM2-gangliosidoses are a group of disorders caused by excessive accumulation of ganglioside GM2 and related glycolipids in the lysosomes, mainly of neuronal cells. GM2-gangliosidosis AB variant is characterized by normal hexosaminidase A (HEXA; 606869) and hexosaminidase B (HEXB; 606873) but the inability to form a functional GM2 activator complex. The clinical and biochemical phenotype of the AB variant is very similar to that of classic Tay-Sachs disease (see 272800) (Gravel et al., 2001).
Dihydropteridine reductase deficiency
MedGen UID:
75682
Concept ID:
C0268465
Disease or Syndrome
Tetrahydrobiopterin deficiency is a rare disorder characterized by a shortage (deficiency) of a molecule called tetrahydrobiopterin or BH4. This condition alters the levels of several substances in the body, including phenylalanine. Phenylalanine is a building block of proteins (an amino acid) that is obtained through the diet. It is found in foods that contain protein and in some artificial sweeteners. High levels of phenylalanine are present from early infancy in people with untreated tetrahydrobiopterin deficiency. This condition also alters the levels of chemicals called neurotransmitters, which transmit signals between nerve cells in the brain.\n\nInfants with tetrahydrobiopterin deficiency appear normal at birth, but medical problems ranging from mild to severe become apparent over time. Signs and symptoms of this condition can include intellectual disability, progressive problems with development, movement disorders, difficulty swallowing, seizures, behavioral problems, and an inability to control body temperature.
GTP cyclohydrolase I deficiency
MedGen UID:
75683
Concept ID:
C0268467
Disease or Syndrome
Infants with tetrahydrobiopterin deficiency appear normal at birth, but medical problems ranging from mild to severe become apparent over time. Signs and symptoms of this condition can include intellectual disability, progressive problems with development, movement disorders, difficulty swallowing, seizures, behavioral problems, and an inability to control body temperature.\n\nTetrahydrobiopterin deficiency is a rare disorder characterized by a shortage (deficiency) of a molecule called tetrahydrobiopterin or BH4. This condition alters the levels of several substances in the body, including phenylalanine. Phenylalanine is a building block of proteins (an amino acid) that is obtained through the diet. It is found in foods that contain protein and in some artificial sweeteners. High levels of phenylalanine are present from early infancy in people with untreated tetrahydrobiopterin deficiency. This condition also alters the levels of chemicals called neurotransmitters, which transmit signals between nerve cells in the brain.
Dopa-responsive dystonia due to sepiapterin reductase deficiency
MedGen UID:
120642
Concept ID:
C0268468
Disease or Syndrome
The phenotypic spectrum of sepiapterin reductase deficiency (SRD), which ranges from significant motor and cognitive deficits to only minimal findings, has not been completely elucidated. Clinical features in the majority of affected individuals include motor and speech delay, axial hypotonia, dystonia, weakness, and oculogyric crises; symptoms show diurnal fluctuation and sleep benefit. Other common features include parkinsonian signs (tremor, bradykinesia, masked facies, rigidity), limb hypertonia, hyperreflexia, intellectual disability, psychiatric and/or behavioral abnormalities, autonomic dysfunction, and sleep disturbances (hypersomnolence, difficulty initiating or maintaining sleep, and drowsiness). Most affected individuals have nonspecific features in infancy including developmental delays and axial hypotonia; other features develop over time.
Propionic acidemia
MedGen UID:
75694
Concept ID:
C0268579
Disease or Syndrome
The spectrum of propionic acidemia (PA) ranges from neonatal-onset to late-onset disease. Neonatal-onset PA, the most common form, is characterized by a healthy newborn with poor feeding and decreased arousal in the first few days of life, followed by progressive encephalopathy of unexplained origin. Without prompt diagnosis and management, this is followed by progressive encephalopathy manifesting as lethargy, seizures, or coma that can result in death. It is frequently accompanied by metabolic acidosis with anion gap, lactic acidosis, ketonuria, hypoglycemia, hyperammonemia, and cytopenias. Individuals with late-onset PA may remain asymptomatic and suffer a metabolic crisis under catabolic stress (e.g., illness, surgery, fasting) or may experience a more insidious onset with the development of multiorgan complications including vomiting, protein intolerance, failure to thrive, hypotonia, developmental delays or regression, movement disorders, or cardiomyopathy. Isolated cardiomyopathy can be observed on rare occasion in the absence of clinical metabolic decompensation or neurocognitive deficits. Manifestations of neonatal and late-onset PA over time can include growth impairment, intellectual disability, seizures, basal ganglia lesions, pancreatitis, and cardiomyopathy. Other rarely reported complications include optic atrophy, hearing loss, premature ovarian insufficiency, and chronic renal failure.
Glutaric aciduria, type 1
MedGen UID:
124337
Concept ID:
C0268595
Disease or Syndrome
The phenotypic spectrum of untreated glutaric acidemia type 1 (GA-1) ranges from the more common form (infantile-onset disease) to the less common form (later-onset disease – i.e., after age 6 years). Of note, the GA-1 phenotype can vary widely between untreated family members with the same genotype, primarily as a function of the age at which the first acute encephalopathic crisis occurred: three months to six years in infantile-onset GA-1 and after age six years in later-onset GA-1. Characteristically these crises result in acute bilateral striatal injury and subsequent complex movement disorders. In the era of newborn screening (NBS), the prompt initiation of treatment of asymptomatic infants detected by NBS means that most individuals who would have developed manifestations of either infantile-onset or later-onset GA-1 remain asymptomatic; however, they may be at increased risk for other manifestations (e.g., renal disease) that are becoming apparent as the understanding of the natural history of treated GA-1 continues to evolve.
Hepatic methionine adenosyltransferase deficiency
MedGen UID:
75700
Concept ID:
C0268621
Disease or Syndrome
Methionine adenosyltransferase deficiency is an inborn error of metabolism resulting in isolated hypermethioninemia. Most patients have no clinical abnormalities, although some with the autosomal recessive form have have neurologic abnormalities (Mudd et al., 2003; Kim et al., 2016).
Hypogonadism, diabetes mellitus, alopecia, mental retardation and electrocardiographic abnormalities
MedGen UID:
83337
Concept ID:
C0342286
Disease or Syndrome
Virtually all individuals with Woodhouse-Sakati syndrome (WSS) have the endocrine findings of hypogonadism (evident at puberty) and progressive childhood-onset hair thinning that often progresses to alopecia totalis in adulthood. More than half of individuals have the neurologic findings of progressive extrapyramidal movements (dystonic spasms with dystonic posturing with dysarthria and dysphagia), moderate bilateral postlingual sensorineural hearing loss, and mild intellectual disability. To date, more than 40 families (including 33 with a molecularly confirmed diagnosis) with a total of 88 affected individuals have been reported in the literature.
3-Methylglutaconic aciduria type 1
MedGen UID:
90994
Concept ID:
C0342727
Disease or Syndrome
3-methylglutaconyl-CoA hydratase deficiency is an inherited condition that causes neurological problems. Beginning in infancy to early childhood, children with this condition often have delayed development of mental and motor skills (psychomotor delay), speech delay, involuntary muscle cramping (dystonia), and spasms and weakness of the arms and legs (spastic quadriparesis). Affected individuals can also have optic atrophy, which is the breakdown (atrophy) of nerve cells that carry visual information from the eyes to the brain.\n\nIn some cases, signs and symptoms of 3-methylglutaconyl-CoA hydratase deficiency begin in adulthood, often in a person's twenties or thirties. These individuals have damage to a type of brain tissue called white matter (leukoencephalopathy). This damage likely contributes to progressive problems with speech (dysarthria), difficulty coordinating movements (ataxia), stiffness (spasticity), optic atrophy, and a decline in intellectual function (dementia).\n\nAffected individuals who show symptoms of 3-methylglutaconyl-CoA hydratase deficiency in childhood often go on to develop leukoencephalopathy and other neurological problems in adulthood.\n\nAll people with 3-methylglutaconyl-CoA hydratase deficiency accumulate large amounts of a substance called 3-methylglutaconic acid in their body fluids. As a result, they have elevated levels of acid in their blood (metabolic acidosis) and excrete large amounts of acid in their urine (aciduria). 3-methylglutaconyl-CoA hydratase deficiency is one of a group of metabolic disorders that can be diagnosed by the presence of increased levels 3-methylglutaconic acid in urine (3-methylglutaconic aciduria). People with 3-methylglutaconyl-CoA hydratase deficiency also have high urine levels of another acid called 3-methylglutaric acid.
Beta-hydroxyisobutyryl-CoA deacylase deficiency
MedGen UID:
83349
Concept ID:
C0342738
Disease or Syndrome
3-Hydroxyisobutyryl-CoA hydrolase deficiency (HIBCHD) is an autosomal recessive inborn error of metabolism characterized by severely delayed psychomotor development, neurodegeneration, increased lactic acid, and brain lesions in the basal ganglia (summary by Ferdinandusse et al., 2013).
Choreoacanthocytosis
MedGen UID:
98277
Concept ID:
C0393576
Disease or Syndrome
Chorea-acanthocytosis (ChAc) is characterized by a progressive movement disorder, cognitive and behavior changes, a myopathy that can be subclinical, and chronic hyperCKemia in serum. Although the disorder is named for acanthocytosis of the red blood cells, this feature is variable. The movement disorder is mostly limb chorea, but some individuals present with parkinsonism. Dystonia is common and affects the oral region and especially the tongue, causing dysarthria and serious dysphagia with resultant weight loss. Habitual tongue and lip biting are characteristic, as well as tongue protrusion dystonia. Progressive cognitive and behavioral changes resemble those in a frontal lobe syndrome. Seizures are observed in almost half of affected individuals and can be the initial manifestation. Myopathy results in progressive distal muscle wasting and weakness. Mean age of onset in ChAc is about 30 years, although ChAc can develop as early as the first decade or as late as the seventh decade. It runs a chronic progressive course and may lead to major disability within a few years. Life expectancy is reduced, with age of death ranging from 28 to 61 years.
Deletion of short arm of chromosome 18
MedGen UID:
96604
Concept ID:
C0432442
Disease or Syndrome
Monosomy 18p refers to a chromosomal disorder resulting from the deletion of all or part of the short arm of chromosome 18.
Filippi syndrome
MedGen UID:
163197
Concept ID:
C0795940
Disease or Syndrome
Filippi syndrome is characterized by short stature, microcephaly, syndactyly, intellectual disability, and facial dysmorphism consisting of bulging forehead, broad and prominent nasal bridge, and diminished alar flare. Common features include cryptorchidism, speech impairment, and clinodactyly of the fifth finger, Some patients exhibit visual disturbances, polydactyly, seizures, and/or ectodermal abnormalities, such as nail hypoplasia, long eyelashes, hirsutism, and microdontia (summary by Hussain et al., 2014).
Striatonigral degeneration infantile
MedGen UID:
167090
Concept ID:
C0795996
Disease or Syndrome
Bilateral striatal necrosis (BSN) encompasses a heterogeneous group of neurologic disorders with different causation. Familial infantile striatal degeneration is rare and can be inherited as an autosomal recessive or mitochondrial (see 500003) disorder. The familial form has an insidious onset and a slowly progressive course; the sporadic form is associated with acute systemic illness. Many features of BSN overlap with Leigh syndrome (256000) and certain metabolic disorders, including glutaric acidemia I (231670) and methylmalonic aciduria (251000). See also Aicardi-Goutieres syndrome (225750) (Mito et al., 1986; De Meirleir et al., 1995). Genetic Heterogeneity of Stiatonigral Degeneration Childhood-onset striatonigral degeneration (617054) is caused by mutation in the VAC14 gene (604632) on chromosome 16q22. See also adult-onset autosomal dominant striatal degeneration (ADSD; 609161), caused by mutation in the PDE8B gene (603390) on chromosome 5q13.
Deafness dystonia syndrome
MedGen UID:
162903
Concept ID:
C0796074
Disease or Syndrome
Males with deafness-dystonia-optic neuronopathy (DDON) syndrome have prelingual or postlingual sensorineural hearing impairment in early childhood, slowly progressive dystonia or ataxia in the teens, slowly progressive decreased visual acuity from optic atrophy beginning at approximately age 20 years, and dementia beginning at approximately age 40 years. Psychiatric symptoms such as personality change and paranoia may appear in childhood and progress. The hearing impairment appears to be consistent in age of onset and progression, whereas the neurologic, visual, and neuropsychiatric signs vary in degree of severity and rate of progression. Females may have mild hearing impairment and focal dystonia.
Aicardi Goutieres syndrome 1
MedGen UID:
162912
Concept ID:
C0796126
Disease or Syndrome
Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known.
Wieacker-Wolff syndrome
MedGen UID:
163227
Concept ID:
C0796200
Disease or Syndrome
Wieacker-Wolff syndrome (WRWF) is a severe X-linked recessive neurodevelopmental disorder affecting the central and peripheral nervous systems. It is characterized by onset of muscle weakness in utero (fetal akinesia), which results in arthrogryposis multiplex congenita (AMC) apparent at birth. Affected boys are born with severe contractures, show delayed motor development, facial and bulbar weakness, characteristic dysmorphic facial features, and skeletal abnormalities, such as hip dislocation, scoliosis, and foot deformities. Additional features include global developmental delay with poor or absent speech and impaired intellectual development, feeding difficulties and poor growth, hypotonia, hypogenitalism, and spasticity. Carrier females may be unaffected or have mild features of the disorder (summary by Hirata et al., 2013 and Frints et al., 2019).
BH4-deficient hyperphenylalaninemia A
MedGen UID:
209234
Concept ID:
C0878676
Disease or Syndrome
Tetrahydrobiopterin (BH4)-deficient hyperphenylalaninemia (HPA) comprises a genetically heterogeneous group of progressive neurologic disorders caused by autosomal recessive mutations in the genes encoding enzymes involved in the synthesis or regeneration of BH4. BH4 is a cofactor for phenylalanine hydroxylase (PAH; 612349), tyrosine hydroxylase (TH; 191290) and tryptophan hydroxylase (TPH1; 191060), the latter 2 of which are involved in neurotransmitter synthesis. The BH4-deficient HPAs are characterized phenotypically by hyperphenylalaninemia, depletion of the neurotransmitters dopamine and serotonin, and progressive cognitive and motor deficits (Dudesek et al., 2001). HPABH4A, caused by mutations in the PTS gene, represents the most common cause of BH4-deficient hyperphenylalaninemia (Dudesek et al., 2001). Other forms of BH4-deficient HPA include HPABH4B (233910), caused by mutation in the GCH1 gene (600225), HPABH4C (261630), caused by mutation in the QDPR gene (612676), and HPABH4D (264070), caused by mutation in the PCBD1 gene (126090). Niederwieser et al. (1982) noted that about 1 to 3% of patients with hyperphenylalaninemia have one of these BH4-deficient forms. These disorders are clinically and genetically distinct from classic phenylketonuria (PKU; 261600), caused by mutation in the PAH gene. Two additional disorders associated with BH4 deficiency and neurologic symptoms do not have overt hyperphenylalaninemia as a feature: dopa-responsive dystonia (612716), caused by mutation in the SPR gene (182125), and autosomal dominant dopa-responsive dystonia (DYT5; 128230), caused by mutation in the GCH1 gene. Patients with these disorders may develop hyperphenylalaninemia when stressed.
Leber hereditary optic neuropathy
MedGen UID:
182973
Concept ID:
C0917796
Disease or Syndrome
Leber hereditary optic neuropathy (LHON) typically presents in young adults as bilateral, painless, subacute visual failure. The peak age of onset in LHON is in the second and third decades of life, with 90% of those who lose their vision doing so before age 50 years. Very rarely, individuals first manifest LHON in the seventh and eighth decades of life. Males are four to five times more likely to be affected than females, but neither gender nor mutational status significantly influences the timing and severity of the initial visual loss. Neurologic abnormalities such as postural tremor, peripheral neuropathy, nonspecific myopathy, and movement disorders have been reported to be more common in individuals with LHON than in the general population. Some individuals with LHON, usually women, may also develop a multiple sclerosis-like illness.
Deficiency of beta-ureidopropionase
MedGen UID:
226944
Concept ID:
C1291512
Disease or Syndrome
Beta-ureidopropionase deficiency is a rare autosomal recessive inborn error of metabolism due to a defect in pyrimidine degradation. Less than 10 patients have been reported, and the phenotype can range from severe neurologic involvement with mental retardation and seizures to normal neurologic development (Yaplito-Lee et al., 2008).
Episodic ataxia type 2
MedGen UID:
314039
Concept ID:
C1720416
Disease or Syndrome
The hereditary ataxias are a group of genetic disorders characterized by slowly progressive incoordination of gait and often associated with poor coordination of hands, speech, and eye movements. Frequently, atrophy of the cerebellum occurs. In this GeneReview the hereditary ataxias are categorized by mode of inheritance and gene (or chromosome locus) in which pathogenic variants occur.
Cerebellar ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss syndrome
MedGen UID:
318633
Concept ID:
C1832466
Disease or Syndrome
ATP1A3-related neurologic disorders represent a clinical continuum in which at least three distinct phenotypes have been delineated: rapid-onset dystonia-parkinsonism (RDP); alternating hemiplegia of childhood (ACH); and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS). However, some affected individuals have intermediate phenotypes or only a few features that do not fit well into one of these major phenotypes. RDP has been characterized by: abrupt onset of dystonia over days to weeks with parkinsonism (primarily bradykinesia and postural instability); common bulbar involvement; and absence or minimal response to an adequate trial of L-dopa therapy, with few exceptions. Often fever, physiologic stress, or alcoholic binges trigger the onset of symptoms. After their initial appearance, symptoms often stabilize with little improvement; occasionally second episodes occur with abrupt worsening of symptoms. Rarely, affected individuals have reported a more gradual onset of symptoms over weeks to months. Anxiety, depression, and seizures have been reported. Age of onset ranges from four to 55 years, although a childhood variation of RDP with onset between ages nine and 14 months has been reported. AHC is a complex neurodevelopmental syndrome most frequently manifesting in infancy or early childhood with paroxysmal episodic neurologic dysfunction including alternating hemiparesis or dystonia, quadriparesis, seizure-like episodes, and oculomotor abnormalities. Episodes can last for minutes, hours, days, or even weeks. Remission of symptoms occurs with sleep and immediately after awakening. Over time, persistent neurologic deficits including oculomotor apraxia, ataxia, choreoathetosis, dystonia, parkinsonism, and cognitive and behavioral dysfunction develop in the majority of those affected; more than 50% develop epilepsy in addition to their episodic movement disorder phenotype. CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) syndrome is characterized by episodes of ataxic encephalopathy and/or weakness during and after a febrile illness. Onset is between ages six months and four years. Some acute symptoms resolve; progression of sensory losses and severity vary.
Dystonia 9
MedGen UID:
371427
Concept ID:
C1832855
Disease or Syndrome
The phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS) is now known to be a continuum that includes the classic phenotype as well as paroxysmal exercise-induced dyskinesia and epilepsy (previously known as dystonia 18 [DYT18]) and paroxysmal choreoathetosis with spasticity (previously known as dystonia 9 [DYT9]), atypical childhood absence epilepsy, myoclonic astatic epilepsy, and paroxysmal non-epileptic findings including intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The classic phenotype is characterized by infantile-onset seizures, delayed neurologic development, acquired microcephaly, and complex movement disorders. Seizures in classic early-onset Glut1 DS begin before age six months. Several seizure types occur: generalized tonic or clonic, focal, myoclonic, atypical absence, atonic, and unclassified. In some infants, apneic episodes and abnormal episodic eye-head movements similar to opsoclonus may precede the onset of seizures. The frequency, severity, and type of seizures vary among affected individuals and are not related to disease severity. Cognitive impairment, ranging from learning disabilities to severe intellectual disability, is typical. The complex movement disorder, characterized by ataxia, dystonia, and chorea, may occur in any combination and may be continuous, paroxysmal, or continual with fluctuations in severity influenced by environmental factors such as fasting or with infectious stress. Symptoms often improve substantially when a ketogenic diet is started.
Amyotrophic lateral sclerosis 17
MedGen UID:
318833
Concept ID:
C1833296
Disease or Syndrome
CHMP2B frontotemporal dementia (CHMP2B-FTD) has been described in a single family from Denmark, in one individual with familial FTD from Belgium, and in one individual with FTD and no family history. It typically starts between ages 46 and 65 years with subtle personality changes and slowly progressive behavioral changes, dysexecutive syndrome, dyscalculia, and language disturbances. Disinhibition or loss of initiative is the most common presenting symptom. The disease progresses over a few years into profound dementia with extrapyramidal symptoms and mutism. Several individuals have developed an asymmetric akinetic rigid syndrome with arm and gait dystonia and pyramidal signs that may be related to treatment with neuroleptic drugs. Symptoms and disease course are highly variable. Disease duration may be as short as three years or longer than 20 years.
Epilepsy, nocturnal frontal lobe, type 4
MedGen UID:
332082
Concept ID:
C1835905
Disease or Syndrome
Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is characterized by clusters of nocturnal motor seizures, which are often stereotyped and brief (5 seconds to 5 minutes). They vary from simple arousals from sleep to dramatic, often bizarre hyperkinetic events with tonic or dystonic features. Affected individuals may experience aura. Retained awareness during seizures is common. A minority of individuals experience daytime seizures. Onset ranges from infancy to adulthood. About 80% of individuals develop ADNFLE in the first two decades of life; mean age of onset is ten years. Clinical neurologic examination is normal and intellect is usually preserved, but reduced intellect, psychiatric comorbidity, or cognitive deficits may occur. Within a family, the manifestations of the disorder may vary considerably. ADNFLE is lifelong but not progressive. As an individual reaches middle age, attacks may become milder and less frequent.
Aicardi Goutieres syndrome 4
MedGen UID:
332084
Concept ID:
C1835912
Disease or Syndrome
Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known.
Aicardi Goutieres syndrome 3
MedGen UID:
324389
Concept ID:
C1835916
Disease or Syndrome
Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known.
Hereditary spastic paraplegia 26
MedGen UID:
373138
Concept ID:
C1836632
Disease or Syndrome
SPG26 is an autosomal recessive form of complicated spastic paraplegia characterized by onset in the first 2 decades of life of gait abnormalities due to lower limb spasticity and muscle weakness. Some patients have upper limb involvement. Additional features include intellectual disability, peripheral neuropathy, dysarthria, cerebellar signs, extrapyramidal signs, and cortical atrophy. The disorder is slowly progressive (summary by Boukhris et al., 2013). For a discussion of genetic heterogeneity of autosomal recessive SPG, see SPG5A (270800).
Leukodystrophy, hypomyelinating, 2
MedGen UID:
325157
Concept ID:
C1837355
Disease or Syndrome
Pelizaeus-Merzbacher-like disease 1 (PMLD1) is a slowly progressive leukodystrophy that typically presents during the neonatal or early-infantile period with nystagmus, commonly associated with hypotonia, delayed acquisition of motor milestones, speech delay, and dysarthria. Over time the hypotonia typically evolves into spasticity that affects the ability to walk and communicate. Cerebellar signs (gait ataxia, dysmetria, intention tremor, head titubation, and dysdiadochokinesia) frequently manifest during childhood. Some individuals develop extrapyramidal movement abnormalities (choreoathetosis and dystonia). Hearing loss and optic atrophy are observed in rare cases. Motor impairments can lead to swallowing difficulty and orthopedic complications, including hip dislocation and scoliosis. Most individuals have normal cognitive skills or mild intellectual disability – which, however, can be difficult to evaluate in the context of profound motor impairment.
Leber optic atrophy and dystonia
MedGen UID:
333240
Concept ID:
C1839040
Disease or Syndrome
Pyruvate dehydrogenase E1-alpha deficiency
MedGen UID:
326486
Concept ID:
C1839413
Disease or Syndrome
Genetic defects in the pyruvate dehydrogenase complex are one of the most common causes of primary lactic acidosis in children. Most cases are caused by mutation in the E1-alpha subunit gene on the X chromosome. X-linked PDH deficiency is one of the few X-linked diseases in which a high proportion of heterozygous females manifest severe symptoms. The clinical spectrum of PDH deficiency is broad, ranging from fatal lactic acidosis in the newborn to chronic neurologic dysfunction with structural abnormalities in the central nervous system without systemic acidosis (Robinson et al., 1987; Brown et al., 1994). Genetic Heterogeneity of Pyruvate Dehydrogenase Complex Deficiency PDH deficiency can also be caused by mutation in other subunits of the PDH complex, including a form (PDHXD; 245349) caused by mutation in the component X gene (PDHX; 608769) on chromosome 11p13; a form (PDHBD; 614111) caused by mutation in the PDHB gene (179060) on chromosome 3p14; a form (PDHDD; 245348) caused by mutation in the DLAT gene (608770) on chromosome 11q23; a form (PDHPD; 608782) caused by mutation in the PDP1 gene (605993) on chromosome 8q22; and a form (PDHLD; 614462) caused by mutation in the LIAS gene (607031) on chromosome 4p14.
GLUT1 deficiency syndrome 2
MedGen UID:
330866
Concept ID:
C1842534
Disease or Syndrome
The phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS) is now known to be a continuum that includes the classic phenotype as well as paroxysmal exercise-induced dyskinesia and epilepsy (previously known as dystonia 18 [DYT18]) and paroxysmal choreoathetosis with spasticity (previously known as dystonia 9 [DYT9]), atypical childhood absence epilepsy, myoclonic astatic epilepsy, and paroxysmal non-epileptic findings including intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The classic phenotype is characterized by infantile-onset seizures, delayed neurologic development, acquired microcephaly, and complex movement disorders. Seizures in classic early-onset Glut1 DS begin before age six months. Several seizure types occur: generalized tonic or clonic, focal, myoclonic, atypical absence, atonic, and unclassified. In some infants, apneic episodes and abnormal episodic eye-head movements similar to opsoclonus may precede the onset of seizures. The frequency, severity, and type of seizures vary among affected individuals and are not related to disease severity. Cognitive impairment, ranging from learning disabilities to severe intellectual disability, is typical. The complex movement disorder, characterized by ataxia, dystonia, and chorea, may occur in any combination and may be continuous, paroxysmal, or continual with fluctuations in severity influenced by environmental factors such as fasting or with infectious stress. Symptoms often improve substantially when a ketogenic diet is started.
Alzheimer disease, type 3
MedGen UID:
334304
Concept ID:
C1843013
Disease or Syndrome
Alzheimer disease can be classified as early-onset or late-onset. The signs and symptoms of the early-onset form appear between a person's thirties and mid-sixties, while the late-onset form appears during or after a person's mid-sixties. The early-onset form is much less common than the late-onset form, accounting for less than 10 percent of all cases of Alzheimer disease.\n\nAffected individuals usually survive 8 to 10 years after the appearance of symptoms, but the course of the disease can range from 1 to 25 years. Survival is usually shorter in individuals diagnosed after age 80 than in those diagnosed at a younger age. Death usually results from pneumonia, malnutrition, or general body wasting (inanition).\n\nAs the disorder progresses, some people with Alzheimer disease experience personality and behavioral changes and have trouble interacting in a socially appropriate manner. Other common symptoms include agitation, restlessness, withdrawal, and loss of language skills. People with this disease usually require total care during the advanced stages of the disease.\n\nMemory loss is the most common sign of Alzheimer disease. Forgetfulness may be subtle at first, but the loss of memory worsens over time until it interferes with most aspects of daily living. Even in familiar settings, a person with Alzheimer disease may get lost or become confused. Routine tasks such as preparing meals, doing laundry, and performing other household chores can be challenging. Additionally, it may become difficult to recognize people and name objects. Affected people increasingly require help with dressing, eating, and personal care.\n\nAlzheimer disease is a degenerative disease of the brain that causes dementia, which is a gradual loss of memory, judgment, and ability to function. This disorder usually appears in people older than age 65, but less common forms of the disease appear earlier in adulthood.
Niemann-Pick disease, type C2
MedGen UID:
335942
Concept ID:
C1843366
Disease or Syndrome
Niemann-Pick disease type C (NPC) is a slowly progressive lysosomal disorder whose principal manifestations are age dependent. The manifestations in the perinatal period and infancy are predominantly visceral, with hepatosplenomegaly, jaundice, and (in some instances) pulmonary infiltrates. From late infancy onward, the presentation is dominated by neurologic manifestations. The youngest children may present with hypotonia and developmental delay, with the subsequent emergence of ataxia, dysarthria, dysphagia, and, in some individuals, epileptic seizures, dystonia, and gelastic cataplexy. Although cognitive impairment may be subtle at first, it eventually becomes apparent that affected individuals have a progressive dementia. Older teenagers and young adults may present predominantly with apparent early-onset dementia or psychiatric manifestations; however, careful examination usually identifies typical neurologic signs.
Spastic paraplegia, ataxia, and mental retardation
MedGen UID:
336010
Concept ID:
C1843661
Disease or Syndrome
Myoclonic dystonia 15
MedGen UID:
334492
Concept ID:
C1843786
Disease or Syndrome
A myoclonic dystonia characterized by autosomal dominant inheritance that has material basis in variation in the chromosome region 18p11.
Biotin-responsive basal ganglia disease
MedGen UID:
375289
Concept ID:
C1843807
Disease or Syndrome
Biotin-thiamine-responsive basal ganglia disease (BTBGD) may present in childhood, early infancy, or adulthood. The classic presentation of BTBGD occurs in childhood (age 3-10 years) and is characterized by recurrent subacute encephalopathy manifest as confusion, seizures, ataxia, dystonia, supranuclear facial palsy, external ophthalmoplegia, and/or dysphagia which, if left untreated, can eventually lead to coma and even death. Dystonia and cogwheel rigidity are nearly always present; hyperreflexia, ankle clonus, and Babinski responses are common. Hemiparesis or quadriparesis may be seen. Episodes are often triggered by febrile illness or mild trauma or stress. Simple partial or generalized seizures are easily controlled with antiepileptic drugs. An early-infantile Leigh-like syndrome / atypical infantile spasms presentation occurs in the first three months of life with poor feeding, vomiting, acute encephalopathy, and severe lactic acidosis. An adult-onset Wernicke-like encephalopathy presentation is characterized by acute onset of status epilepticus, ataxia, nystagmus, diplopia, and ophthalmoplegia in the second decade of life. Prompt administration of biotin and thiamine early in the disease course results in partial or complete improvement within days in the childhood and adult presentations, but most with the infantile presentation have had poor outcome even after supplementation with biotin and thiamine.
Creatine transporter deficiency
MedGen UID:
337451
Concept ID:
C1845862
Disease or Syndrome
The cerebral creatine deficiency syndromes (CCDS), inborn errors of creatine metabolism, include the two creatine biosynthesis disorders, guanidinoacetate methyltransferase (GAMT) deficiency and L-arginine:glycine amidinotransferase (AGAT) deficiency, and the creatine transporter (CRTR) deficiency. Intellectual disability and seizures are common to all three CCDS. The majority of individuals with GAMT deficiency have a behavior disorder that can include autistic behaviors and self-mutilation; about 40% have movement disorder. Onset is between ages three months and three years. Only 14 individuals with AGAT deficiency have been reported. The phenotype of CRTR deficiency in affected males ranges from mild intellectual disability and speech delay to severe intellectual disability, seizures, movement disorder, and behavior disorder; age at diagnosis ranges from two to 66 years. Clinical phenotype of females heterozygous for CRTR deficiency ranges from asymptomatic to severe phenotype resembling male phenotype.
Autosomal recessive cerebellar ataxia-saccadic intrusion syndrome
MedGen UID:
335442
Concept ID:
C1846492
Disease or Syndrome
VPS13D movement disorder is a hyperkinetic movement disorder (dystonia, chorea, and/or ataxia) of variable age of onset that can be associated with developmental delay. Onset ranges from birth to adulthood. Individuals can present in childhood with motor delays and gait instability. Cognitive impairment ranging from mild intellectual disability to developmental delay has been reported, and several individuals have normal cognitive function. Individuals have also presented as young adults with gait difficulties caused by spastic ataxia or ataxia. In addition to gait ataxia, affected individuals had limb ataxia, dysarthria, and eye movement abnormalities (macro-saccadic oscillations, nystagmus, and saccadic pursuit). Additional features reported in some individuals include peripheral neuropathy and/or seizures. The disorder progresses to spastic ataxia or generalized dystonia, which can lead to loss of independent ambulation.
Hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration
MedGen UID:
337612
Concept ID:
C1846582
Disease or Syndrome
Pantothenate kinase-associated neurodegeneration (PKAN) is a type of neurodegeneration with brain iron accumulation (NBIA). The phenotypic spectrum of PKAN includes classic PKAN and atypical PKAN. Classic PKAN is characterized by early childhood onset of progressive dystonia, dysarthria, rigidity, and choreoathetosis. Pigmentary retinal degeneration is common. Atypical PKAN is characterized by later onset (age >10 years), prominent speech defects, psychiatric disturbances, and more gradual progression of disease.
Spinocerebellar ataxia type 17
MedGen UID:
337637
Concept ID:
C1846707
Disease or Syndrome
Spinocerebellar ataxia type 17 (SCA17) is characterized by ataxia, dementia, and involuntary movements, including chorea and dystonia. Psychiatric symptoms, pyramidal signs, and rigidity are common. The age of onset ranges from three to 55 years. Individuals with full-penetrance alleles develop neurologic and/or psychiatric symptoms by age 50 years. Ataxia and psychiatric abnormalities are frequently the initial findings, followed by involuntary movement, parkinsonism, dementia, and pyramidal signs. Brain MRI shows variable atrophy of the cerebrum, brain stem, and cerebellum. The clinical features correlate with the length of the polyglutamine expansion but are not absolutely predictive of the clinical course.
Dyskinesia, familial, with facial myokymia
MedGen UID:
338280
Concept ID:
C1847627
Disease or Syndrome
ADCY5 dyskinesia is a hyperkinetic movement disorder (more prominent in the face and arms than the legs) characterized by infantile to late-adolescent onset of chorea, athetosis, dystonia, myoclonus, or a combination of these. To date, affected individuals have had overlapping (but not identical) manifestations with wide-ranging severity. The facial movements are typically periorbital and perioral. The dyskinesia is prone to episodic or paroxysmal exacerbation lasting minutes to hours, and may occur during sleep. Precipitating factors in some persons have included emotional stress, intercurrent illness, sneezing, or caffeine; in others, no precipitating factors have been identified. In some children, severe infantile axial hypotonia results in gross motor delays accompanied by chorea, sometimes with language delays. The overall tendency is for the abnormal movements to stabilize in early middle age, at which point they may improve in some individuals; less commonly, the abnormal movements are slowly progressive, increasing in severity and frequency.
Kufor-Rakeb syndrome
MedGen UID:
338281
Concept ID:
C1847640
Disease or Syndrome
Kufor-Rakeb syndrome is a rare autosomal recessive form of juvenile-onset atypical Parkinson disease (PARK9) associated with supranuclear gaze palsy, spasticity, and dementia. Some patients have neuroradiologic evidence of iron deposition in the basal ganglia, indicating that the pathogenesis of PARK9 can be considered among the syndromes of neurodegeneration with brain iron accumulation (NBIA; see 234200) (summary by Bruggemann et al., 2010). For a phenotypic description and a discussion of genetic heterogeneity of Parkinson disease (PD), see 168600. Biallelic mutation in the ATP13A2 gene also causes autosomal recessive spastic paraplegia-78 (SPG78; 617225), an adult-onset neurodegenerative disorder with overlapping features. Patients with SPG78 have later onset and prominent spasticity, but rarely parkinsonism. Loss of ATP13A2 function results in a multidimensional spectrum of neurologic features reflecting various regions of the brain and nervous system, including cortical, pyramidal, extrapyramidal, brainstem, cerebellar, and peripheral (summary by Estrada-Cuzcano et al., 2017).
Huntington disease-like 2
MedGen UID:
341120
Concept ID:
C1847987
Disease or Syndrome
Huntington disease-like 2 (HDL2) typically presents in midlife with a relentless progressive triad of movement, emotional, and cognitive abnormalities which lead to death within ten to 20 years. HDL2 cannot be differentiated from Huntington disease clinically. Neurologic abnormalities include chorea, hypokinesia (rigidity, bradykinesia), dysarthria, and hyperreflexia in the later stages of the disease. There is a strong correlation between the duration of the disease and the progression of the motor and cognitive disorder.
Methylmalonic acidemia with homocystinuria cblD
MedGen UID:
341253
Concept ID:
C1848552
Disease or Syndrome
Disorders of intracellular cobalamin metabolism have a variable phenotype and age of onset that are influenced by the severity and location within the pathway of the defect. The prototype and best understood phenotype is cblC; it is also the most common of these disorders. The age of initial presentation of cblC spans a wide range: In utero with fetal presentation of nonimmune hydrops, cardiomyopathy, and intrauterine growth restriction. Newborns, who can have microcephaly, poor feeding, and encephalopathy. Infants, who can have poor feeding and slow growth, neurologic abnormality, and, rarely, hemolytic uremic syndrome (HUS). Toddlers, who can have poor growth, progressive microcephaly, cytopenias (including megaloblastic anemia), global developmental delay, encephalopathy, and neurologic signs such as hypotonia and seizures. Adolescents and adults, who can have neuropsychiatric symptoms, progressive cognitive decline, thromboembolic complications, and/or subacute combined degeneration of the spinal cord.
Peroxisomal acyl-CoA oxidase deficiency
MedGen UID:
376636
Concept ID:
C1849678
Disease or Syndrome
Peroxisomal acyl-CoA oxidase deficiency is a disorder of peroxisomal fatty acid beta-oxidation. See also D-bifunctional protein deficiency (261515), caused by mutation in the HSD17B4 gene (601860) on chromosome 5q2. The clinical manifestations of these 2 deficiencies are similar to those of disorders of peroxisomal assembly, including Zellweger cerebrohepatorenal syndrome (see 214100) and neonatal adrenoleukodystrophy (see 601539) (Watkins et al., 1995).
Parkinson disease 15
MedGen UID:
337969
Concept ID:
C1850100
Disease or Syndrome
A rare genetic neurological disorder with characteristics of the association of both parkinsonian (such as bradykinesia, rigidity and/or rest tremor) and pyramidal (such as increased reflexes, extensor plantar reflexes, pyramidal weakness or spasticity) manifestations, which vary according to the underlying associated disease (for example neurodegenerative disease, inborn errors of metabolism).
Navajo neurohepatopathy
MedGen UID:
338045
Concept ID:
C1850406
Disease or Syndrome
MPV17-related mitochondrial DNA (mtDNA) maintenance defect presents in the vast majority of affected individuals as an early-onset encephalohepatopathic (hepatocerebral) disease that is typically associated with mtDNA depletion, particularly in the liver. A later-onset neuromyopathic disease characterized by myopathy and neuropathy, and associated with multiple mtDNA deletions in muscle, has also rarely been described. MPV17-related mtDNA maintenance defect, encephalohepatopathic form is characterized by: Hepatic manifestations (liver dysfunction that typically progresses to liver failure, cholestasis, hepatomegaly, and steatosis); Neurologic involvement (developmental delay, hypotonia, microcephaly, and motor and sensory peripheral neuropathy); Gastrointestinal manifestations (gastrointestinal dysmotility, feeding difficulties, and failure to thrive); and Metabolic derangements (lactic acidosis and hypoglycemia). Less frequent manifestations include renal tubulopathy, nephrocalcinosis, and hypoparathyroidism. Progressive liver disease often leads to death in infancy or early childhood. Hepatocellular carcinoma has been reported.
Dystonia 5
MedGen UID:
342121
Concept ID:
C1851920
Disease or Syndrome
GTP cyclohydrolase 1-deficient dopa-responsive dystonia (GTPCH1-deficient DRD) is characterized by childhood-onset dystonia and a dramatic and sustained response to low doses of oral administration of levodopa. This disorder typically presents with gait disturbance caused by foot dystonia, later development of parkinsonism, and diurnal fluctuation of symptoms (aggravation of symptoms toward the evening and alleviation of symptoms in the morning after sleep). Initial symptoms are often gait difficulties attributable to flexion-inversion (equinovarus posture) of the foot. Occasionally, initial symptoms are arm dystonia, postural tremor of the hand, or slowness of movements. Brisk deep-tendon reflexes in the legs, ankle clonus, and/or the striatal toe (dystonic extension of the big toe) are present in many affected individuals. In general, gradual progression to generalized dystonia is observed. Intellectual, cerebellar, sensory, and autonomic disturbances generally do not occur.
Spinocerebellar ataxia type 28
MedGen UID:
339941
Concept ID:
C1853249
Disease or Syndrome
Spinocerebellar ataxia type 28 (SCA28) is characterized by young-adult onset, very slowly progressive gait and limb ataxia resulting in coordination and balance problems, dysarthria, ptosis, nystagmus, and ophthalmoparesis. In most individuals, SCA28 presents as a loss of coordination of lower limbs (unsteadiness, gait ataxia). Less frequently, ptosis/ophthalmoplegia, dysarthria, or upper-limb incoordination may occur as the initial finding. The course of the disease is slowly progressive without impairment of functional autonomy even decades after onset.
Spinocerebellar ataxia, autosomal recessive, with axonal neuropathy 2
MedGen UID:
340052
Concept ID:
C1853761
Disease or Syndrome
Ataxia with oculomotor apraxia type 2 (AOA2) is characterized by onset of ataxia between age three and 30 years after initial normal development, axonal sensorimotor neuropathy, oculomotor apraxia, cerebellar atrophy, and elevated serum concentration of alpha-fetoprotein (AFP).
Parkinson disease 6, autosomal recessive early-onset
MedGen UID:
342982
Concept ID:
C1853833
Disease or Syndrome
PINK1 type of young-onset Parkinson disease is characterized by early onset (mean age 33 years) of tremor, bradykinesia, and rigidity that are often indistinguishable from other causes of Parkinson disease. Lower-limb dystonia may be a presenting sign. Postural instability, hyperreflexia, abnormal behavior, and psychiatric manifestations have been described. The disease is usually slowly progressive. Individuals have a marked and sustained response to oral administration of levodopa (L-dopa), frequently associated with L-dopa-induced fluctuations and dyskinesias.
Mitochondrial complex II deficiency, nuclear type 1
MedGen UID:
344401
Concept ID:
C1855008
Disease or Syndrome
Mitochondrial complex II deficiency is an autosomal recessive multisystemic metabolic disorder with a highly variable phenotype. Some patients have multisystem involvement of the brain, heart, and muscle with onset in infancy, whereas others have only isolated cardiac or muscle involvement. Measurement of complex II activity in muscle is the most reliable means of diagnosis; however, there is no clear correlation between residual complex II activity and severity or clinical outcome. In some cases, treatment with riboflavin may have clinical benefit (summary by Jain-Ghai et al., 2013). Complex II, also known as succinate dehydrogenase, is part of the mitochondrial respiratory chain. Genetic Heterogeneity of Mitochondrial Complex II Deficiency See MC2DN2 (619166), caused by mutation in the SDHAF1 gene (612848) on chromosome 19q13; MC2DN3 (619167), caused by mutation in the SDHD gene (602690) on chromosome 11q23; and MC2DN4 (619224), caused by mutation in the SDHB gene (185470) on chromosome 1p36. Fullerton et al. (2020) reviewed the genetic basis of isolated mitochondrial complex II deficiency.
Mitochondrial myopathy-lactic acidosis-deafness syndrome
MedGen UID:
343245
Concept ID:
C1855033
Disease or Syndrome
Mitochondrial myopathy-lactic acidosis-deafness is a type of metabolic myopathy described only in two sisters to date, presenting during childhood, and characterized clinically by growth failure, severe muscle weakness, and moderate sensorineural deafness and biochemically by metabolic acidosis, elevated serum pyruvate concentration, hyperalaninemia and hyperalaninuria. There have been no further descriptions in the literature since 1973.
Pyruvate dehydrogenase E3-binding protein deficiency
MedGen UID:
343383
Concept ID:
C1855553
Disease or Syndrome
Pyruvate dehydrogenase deficiency is characterized by the buildup of a chemical called lactic acid in the body and a variety of neurological problems. Signs and symptoms of this condition usually first appear shortly after birth, and they can vary widely among affected individuals. The most common feature is a potentially life-threatening buildup of lactic acid (lactic acidosis), which can cause nausea, vomiting, severe breathing problems, and an abnormal heartbeat. People with pyruvate dehydrogenase deficiency usually have neurological problems as well. Most have delayed development of mental abilities and motor skills such as sitting and walking. Other neurological problems can include intellectual disability, seizures, weak muscle tone (hypotonia), poor coordination, and difficulty walking. Some affected individuals have abnormal brain structures, such as underdevelopment of the tissue connecting the left and right halves of the brain (corpus callosum), wasting away (atrophy) of the exterior part of the brain known as the cerebral cortex, or patches of damaged tissue (lesions) on some parts of the brain. Because of the severe health effects, many individuals with pyruvate dehydrogenase deficiency do not survive past childhood, although some may live into adolescence or adulthood.
Dystonia with ringbinden
MedGen UID:
346509
Concept ID:
C1857089
Disease or Syndrome
2,4-Dienoyl-CoA reductase deficiency
MedGen UID:
346552
Concept ID:
C1857252
Disease or Syndrome
2,4-Dienoyl-CoA reductase deficiency (DECRD) is a rare autosomal recessive inborn error of metabolism resulting in mitochondrial dysfunction due to impaired production of NADPH, which is an essential cofactor for several mitochondrial enzymes. Affected individuals have a variable phenotype: some may have severe neurologic symptoms and metabolic dysfunction beginning in early infancy, whereas others may present with more subtle features, such as childhood-onset optic atrophy or intermittent muscle weakness. The variable severity is putatively dependent on the effect of the mutation on the NADK2 enzyme. Biochemical analysis typically shows hyperlysinemia, due to defective activity of the mitochondrial NADP(H)-dependent enzyme AASS (605113), which is usually a benign finding. More severe cases have increased C10:2-carnitine levels, due to defective activity of the enzyme DECR (DECR1; 222745) (summary by Houten et al., 2014 and Pomerantz et al., 2018).
Neurodegeneration with brain iron accumulation 2b
MedGen UID:
346658
Concept ID:
C1857747
Disease or Syndrome
PLA2G6-associated neurodegeneration (PLAN) comprises a continuum of three phenotypes with overlapping clinical and radiologic features: Infantile neuroaxonal dystrophy (INAD). Atypical neuroaxonal dystrophy (atypical NAD). PLA2G6-related dystonia-parkinsonism. INAD usually begins between ages six months and three years with psychomotor regression or delay, hypotonia, and progressive spastic tetraparesis. Many affected children never learn to walk or lose the ability shortly after attaining it. Strabismus, nystagmus, and optic atrophy are common. Disease progression is rapid, resulting in severe spasticity, progressive cognitive decline, and visual impairment. Many affected children do not survive beyond their first decade. Atypical NAD shows more phenotypic variability than INAD. In general, onset is in early childhood but can be as late as the end of the second decade. The presenting signs may be gait instability, ataxia, or speech delay and autistic features, which are sometimes the only evidence of disease for a year or more. Strabismus, nystagmus, and optic atrophy are common. Neuropsychiatric disturbances including impulsivity, poor attention span, hyperactivity, and emotional lability are also common. The course is fairly stable during early childhood and resembles static encephalopathy but is followed by neurologic deterioration between ages seven and 12 years. PLA2G6-related dystonia-parkinsonism has a variable age of onset, but most individuals present in early adulthood with gait disturbance or neuropsychiatric changes. Affected individuals consistently develop dystonia and parkinsonism (which may be accompanied by rapid cognitive decline) in their late teens to early twenties. Dystonia is most common in the hands and feet but may be more generalized. The most common features of parkinsonism in these individuals are bradykinesia, resting tremor, rigidity, and postural instability.
Huntington disease-like 3
MedGen UID:
347622
Concept ID:
C1858114
Disease or Syndrome
A rare Huntington disease-like syndrome with characteristics of childhood-onset progressive neurologic deterioration with pyramidal and extrapyramidal abnormalities, chorea, dystonia, ataxia, gait instability, spasticity, seizures, mutism, and (on brain MRI) progressive frontal cortical atrophy and bilateral caudate atrophy.
Ataxia-oculomotor apraxia type 1
MedGen UID:
395301
Concept ID:
C1859598
Disease or Syndrome
Ataxia with oculomotor apraxia type 1 (AOA1) is characterized by childhood onset of slowly progressive cerebellar ataxia, followed by oculomotor apraxia and a severe primary motor peripheral axonal motor neuropathy. The first manifestation is progressive gait imbalance (mean age of onset: 4.3 years; range: 2-10 years), followed by dysarthria, then upper-limb dysmetria with mild intention tremor. Oculomotor apraxia, usually noticed a few years after the onset of ataxia, progresses to external ophthalmoplegia. All affected individuals have generalized areflexia followed by a peripheral neuropathy and quadriplegia with loss of ambulation about seven to ten years after onset. Hands and feet are short and atrophic. Chorea and upper-limb dystonia are common. Intellect remains normal in some individuals; in others, different degrees of cognitive impairment have been observed.
Ataxia-telangiectasia with generalized skin pigmentation and early death
MedGen UID:
395306
Concept ID:
C1859615
Disease or Syndrome
Amyotrophic lateral sclerosis type 2, juvenile
MedGen UID:
349246
Concept ID:
C1859807
Disease or Syndrome
ALS2-related disorder involves retrograde degeneration of the upper motor neurons of the pyramidal tracts and comprises a clinical continuum of the following three phenotypes: Infantile ascending hereditary spastic paraplegia (IAHSP), characterized by onset of spasticity with increased reflexes and sustained clonus of the lower limbs within the first two years of life, progressive weakness and spasticity of the upper limbs by age seven to eight years, and wheelchair dependence in the second decade with progression toward severe spastic tetraparesis and a pseudobulbar syndrome caused by progressive cranial nerve involvement. Juvenile primary lateral sclerosis (JPLS), characterized by upper motor neuron findings of pseudobulbar palsy and spastic quadriplegia without dementia or cerebellar, extrapyramidal, or sensory signs. Juvenile amyotrophic lateral sclerosis (JALS or ALS2), characterized by onset between ages three and 20 years. All affected individuals show a spastic pseudobulbar syndrome (spasticity of speech and swallowing) together with spastic paraplegia. Some individuals are bedridden by age 12 to 50 years.
Triosephosphate isomerase deficiency
MedGen UID:
349893
Concept ID:
C1860808
Disease or Syndrome
Triosephosphate isomerase deficiency (TPID) is an autosomal recessive multisystem disorder characterized by congenital hemolytic anemia, and progressive neuromuscular dysfunction beginning in early childhood. Many patients die from respiratory failure in childhood. The neurologic syndrome is variable, but usually includes lower motor neuron dysfunction with hypotonia, muscle weakness and atrophy, and hyporeflexia. Some patients may show additional signs such as dystonic posturing and/or spasticity. Laboratory studies show intracellular accumulation of dihydroxyacetone phosphate (DHAP), particularly in red blood cells (summary by Fermo et al., 2010).
Amyotrophic dystonic paraplegia
MedGen UID:
354871
Concept ID:
C1862956
Disease or Syndrome
Combined oxidative phosphorylation deficiency 3
MedGen UID:
355842
Concept ID:
C1864840
Disease or Syndrome
Combined oxidative phosphorylation deficiency type 3 is an extremely rare clinically heterogenous disorder described in about 5 patients to date. Clinical signs included hypotonia, lactic acidosis, and hepatic insufficiency, with progressive encephalomyopathy or hypertrophic cardiomyopathy.
Parkinson disease 1
MedGen UID:
357008
Concept ID:
C1868595
Disease or Syndrome
Parkinson disease is the second most common neurogenic disorder after Alzheimer disease (AD; 104300), affecting approximately 1% of the population over age 50. Clinical manifestations include resting tremor, muscular rigidity, bradykinesia, and postural instability. Additional features are characteristic postural abnormalities, dysautonomia, dystonic cramps, and dementia (Polymeropoulos et al., 1996). For a general phenotypic description and a discussion of genetic heterogeneity of Parkinson disease, see 168600.
Parkinson disease 2
MedGen UID:
401500
Concept ID:
C1868675
Disease or Syndrome
Parkin type of early-onset Parkinson disease (PARK-Parkin) is characterized by the cardinal signs of Parkinson disease (PD): bradykinesia, resting tremor, and rigidity. The median age at onset is 31 years (range: 3-81 years). The disease is slowly progressive: disease duration of more than 50 years has been reported. Clinical findings vary; hyperreflexia is common. Lower-limb dystonia may be a presenting sign and cognitive decline appears to be no more frequent than in the general population. Dyskinesia as a result of treatment with levodopa frequently occurs.
Dystonia 12
MedGen UID:
358384
Concept ID:
C1868681
Disease or Syndrome
ATP1A3-related neurologic disorders represent a clinical continuum in which at least three distinct phenotypes have been delineated: rapid-onset dystonia-parkinsonism (RDP); alternating hemiplegia of childhood (ACH); and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS). However, some affected individuals have intermediate phenotypes or only a few features that do not fit well into one of these major phenotypes. RDP has been characterized by: abrupt onset of dystonia over days to weeks with parkinsonism (primarily bradykinesia and postural instability); common bulbar involvement; and absence or minimal response to an adequate trial of L-dopa therapy, with few exceptions. Often fever, physiologic stress, or alcoholic binges trigger the onset of symptoms. After their initial appearance, symptoms often stabilize with little improvement; occasionally second episodes occur with abrupt worsening of symptoms. Rarely, affected individuals have reported a more gradual onset of symptoms over weeks to months. Anxiety, depression, and seizures have been reported. Age of onset ranges from four to 55 years, although a childhood variation of RDP with onset between ages nine and 14 months has been reported. AHC is a complex neurodevelopmental syndrome most frequently manifesting in infancy or early childhood with paroxysmal episodic neurologic dysfunction including alternating hemiparesis or dystonia, quadriparesis, seizure-like episodes, and oculomotor abnormalities. Episodes can last for minutes, hours, days, or even weeks. Remission of symptoms occurs with sleep and immediately after awakening. Over time, persistent neurologic deficits including oculomotor apraxia, ataxia, choreoathetosis, dystonia, parkinsonism, and cognitive and behavioral dysfunction develop in the majority of those affected; more than 50% develop epilepsy in addition to their episodic movement disorder phenotype. CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) syndrome is characterized by episodes of ataxic encephalopathy and/or weakness during and after a febrile illness. Onset is between ages six months and four years. Some acute symptoms resolve; progression of sensory losses and severity vary.
Ataxia, spastic, 3, autosomal recessive
MedGen UID:
370715
Concept ID:
C1969645
Disease or Syndrome
A rare genetic autosomal recessive spastic ataxia disease with characteristics of cerebellar ataxia, spasticity, cerebellar (and in some cases cerebral) atrophy, dystonia and leucoencephalopathy. Caused by homozygous or compound heterozygous complex genomic rearrangements involving the MARS2 gene on chromosome 2q33.
Ataxia, spastic, 1, autosomal dominant
MedGen UID:
409988
Concept ID:
C1970107
Disease or Syndrome
The hereditary ataxias are a group of genetic disorders characterized by slowly progressive incoordination of gait and often associated with poor coordination of hands, speech, and eye movements. Frequently, atrophy of the cerebellum occurs. In this GeneReview the hereditary ataxias are categorized by mode of inheritance and gene (or chromosome locus) in which pathogenic variants occur.
Mental retardation, autosomal recessive 6
MedGen UID:
370848
Concept ID:
C1970198
Disease or Syndrome
Episodic kinesigenic dyskinesia 2
MedGen UID:
410022
Concept ID:
C1970238
Disease or Syndrome
Choreoathetosis, hypothyroidism, and neonatal respiratory distress
MedGen UID:
369694
Concept ID:
C1970269
Disease or Syndrome
NKX2-1-related disorders range from benign hereditary chorea (BHC) to choreoathetosis, congenital hypothyroidism, and neonatal respiratory distress (also known as brain-lung-thyroid syndrome). Childhood-onset chorea, the hallmark of NKX2-1-related disorders, may or may not be associated with respiratory distress syndrome or congenital hypothyroidism. Chorea generally begins in early infancy or about age one year (most commonly) or in late childhood or adolescence, and progresses into the second decade after which it remains static or (rarely) remits. Pulmonary disease, the second most common manifestation, can include respiratory distress syndrome in neonates, interstitial lung disease in young children, and pulmonary fibrosis in older persons. The risk for pulmonary carcinoma is increased in young adults with an NKX2-1-related disorder. Thyroid dysfunction, the result of dysembryogenesis, can present as congenital hypothyroidism or compensated hypothyroidism. The risk for thyroid cancer is unknown and may not be increased. In one review, 50% of affected individuals had the full brain-lung-thyroid syndrome, 30% had involvement of brain and thyroid only, and 13% had isolated chorea only.
Dystonia with cerebellar atrophy
MedGen UID:
392987
Concept ID:
C2673697
Disease or Syndrome
Hypomyelinating leukodystrophy 7
MedGen UID:
390993
Concept ID:
C2676243
Disease or Syndrome
POLR3-related leukodystrophy, a hypomyelinating leukodystrophy with specific features on brain MRI, is characterized by varying combinations of four major clinical findings: Neurologic dysfunction, typically predominated by motor dysfunction (progressive cerebellar dysfunction, and to a lesser extent extrapyramidal [i.e., dystonia], pyramidal [i.e., spasticity] and cognitive dysfunctions). Abnormal dentition (delayed dentition, hypodontia, oligodontia, and abnormally placed or shaped teeth). Endocrine abnormalities such as short stature (in ~50% of individuals) with or without growth hormone deficiency, and more commonly, hypogonadotropic hypogonadism manifesting as delayed, arrested, or absent puberty. Ocular abnormality in the form of myopia, typically progressing over several years and becoming severe. POLR3-related leukodystrophy and 4H leukodystrophy are the two recognized terms for five previously described overlapping clinical phenotypes (initially described as distinct entities before their molecular basis was known). These include: Hypomyelination, hypodontia, hypogonadotropic hypogonadism (4H syndrome); Ataxia, delayed dentition, and hypomyelination (ADDH); Tremor-ataxia with central hypomyelination (TACH); Leukodystrophy with oligodontia (LO); Hypomyelination with cerebellar atrophy and hypoplasia of the corpus callosum (HCAHC). Age of onset is typically in early childhood but later-onset cases have also been reported. An infant with Wiedemann-Rautenstrauch syndrome (neonatal progeroid syndrome) was recently reported to have pathogenic variants in POLR3A on exome sequencing. Confirmation of this as a very severe form of POLR3-related leukodystrophy awaits replication in other individuals with a clinical diagnosis of Wiedemann-Rautenstrauch syndrome.
Leukodystrophy, hypomyelinating, 6
MedGen UID:
436642
Concept ID:
C2676244
Disease or Syndrome
TUBB4A-related leukodystrophy comprises a phenotypic spectrum in which the MRI findings range from hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) at the severe end to isolated hypomyelination at the mild end. Progressive neurologic findings reflect involvement of the pyramidal tracts (spasticity, brisk deep tendon reflexes, and Babinski sign), extrapyramidal system (rigidity, dystonia, choreoathetosis, oculogyric crisis, and perioral dyskinesia), cerebellum (ataxia, intention tremor, dysmetria), and bulbar function (dysarthria, dysphonia, and swallowing). Cognition is variably affected, usually less severely than motor function. Typically, those with H-ABC present in early childhood (ages one to three years) and those with isolated hypomyelination in later childhood or adulthood. The rate of progression varies with disease severity.
Pontocerebellar hypoplasia type 2C
MedGen UID:
382856
Concept ID:
C2676465
Disease or Syndrome
TSEN54 pontocerebellar hypoplasia (TSEN54-PCH) comprises three PCH phenotypes (PCH2, 4, and 5) that share characteristic neuroradiologic and neurologic findings. The three PCH phenotypes (which differ mainly in life expectancy) were considered to be distinct entities before their molecular basis was known. PCH2. Children usually succumb before age ten years (those with PCH4 and 5 usually succumb as neonates). Children with PCH2 have generalized clonus, uncoordinated sucking and swallowing, impaired cognitive development, lack of voluntary motor development, cortical blindness, and an increased risk for rhabdomyolysis during severe infections. Epilepsy is present in approximately 50%. PCH4. Neonates often have seizures, multiple joint contractures ("arthrogryposis"), generalized clonus, and central respiratory impairment. PCH5 resembles PCH4 and has been described in one family.
Pontocerebellar hypoplasia type 2B
MedGen UID:
393505
Concept ID:
C2676466
Disease or Syndrome
TSEN54 pontocerebellar hypoplasia (TSEN54-PCH) comprises three PCH phenotypes (PCH2, 4, and 5) that share characteristic neuroradiologic and neurologic findings. The three PCH phenotypes (which differ mainly in life expectancy) were considered to be distinct entities before their molecular basis was known. PCH2. Children usually succumb before age ten years (those with PCH4 and 5 usually succumb as neonates). Children with PCH2 have generalized clonus, uncoordinated sucking and swallowing, impaired cognitive development, lack of voluntary motor development, cortical blindness, and an increased risk for rhabdomyolysis during severe infections. Epilepsy is present in approximately 50%. PCH4. Neonates often have seizures, multiple joint contractures ("arthrogryposis"), generalized clonus, and central respiratory impairment. PCH5 resembles PCH4 and has been described in one family.
Mitochondrial DNA depletion syndrome 5 (encephalomyopathic with or without methylmalonic aciduria)
MedGen UID:
413170
Concept ID:
C2749864
Disease or Syndrome
SUCLA2-related mitochondrial DNA (mtDNA) depletion syndrome, encephalomyopathic form with methylmalonic aciduria is characterized by onset of the following features in infancy or childhood (median age of onset 2 months; range of onset birth to 6 years): psychomotor retardation, hypotonia, dystonia, muscular atrophy, sensorineural hearing impairment, postnatal growth retardation, and feeding difficulties. Other, less frequent, features include distinctive facial features, contractures, kyphoscoliosis, gastroesophageal reflux, ptosis, choreoathetosis, ophthalmoplegia, and epilepsy (infantile spasms or generalized convulsions). The median survival is 20 years; approximately 30% of affected individuals succumb during childhood. Affected individuals may have hyperintensities in the basal ganglia, cerebral atrophy, and leukoencephalopathy on head MRI. Elevation of methylmalonic acid (MMA) in the urine and plasma is found in a vast majority of affected individuals, although at levels that are far below those typically seen in individuals with classic methylmalonic aciduria.
Hypermanganesemia with dystonia, polycythemia, and cirrhosis
MedGen UID:
412958
Concept ID:
C2750442
Disease or Syndrome
The disorder dystonia/parkinsonism, hypermanganesemia, polycythemia, and chronic liver disease is characterized by the following: A movement disorder resulting from manganese accumulation in the basal ganglia. Whole-blood manganese concentrations that often exceed 2000 nmol/L (normal: <320 nmol/L). Polycythemia. Hepatomegaly with variable hepatic fibrosis/cirrhosis. Neurologic findings can manifest: in childhood (ages 2-15 years) as four-limb dystonia, leading to a characteristic high-stepping gait ("cock-walk gait"), dysarthria, fine tremor, and bradykinesia or on occasion spastic paraplegia; or in adulthood as parkinsonism (shuffling gait, rigidity, bradykinesia, hypomimia, and monotone speech) unresponsive to L-dopa treatment. Hepatic failure, secondary complications of cirrhosis, and the neurologic disorder shorten life expectancy.
Parkinson disease 14
MedGen UID:
414488
Concept ID:
C2751842
Disease or Syndrome
A rare neurodegenerative disease usually presenting before the age of 30 with characteristics of dystonia, L-dopa-responsive parkinsonism, pyramidal signs and rapid cognitive decline. Prevalence is unknown. Only 14 cases have been reported to date. Caused by mutations in the phospholipase A2, group VI (PLA2G6) gene located on chromosome 22q13.1. Inherited in an autosomal recessive manner.
Leukoencephalopathy, cystic, without megalencephaly
MedGen UID:
416646
Concept ID:
C2751843
Disease or Syndrome
RNAse T2-deficient leukoencephalopathy is a disorder that affects the brain. People with RNAse T2-deficient leukoencephalopathy have neurological problems that become apparent during infancy; the problems generally do not worsen over time (progress). Most affected individuals have severe intellectual disability; muscle stiffness (spasticity); and a delay in developing motor skills such as sitting, crawling, and walking. Some do not learn to walk, and most do not develop the ability to speak. Other neurological features that can occur in RNAse T2-deficient leukoencephalopathy include hearing loss caused by abnormalities in the inner ear (sensorineural deafness), seizures, involuntary writhing movements of the hands (athetosis), uncontrolled muscle tensing (dystonia), and involuntary eye movements (nystagmus). In addition to the neurological problems associated with this disorder, some affected individuals have unusual facial features sometimes described as a "doll-like face."\n\nThe neurological problems in this disorder are caused by abnormalities in the brain. People with this condition have leukoencephalopathy, an abnormality of the brain's white matter that can be detected with medical imaging. White matter consists of nerve fibers covered by a fatty substance called myelin. Myelin insulates nerve fibers and promotes the rapid transmission of nerve impulses. In people with RNAse T2-deficient leukoencephalopathy, myelin is not made in sufficient amounts during development, leading to patchy white matter abnormalities (lesions) in the brain. In addition, individuals with RNAse T2-deficient leukoencephalopathy may have cysts in regions of the brain called the temporal lobes and enlargement of the fluid-filled cavities (ventricles) near the center of the brain. The white matter lesions are primarily concentrated around the cysts and the ventricles. An abnormally small head and brain size (microcephaly) often occurs in this disorder.
Rett syndrome, congenital variant
MedGen UID:
462055
Concept ID:
C3150705
Disease or Syndrome
The congenital variant of Rett syndrome is a severe neurodevelopmental disorder with features of classic Rett syndrome (RTT; 312750), but earlier onset in the first months of life. Classic Rett syndrome shows later onset and is caused by mutation in the MECP2 gene (300005).
Early infantile epileptic encephalopathy 7
MedGen UID:
462336
Concept ID:
C3150986
Disease or Syndrome
KCNQ2-related disorders represent a continuum of overlapping neonatal epileptic phenotypes caused by a heterozygous pathogenic variant in KCNQ2. The clinical features of KCNQ2-related disorders range from KCNQ2-related benign familial neonatal epilepsy (KCNQ2-BFNE) at the mild end to KCNQ2-related neonatal epileptic encephalopathy (KCNQ2-NEE) at the severe end. KCNQ2-BFNE is characterized by a wide spectrum of seizure types (tonic or apneic episodes, focal clonic activity, or autonomic changes) that start in otherwise healthy infants between the second and eighth day of life and spontaneously disappear between the first and the sixth to 12th month of life. Motor activity may be confined to one body part, migrate to other body regions, or generalize. Seizures are generally brief, lasting one to two minutes. Rarely, KCNQ2-BFNE may evolve into status epilepticus. About 10%-15% of individuals with BFNE develop epileptic seizures later in life. KCNQ2-NEE is characterized by multiple daily seizures beginning in the first week of life that are mostly tonic, with associated focal motor and autonomic features. Seizures generally cease between ages nine months and four years. At onset, EEG shows a burst-suppression pattern or multifocal epileptiform activity; early brain MRI can show basal ganglia and thalamic hyperintensities that later resolve. Moderate to severe developmental impairment is present.
Mental retardation, autosomal dominant 6
MedGen UID:
462761
Concept ID:
C3151411
Mental or Behavioral Dysfunction
GRIN2B-related neurodevelopmental disorder is characterized by mild to profound developmental delay / intellectual disability (DD/ID) in all affected individuals. Muscle tone abnormalities (spasticity and/or hypotonia, occasionally associated with feeding difficulties), as well as epilepsy and autism spectrum disorder (ASD) / behavioral issues, are common. Other infantile- or childhood-onset findings include microcephaly; dystonic, dyskinetic, or choreiform movement disorder; and/or cortical visual impairment. Brain MRI reveals a malformation of cortical development in a minority of affected individuals. To date, fewer than 100 individuals with GRIN2B-related neurodevelopmental disorder have been reported.
Parkinson disease, late-onset
MedGen UID:
463618
Concept ID:
C3160718
Disease or Syndrome
Niemann-Pick disease type C1
MedGen UID:
465922
Concept ID:
C3179455
Disease or Syndrome
Niemann-Pick disease type C (NPC) is a slowly progressive lysosomal disorder whose principal manifestations are age dependent. The manifestations in the perinatal period and infancy are predominantly visceral, with hepatosplenomegaly, jaundice, and (in some instances) pulmonary infiltrates. From late infancy onward, the presentation is dominated by neurologic manifestations. The youngest children may present with hypotonia and developmental delay, with the subsequent emergence of ataxia, dysarthria, dysphagia, and, in some individuals, epileptic seizures, dystonia, and gelastic cataplexy. Although cognitive impairment may be subtle at first, it eventually becomes apparent that affected individuals have a progressive dementia. Older teenagers and young adults may present predominantly with apparent early-onset dementia or psychiatric manifestations; however, careful examination usually identifies typical neurologic signs.
Amyotrophic lateral sclerosis 15, with or without frontotemporal dementia
MedGen UID:
477090
Concept ID:
C3275459
Disease or Syndrome
Any amyotrophic lateral sclerosis in which the cause of the disease is a mutation in the UBQLN2 gene.
Spastic paraplegia 47, autosomal recessive
MedGen UID:
481368
Concept ID:
C3279738
Disease or Syndrome
AP-4-associated hereditary spastic paraplegia (HSP), also known as AP-4 deficiency syndrome, is a group of neurodegenerative disorders characterized by a progressive, complex spastic paraplegia with onset typically in infancy or early childhood. Early-onset hypotonia evolves into progressive lower-extremity spasticity. The majority of children become nonambulatory and usually wheelchair bound. Over time spasticity progresses to involve the upper extremities, resulting in a spastic tetraplegia. Associated complications include dysphagia, contractures, foot deformities, dysregulation of bladder and bowel function, and a pseudobulbar affect. About 50% of affected individuals have seizures. Postnatal microcephaly (usually in the -2SD to -3SD range) is common. All have developmental delay. Speech development is significantly impaired and many affected individuals remain nonverbal. Intellectual disability in older children is usually moderate to severe.
Methylmalonate semialdehyde dehydrogenase deficiency
MedGen UID:
481470
Concept ID:
C3279840
Disease or Syndrome
Methylmalonate semialdehyde dehydrogenase deficiency is a rare autosomal recessive inborn error of metabolism with a highly variable phenotype. Some patients may be asymptomatic, whereas others show global developmental delay, nonspecific dysmorphic features, and delayed myelination on brain imaging. Laboratory studies typically show increased urinary 3-hydroxyisobutyric acid, although additional metabolic abnormalities may also be observed (summary by Marcadier et al., 2013).
Neurodevelopmental disorder with or without hyperkinetic movements and seizures, autosomal dominant
MedGen UID:
481912
Concept ID:
C3280282
Disease or Syndrome
GRIN1-related neurodevelopmental disorder (GRIN1-NDD) is characterized by mild-to-profound developmental delay / intellectual disability (DD/ID) in all affected individuals. Other common manifestations are epilepsy, muscular hypotonia, movement disorders, spasticity, feeding difficulties, and behavior problems. A subset of individuals show a malformation of cortical development consisting of extensive and diffuse bilateral polymicrogyria. To date, 72 individuals with GRIN1-NDD have been reported.
Neurodegeneration with brain iron accumulation 4
MedGen UID:
482001
Concept ID:
C3280371
Disease or Syndrome
Mitochondrial membrane protein-associated neurodegeneration (MPAN) is characterized initially by gait changes followed by progressive spastic paresis, progressive dystonia (which may be limited to the hands and feet or more generalized), neuropsychiatric abnormalities (emotional lability, depression, anxiety, impulsivity, compulsions, hallucinations, perseveration, inattention, and hyperactivity), and cognitive decline. Additional early findings can include dysphagia, dysarthria, optic atrophy, axonal neuropathy, parkinsonism, and bowel/bladder incontinence. Survival is usually well into adulthood. End-stage disease is characterized by severe dementia, spasticity, dystonia, and parkinsonism.
Microcephaly, cerebellar hypoplasia, and cardiac conduction defect syndrome
MedGen UID:
482322
Concept ID:
C3280692
Disease or Syndrome
The Zaki-Gleeson syndrome is an autosomal recessive neurodevelopmental disorder characterized by profound mental retardation, severe microcephaly, poor growth, cerebellar hypoplasia, and second-degree cardiac conduction defects (summary by Zaki et al., 2011).
Thiamine metabolism dysfunction syndrome 5 (episodic encephalopathy type)
MedGen UID:
482496
Concept ID:
C3280866
Disease or Syndrome
Episodic encephalopathy due to thiamine pyrophosphokinase deficiency is an autosomal recessive metabolic disorder due to an inborn error of thiamine metabolism. The phenotype is highly variable, but in general, affected individuals have onset in early childhood of acute encephalopathic episodes associated with increased serum and CSF lactate. These episodes result in progressive neurologic dysfunction manifest as gait disturbances, ataxia, dystonia, and spasticity, which in some cases may result in loss of ability to walk. Cognitive function is usually preserved, although mildly delayed development has been reported. These episodes are usually associated with infection and metabolic decompensation. Some patients may have recovery of some neurologic deficits (summary by Mayr et al., 2011). For a discussion of genetic heterogeneity of disorders due to thiamine metabolism dysfunction, see THMD1 (249270).
Spastic ataxia 5, autosomal recessive
MedGen UID:
482607
Concept ID:
C3280977
Disease or Syndrome
Spastic ataxia-5 (SPAX5) is an autosomal recessive neurodegenerative disorder characterized by early-onset spasticity resulting in significantly impaired ambulation, cerebellar ataxia, oculomotor apraxia, dystonia, and myoclonic epilepsy (summary by Pierson et al., 2011). For a discussion of genetic heterogeneity of spastic ataxia, see SPAX1 (108600).
Leukoencephalopathy, brain calcifications, and cysts
MedGen UID:
482830
Concept ID:
C3281200
Disease or Syndrome
Leukoencephalopathy, brain calcifications, and cysts (LCC), also known as Labrune syndrome, is characterized by a constellation of features restricted to the central nervous system, including leukoencephalopathy, brain calcifications, and cysts, resulting in spasticity, dystonia, seizures, and cognitive decline (summary by Labrune et al., 1996). See also cerebroretinal microangiopathy with calcifications and cysts (CRMCC; 612199), an autosomal recessive disorder caused by mutation in the CTC1 gene (613129) that shows phenotypic similarities to Labrune syndrome. CRMCC includes the neurologic findings of intracranial calcifications, leukodystrophy, and brain cysts, but also includes retinal vascular abnormalities and other systemic manifestations, such as osteopenia with poor bone healing, a high risk of gastrointestinal bleeding, hair, skin, and nail changes, and anemia and thrombocytopenia. Although Coats plus syndrome and Labrune syndrome were initially thought to be manifestations of the same disorder, namely CRMCC, molecular evidence has excluded mutations in the CTC1 gene in patients with Labrune syndrome, suggesting that the 2 disorders are not allelic (Anderson et al., 2012; Polvi et al., 2012).
Epileptic encephalopathy, early infantile, 1
MedGen UID:
483052
Concept ID:
C3463992
Disease or Syndrome
Developmental and epileptic encephalopathy-1 (DEE1) is a severe form of epilepsy characterized by frequent tonic seizures or spasms beginning in infancy with a specific EEG finding of suppression-burst patterns, characterized by high-voltage bursts alternating with almost flat suppression phases. Approximately 75% of DEE1 patients progress to tonic spasms with clustering, arrest of psychomotor development, and hypsarrhythmia on EEG (Kato et al., 2007). DEE1 is part of a phenotypic spectrum of disorders caused by mutation in the ARX gene comprising a nearly continuous series of developmental disorders ranging from lissencephaly (LISX2; 300215) to Proud syndrome (300004) to infantile spasms without brain malformations (DEE) to syndromic (309510) and nonsyndromic (300419) mental retardation. Although males with ARX mutations are often more severely affected, female mutation carriers may also be affected (Kato et al., 2004; Wallerstein et al., 2008). Reviews Deprez et al. (2009) reviewed the genetics of epilepsy syndromes starting in the first year of life and included a diagnostic algorithm. Genetic Heterogeneity of Developmental and Epileptic Encephalopathy Also see DEE2 (300672), caused by mutation in the CDKL5 gene (300203); DEE3 (609304), caused by mutation in the SLC25A22 gene (609302); DEE4 (612164), caused by mutation in the STXBP1 gene (602926); DEE5 (613477), caused by mutation in the SPTAN1 gene (182810); DEE6A (607208), also known as Dravet syndrome, caused by mutation in the SCN1A gene (182389); DEE6B (619317), also caused by mutation in the SCN1A gene; DEE7 (613720), caused by mutation in the KCNQ2 gene (602235); DEE8 (300607), caused by mutation in the ARHGEF9 gene (300429); DEE9 (300088), caused by mutation in the PCDH19 gene (300460); DEE10 (613402), caused by mutation in the PNKP gene (605610); DEE11 (613721), caused by mutation in the SCN2A gene (182390); DEE12 (613722), caused by mutation in the PLCB1 gene (607120); DEE13 (614558), caused by mutation in the SCN8A gene (600702); DEE14 (614959), caused by mutation in the KCNT1 gene (608167); DEE15 (615006), caused by mutation in the ST3GAL3 gene (606494); DEE16 (615338), caused by mutation in the TBC1D24 gene (613577); DEE17 (615473), caused by mutation in the GNAO1 gene (139311); DEE18 (615476), caused by mutation in the SZT2 gene (615463); DEE19 (615744), caused by mutation in the GABRA1 gene (137160); DEE20 (300868), caused by mutation in the PIGA gene (311770); DEE21 (615833), caused by mutation in the NECAP1 gene (611623); DEE22 (300896), caused by mutation in the SLC35A2 gene (314375); DEE23 (615859), caused by mutation in the DOCK7 gene (615730); DEE24 (615871), caused by mutation in the HCN1 gene (602780); DEE25 (615905), caused by mutation in the SLC13A5 gene (608305); DEE26 (616056), caused by mutation in the KCNB1 gene (600397); DEE27 (616139), caused by mutation in the GRIN2B gene (138252); DEE28 (616211), caused by mutation in the WWOX gene (605131); DEE29 (616339), caused by mutation in the AARS gene (601065); DEE30 (616341), caused by mutation in the SIK1 gene (605705); DEE31 (616346), caused by mutation in the DNM1 gene (602377); DEE32 (616366), caused by mutation in the KCNA2 gene (176262); DEE33 (616409), caused by mutation in the EEF1A2 gene (602959); DEE34 (616645), caused by mutation in the SLC12A5 gene (606726); DEE35 (616647), caused by mutation in the ITPA gene (147520); DEE36 (300884), caused by mutation in the ALG13 gene (300776); DEE37 (616981), caused by mutation in the FRRS1L gene (604574); DEE38 (617020), caused by mutation in the ARV1 gene (611647); DEE39 (612949), caused by mutation in the SLC25A12 gene (603667); DEE40 (617065), caused by mutation in the GUF1 gene (617064); DEE41 (617105), caused by mutation in the SLC1A2 gene (600300); DEE42 (617106), caused by mutation in the CACNA1A gene (601011); DEE43 (617113), caused by mutation in the GABRB3 gene (137192); DEE44 (617132), caused by mutation in the UBA5 gene (610552); DEE45 (617153), caused by mutation in the GABRB1 gene (137190); DEE46 (617162), caused by mutation in the GRIN2D gene (602717); DEE47 (617166), caused by mutation in the FGF12 gene (601513); DEE48 (617276), caused by mutation in the AP3B2 gene (602166); DEE49 (617281), caused by mutation in the DENND5A gene (617278); DEE50 (616457) caused by mutation in the CAD gene (114010); DEE51 (617339), caused by mutation in the MDH2 gene (154100); DEE52 (617350), caused by mutation in the SCN1B gene (600235); DEE53 (617389), caused by mutation in the SYNJ1 gene (604297); DEE54 (617391), caused by mutation in the HNRNPU gene (602869); DEE55 (617599), caused by mutation in the PIGP gene (605938); DEE56 (617665), caused by mutation in the YWHAG gene (605356); DEE57 (617771), caused by mutation in the KCNT2 gene (610044); DEE58 (617830), caused by mutation in the NTRK2 gene (600456); DEE59 (617904), caused by mutation in the GABBR2 gene (607340); DEE60 (617929), caused by mutation in the CNPY3 gene (610774); DEE61 (617933), caused by mutation in the ADAM22 gene (603709); DEE62 (617938), caused by mutation in the SCN3A gene (182391); DEE63 (617976), caused by mutation in the CPLX1 gene (605032); DEE64 (618004), caused by mutation in the RHOBTB2 gene (607352); DEE65 (618008), caused by mutation in the CYFIP2 gene (606323); DEE66 (618067), caused by mutation in the PACS2 gene (610423); DEE67 (618141), caused by mutation in the CUX2 gene (610648); DEE68 (618201), caused by mutation in the TRAK1 gene (608112); DEE69 (618285), caused by mutation in the CACNA1E gene (601013); DEE70 (618298) caused by mutation in the PHACTR1 gene (608723); DEE71 (618328), caused by mutation in the GLS gene (138280); DEE72 (618374), caused by mutation in the NEUROD2 gene (601725); DEE73 (618379), caused by mutation in the RNF13 gene (609247); DEE74 (618396), caused by mutation in the GABRG2 gene (137164); DEE75 (618437), caused by mutation in the PARS2 gene (612036); DEE76 (618468), caused by mutation in the ACTL6B gene (612458); DEE77 (618548), caused by mutation in the PIGQ gene (605754); DEE78 (618557), caused by mutation in the GABRA2 gene (137140); DEE79 (618559), caused by mutation in the GABRA5 gene (137142); DEE80 (618580), caused by mutation in the PIGB gene (604122); DEE81 (618663), caused by mutation in the DMXL2 gene (612186); DEE82 (618721), caused by mutation in the GOT2 gene (138150); DEE83 (618744), caused by mutation in the UGP2 gene (191760); DEE84 (618792), caused by mutation in the UGDH gene (603370); DEE85 (301044), caused by mutation in the SMC1A gene (300040); DEE86 (618910), caused by mutation in the DALRD3 gene (618904); DEE87 (618916), caused by mutation in the CDK19 gene (614720); DEE88 (618959), caused by mutation in the MDH1 gene (152400); DEE89 (619124), caused by mutation in the GAD1 gene (605363); DEE90 (301058), caused by mutation in the FGF13 gene (300070); DEE91 (617711), caused by mutation in the PPP3CA gene (114105); DEE92 (617829), caused by mutation in the GABRB2 gene (600232); DEE93 (618012), caused by mutation in the ATP6V1A gene (607027), DEE94 (615369), caused by mutation in the CHD2 gene (602119); DEE95 (618143), caused by mutation in the PIGS gene (610271); and DEE96 (619340), caused by mutation in the NSF gene (601633). The phenotype is also observed in other genetic disorders, including GLUT1 deficiency syndrome (606777); glycine encephalopathy (605899); Aicardi-Goutieres syndrome (225750); and in males with MECP2 mutations (300673), among others. For associations pending confirmation, see MOLECULAR GENETICS.
Aicardi Goutieres syndrome 2
MedGen UID:
483677
Concept ID:
C3489724
Disease or Syndrome
Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known.
Spastic paraplegia 35
MedGen UID:
501249
Concept ID:
C3496228
Disease or Syndrome
Fatty acid hydroxylase-associated neurodegeneration (FAHN) is characterized early in the disease course by central nervous system involvement including corticospinal tract involvement (spasticity), mixed movement disorder (ataxia/dystonia), and eye findings (optic atrophy, oculomotor abnormalities), and later in the disease course by progressive intellectual impairment and seizures. With disease progression, dystonia and spasticity compromise the ability to ambulate, leading to wheelchair dependence. Life expectancy is variable. FAHN is considered to be a subtype of neurodegeneration with brain iron accumulation (NBIA).
Aicardi-Goutieres syndrome 6
MedGen UID:
761287
Concept ID:
C3539013
Disease or Syndrome
Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known.
Spastic paraplegia 53, autosomal recessive
MedGen UID:
761340
Concept ID:
C3539494
Disease or Syndrome
SPG53 is an autosomal recessive neurologic disorder characterized by onset in infancy of delayed motor development progressing to upper and lower limb spasticity with impaired walking. Affected individuals also show mild to moderate cognitive impairment (summary by Zivony-Elboum et al., 2012).
Alternating hemiplegia of childhood 1
MedGen UID:
762361
Concept ID:
C3549447
Disease or Syndrome
Alternating hemiplegia of childhood is a rare syndrome of episodic hemi- or quadriplegia lasting minutes to days. Most cases are accompanied by dystonic posturing, choreoathetoid movements, nystagmus, other ocular motor abnormalities, autonomic disturbances, and progressive cognitive impairment (Mikati et al., 1992). The disorder may mimic or overlap with other disorders, including familial hemiplegic migraine (FHM1; 141500) and GLUT1 deficiency syndrome (606777) (Rotstein et al., 2009). Genetic Heterogeneity of Alternating Hemiplegia of Childhood See also AHC2 (614820), caused by mutation in the ATP1A3 gene (182350).
Neurodegeneration with brain iron accumulation 5
MedGen UID:
763887
Concept ID:
C3550973
Disease or Syndrome
Beta-propeller protein-associated neurodegeneration (BPAN) is typically characterized by early-onset seizures, infantile-onset developmental delay, intellectual disability, absent to limited expressive language, motor dysfunction (ataxia), and abnormal behaviors often similar to autism spectrum disorder. Seizure types including generalized (absence, tonic, atonic, tonic-clonic and myoclonic), focal with impaired consciousness, and epileptic spasms, as well as epileptic syndromes (West syndrome and Lennox-Gastaut syndrome) can be seen. With age seizures tend to resolve or become less prominent, whereas cognitive decline and movement disorders (progressive parkinsonism and dystonia) emerge as characteristic findings.
Coenzyme Q10 deficiency, primary, 5
MedGen UID:
766288
Concept ID:
C3553374
Disease or Syndrome
Primary coenzyme Q10 (CoQ10) deficiency is usually associated with multisystem involvement, including neurologic manifestations such as fatal neonatal encephalopathy with hypotonia; a late-onset slowly progressive multiple-system atrophy-like phenotype (neurodegeneration with autonomic failure and various combinations of parkinsonism and cerebellar ataxia, and pyramidal dysfunction); and dystonia, spasticity, seizures, and intellectual disability. Steroid-resistant nephrotic syndrome (SRNS), the hallmark renal manifestation, is often the initial manifestation either as isolated renal involvement that progresses to end-stage renal disease (ESRD), or associated with encephalopathy (seizures, stroke-like episodes, severe neurologic impairment) resulting in early death. Hypertrophic cardiomyopathy (HCM), retinopathy or optic atrophy, and sensorineural hearing loss can also be seen.
Combined oxidative phosphorylation deficiency 10
MedGen UID:
766443
Concept ID:
C3553529
Disease or Syndrome
COXPD10 is an autosomal recessive disorder resulting in variable defects of mitochondrial oxidative respiration. Affected individuals present in infancy with hypertrophic cardiomyopathy and lactic acidosis. The severity is variable, but can be fatal in the most severe cases (summary by Ghezzi et al., 2012). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
3-methylglutaconic aciduria with deafness, encephalopathy, and Leigh-like syndrome
MedGen UID:
766511
Concept ID:
C3553597
Disease or Syndrome
The phenotypic spectrum of SERAC1 deficiency comprises MEGD(H)EL syndrome (3-methylglutaconic aciduria with deafness-dystonia, [hepatopathy], encephalopathy, and Leigh-like syndrome), juvenile-onset complicated hereditary spastic paraplegia (in 1 consanguineous family), and adult-onset generalized dystonia (in 1 adult male). MEGD(H)EL syndrome is characterized in neonates by hypoglycemia and a sepsis-like clinical picture for which no infectious agent can be found. During the first year of life feeding problems, failure to thrive, and/or truncal hypotonia become evident; many infants experience (transient) liver involvement ranging from undulating transaminases to prolonged hyperbilirubinemia and near-fatal liver failure. By age two years progressive deafness, dystonia, and spasticity prevent further psychomotor development and/or result in loss of acquired skills. Affected children are completely dependent on care for all activities of daily living; speech is absent.
Alternating hemiplegia of childhood 2
MedGen UID:
766702
Concept ID:
C3553788
Disease or Syndrome
ATP1A3-related neurologic disorders represent a clinical continuum in which at least three distinct phenotypes have been delineated: rapid-onset dystonia-parkinsonism (RDP); alternating hemiplegia of childhood (ACH); and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS). However, some affected individuals have intermediate phenotypes or only a few features that do not fit well into one of these major phenotypes. RDP has been characterized by: abrupt onset of dystonia over days to weeks with parkinsonism (primarily bradykinesia and postural instability); common bulbar involvement; and absence or minimal response to an adequate trial of L-dopa therapy, with few exceptions. Often fever, physiologic stress, or alcoholic binges trigger the onset of symptoms. After their initial appearance, symptoms often stabilize with little improvement; occasionally second episodes occur with abrupt worsening of symptoms. Rarely, affected individuals have reported a more gradual onset of symptoms over weeks to months. Anxiety, depression, and seizures have been reported. Age of onset ranges from four to 55 years, although a childhood variation of RDP with onset between ages nine and 14 months has been reported. AHC is a complex neurodevelopmental syndrome most frequently manifesting in infancy or early childhood with paroxysmal episodic neurologic dysfunction including alternating hemiparesis or dystonia, quadriparesis, seizure-like episodes, and oculomotor abnormalities. Episodes can last for minutes, hours, days, or even weeks. Remission of symptoms occurs with sleep and immediately after awakening. Over time, persistent neurologic deficits including oculomotor apraxia, ataxia, choreoathetosis, dystonia, parkinsonism, and cognitive and behavioral dysfunction develop in the majority of those affected; more than 50% develop epilepsy in addition to their episodic movement disorder phenotype. CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) syndrome is characterized by episodes of ataxic encephalopathy and/or weakness during and after a febrile illness. Onset is between ages six months and four years. Some acute symptoms resolve; progression of sensory losses and severity vary.
Combined oxidative phosphorylation deficiency 12
MedGen UID:
766993
Concept ID:
C3554079
Disease or Syndrome
COXPD12 is an autosomal recessive mitochondrial neurologic disorder characterized by onset in infancy of hypotonia and delayed psychomotor development, or early developmental regression, associated with T2-weighted hyperintensities in the deep cerebral white matter, brainstem, and cerebellar white matter. Serum lactate is increased due to a defect in mitochondrial respiration. There are 2 main phenotypic groups: those with a milder disease course and some recovery of skills after age 2 years, and those with a severe disease course resulting in marked disability (summary by Steenweg et al., 2012). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
Combined oxidative phosphorylation deficiency 13
MedGen UID:
767043
Concept ID:
C3554129
Disease or Syndrome
Combined oxidative phosphorylation deficiency-13 is an autosomal recessive multisystem disorder resulting from mitochondrial dysfunction. Affected individuals develop severe neurologic impairment in the first months of life, including hypotonia, abnormal dystonic movements, hearing loss, poor feeding, global developmental delay, and abnormal eye movements. Brain imaging shows signal abnormalities in putamen, basal ganglia, caudate nuclei, or corpus callosum, as well as delayed myelination. Analysis of patient tissues shows multiple defects in enzymatic activities of the mitochondrial respiratory chain, although some tissues may show normal values since tissue expression of the mitochondrial defect and metabolic needs of specific tissues are variable (summary by Vedrenne et al., 2012).
Mitochondrial complex III deficiency, nuclear type 2
MedGen UID:
767519
Concept ID:
C3554605
Disease or Syndrome
Mitochondrial complex III deficiency nuclear type 2 is an autosomal recessive severe neurodegenerative disorder that usually presents in childhood, but may show later onset, even in adulthood. Affected individuals have motor disability, with ataxia, apraxia, dystonia, and dysarthria, associated with necrotic lesions throughout the brain. Most patients also have cognitive impairment and axonal neuropathy and become severely disabled later in life (summary by Ghezzi et al., 2011). The disorder may present clinically as spinocerebellar ataxia or Leigh syndrome, or with psychiatric disturbances (Morino et al., 2014; Atwal, 2014; Nogueira et al., 2013). For a discussion of genetic heterogeneity of mitochondrial complex III deficiency, see MC3DN1 (124000).
Mitochondrial complex III deficiency, nuclear type 4
MedGen UID:
767521
Concept ID:
C3554607
Disease or Syndrome
The severity of mitochondrial complex III deficiency varies widely among affected individuals. People who are mildly affected tend to have muscle weakness (myopathy) and extreme tiredness (fatigue), particularly during exercise (exercise intolerance). More severely affected individuals have problems with multiple body systems, such as liver disease that can lead to liver failure, kidney abnormalities (tubulopathy), and brain dysfunction (encephalopathy). Encephalopathy can cause delayed development of mental and motor skills (psychomotor delay), movement problems, weak muscle tone (hypotonia), and difficulty with communication. Some affected individuals have a form of heart disease called cardiomyopathy, which can lead to heart failure. Most people with mitochondrial complex III deficiency have a buildup of a chemical called lactic acid in the body (lactic acidosis). Some affected individuals also have buildup of molecules called ketones (ketoacidosis) or high blood sugar levels (hyperglycemia). Abnormally high levels of these chemicals in the body can be life-threatening.\n\nMitochondrial complex III deficiency is a genetic condition that can affect several parts of the body, including the brain, kidneys, liver, heart, and the muscles used for movement (skeletal muscles). Signs and symptoms of mitochondrial complex III deficiency usually begin in infancy but can appear later.\n\nMitochondrial complex III deficiency can be fatal in childhood, although individuals with mild signs and symptoms can survive into adolescence or adulthood.
Chromosome Xq28 deletion syndrome
MedGen UID:
812964
Concept ID:
C3806634
Disease or Syndrome
Deafness, dystonia, and cerebral hypomyelination is an X-linked recessive mental retardation syndrome characterized by almost no psychomotor development, dysmorphic facial features, sensorineural deafness, dystonia, pyramidal signs, and hypomyelination on brain imaging (summary by Cacciagli et al., 2013).
Early infantile epileptic encephalopathy 16
MedGen UID:
815503
Concept ID:
C3809173
Disease or Syndrome
TBC1D24-related disorders comprise a continuum of features that were originally described as distinct, recognized phenotypes: DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation, and seizures). Profound sensorineural hearing loss, onychodystrophy, osteodystrophy, intellectual disability / developmental delay, and seizures. Familial infantile myoclonic epilepsy (FIME). Early-onset myoclonic seizures, focal epilepsy, dysarthria, and mild-to-moderate intellectual disability. Progressive myoclonus epilepsy (PME). Action myoclonus, tonic-clonic seizures, progressive neurologic decline, and ataxia. Early-infantile epileptic encephalopathy 16 (EIEE16). Epileptiform EEG abnormalities which themselves are believed to contribute to progressive disturbance in cerebral function. Autosomal recessive nonsyndromic hearing loss, DFNB86. Profound prelingual deafness. Autosomal dominant nonsyndromic hearing loss, DFNA65. Slowly progressive deafness with onset in the third decade, initially affecting the high frequencies.
Mitochondrial DNA depletion syndrome 13 (encephalomyopathic type)
MedGen UID:
815922
Concept ID:
C3809592
Disease or Syndrome
FBXL4-related encephalomyopathic mitochondrial DNA (mtDNA) depletion syndrome is a multi-system disorder characterized primarily by congenital or early-onset lactic acidosis and growth failure, feeding difficulty, hypotonia, and developmental delay. Other neurologic manifestations can include seizures, movement disorders, ataxia, autonomic dysfunction, and stroke-like episodes. All affected individuals alive at the time they were reported (median age: 3.5 years) demonstrated significant developmental delay. Other findings can involve the heart (hypertrophic cardiomyopathy, congenital heart malformations, arrhythmias), liver (mildly elevated transaminases), eyes (cataract, strabismus, nystagmus, optic atrophy), hearing (sensorineural hearing loss), and bone marrow (neutropenia, lymphopenia). Survival varies; the median age of reported deaths was two years (range 2 days – 75 months), although surviving individuals as old as 36 years have been reported. To date FBXL4-related mtDNA depletion syndrome has been reported in 50 individuals.
Early infantile epileptic encephalopathy 17
MedGen UID:
815936
Concept ID:
C3809606
Disease or Syndrome
Developmental and epileptic encephalopathy-17 (DEE17) is a severe neurologic disorder characterized by onset of intractable seizures in the first weeks or months of life. EEG often shows a burst-suppression pattern consistent with a clinical diagnosis of Ohtahara syndrome. Affected infants have very poor psychomotor development and may have brain abnormalities, such as cerebral atrophy or thin corpus callosum. Some patients may show involuntary movements (summary by Nakamura et al., 2013). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Parkinson disease 19a, juvenile-onset
MedGen UID:
816141
Concept ID:
C3809811
Disease or Syndrome
DNAJC6 Parkinson disease is a complex early-onset neurologic disorder whose core features are typical parkinsonian symptoms including bradykinesia, resting tremor, rigidity, and postural instability. The majority of individuals have juvenile onset and develop symptoms before age 21 years. Developmental delay, intellectual disability, seizures, other movement disorders (e.g., dystonia, spasticity, myoclonus), and neuropsychiatric features occur in the majority of individuals with juvenile onset and often precede parkinsonism. The onset of parkinsonian features usually occurs toward the end of the first or beginning of the second decade and the disease course is rapidly progressive with loss of ambulation in mid-adolescence in the majority of individuals. Additional features include gastrointestinal manifestations and bulbar dysfunction. A minority of individuals with DNAJC6 Parkinson disease develop early-onset parkinsonism with symptom onset in the third to fourth decade and absence of additional neurologic features.
Parkinson disease 20, early-onset
MedGen UID:
816154
Concept ID:
C3809824
Disease or Syndrome
Parkinson disease-20 is an autosomal recessive neurodegenerative disorder characterized by young adult-onset of parkinsonism. Additional features may include seizures, cognitive decline, abnormal eye movements, and dystonia (summary by Krebs et al., 2013 and Quadri et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of Parkinson disease, see PD (168600).
Neurodegeneration with brain iron accumulation 6
MedGen UID:
816560
Concept ID:
C3810230
Disease or Syndrome
Neurodegeneration with brain iron accumulation refers to a group of neurodegenerative disorders characterized by progressive motor and cognitive dysfunction beginning in childhood or young adulthood. Patients show extrapyramidal motor signs, such as spasticity, dystonia, and parkinsonism. Brain imaging shows iron accumulation in the basal ganglia (summary by Dusi et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of NBIA, see NBIA1 (234200).
Myopathy with extrapyramidal signs
MedGen UID:
816615
Concept ID:
C3810285
Disease or Syndrome
Myopathy with extrapyramidal signs is an autosomal recessive disorder characterized by early childhood onset of proximal muscle weakness and learning disabilities. While the muscle weakness is static, most patients develop progressive extrapyramidal signs that may become disabling (summary by Logan et al., 2014). Brain MRI in 1 patient showed congenital malformations, including polymicrogyria and cerebellar dysplasia (Wilton et al., 2020).
Aicardi-Goutieres syndrome 7
MedGen UID:
854829
Concept ID:
C3888244
Disease or Syndrome
Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known.
Ataxia-telangiectasia-like disorder 1
MedGen UID:
861227
Concept ID:
C4012790
Disease or Syndrome
Ataxia-telangiectasia-like disorder-1 is an autosomal recessive disorder characterized clinically by progressive cerebellar degeneration resulting in ataxia and oculomotor apraxia. Laboratory studies of patient cells showed increased susceptibility to radiation, consistent with a defect in DNA repair. The disorder shares some phenotypic features of ataxia-telangiectasia (AT; 208900), but telangiectases and immune deficiency are not present in ATLD1 (summary by Hernandez et al., 1993 and Stewart et al., 1999). Genetic Heterogeneity of Ataxia-Telangiectasia-Like Disorder See also ATLD2 (615919), caused by mutation in the PCNA gene (176740) on chromosome 20p12.
Leukoencephalopathy, progressive, with ovarian failure
MedGen UID:
863025
Concept ID:
C4014588
Disease or Syndrome
Progressive leukoencephalopathy with ovarian failure is an autosomal recessive neurodegenerative disorder characterized by loss of motor and cognitive skills, usually with onset in young adulthood. Some patients may have a history of delayed motor development or learning difficulties in early childhood. Neurologic decline is severe, usually resulting in gait difficulties, ataxia, spasticity, and cognitive decline and dementia. Most patients lose speech and become wheelchair-bound or bedridden. Brain MRI shows progressive white matter signal abnormalities in the deep white matter. Affected females develop premature ovarian failure (summary by Dallabona et al., 2014).
Encephalopathy, progressive, with or without lipodystrophy
MedGen UID:
863137
Concept ID:
C4014700
Disease or Syndrome
The spectrum of BSCL2-related neurologic disorders includes Silver syndrome and variants of Charcot-Marie-Tooth neuropathy type 2, distal hereditary motor neuropathy (dHMN) type V, and spastic paraplegia 17. Features of these disorders include onset of symptoms ranging from the first to the seventh decade, slow disease progression, upper motor neuron involvement (gait disturbance with pyramidal signs ranging from mild to severe spasticity with hyperreflexia in the lower limbs and variable extensor plantar responses), lower motor neuron involvement (amyotrophy of the peroneal muscles and small muscles of the hand), and pes cavus and other foot deformities. Disease severity is variable among and within families.
Polyendocrine-polyneuropathy syndrome
MedGen UID:
863698
Concept ID:
C4015261
Disease or Syndrome
Epileptic encephalopathy, early infantile, 27
MedGen UID:
863753
Concept ID:
C4015316
Disease or Syndrome
GRIN2B-related neurodevelopmental disorder is characterized by mild to profound developmental delay / intellectual disability (DD/ID) in all affected individuals. Muscle tone abnormalities (spasticity and/or hypotonia, occasionally associated with feeding difficulties), as well as epilepsy and autism spectrum disorder (ASD) / behavioral issues, are common. Other infantile- or childhood-onset findings include microcephaly; dystonic, dyskinetic, or choreiform movement disorder; and/or cortical visual impairment. Brain MRI reveals a malformation of cortical development in a minority of affected individuals. To date, fewer than 100 individuals with GRIN2B-related neurodevelopmental disorder have been reported.
Recurrent metabolic encephalomyopathic crises-rhabdomyolysis-cardiac arrhythmia-intellectual disability syndrome
MedGen UID:
894196
Concept ID:
C4225171
Disease or Syndrome
Individuals with TANGO2-related metabolic encephalopathy and arrhythmias can present in acute metabolic crisis (hypoglycemia, elevated lactate, mild hyperammonemia) or with developmental delay, regression, and/or seizures. The acute presentation varies from profound muscle weakness, ataxia, and/or disorientation to a comatose state. Individuals can present with intermittent acute episodes of rhabdomyolysis. The first episode of myoglobinuria has been known to occur as early as age five months. Acute renal tubular damage due to myoglobinuria can result in acute kidney injury and renal failure. During acute illness, transient electrocardiogram changes can be seen; the most common is QT prolongation. Life-threatening recurrent ventricular tachycardia or torsade de pointes occurs primarily during times of acute illness. Individuals who do not present in metabolic crises may present with gait incoordination, progressively unsteady gait, difficulty with speech, or clumsiness. Intellectual disability of variable severity is observed in almost all individuals. Seizures are observed outside the periods of crises in more than 75% of individuals. Hypothyroidism has been reported in more than one third of individuals.
Cerebellar atrophy, visual impairment, and psychomotor retardation
MedGen UID:
905041
Concept ID:
C4225172
Disease or Syndrome
Combined oxidative phosphorylation deficiency 29
MedGen UID:
901598
Concept ID:
C4225200
Disease or Syndrome
Leukodystrophy and acquired microcephaly with or without dystonia
MedGen UID:
908888
Concept ID:
C4225213
Disease or Syndrome
Spastic paraplegia and psychomotor retardation with or without seizures
MedGen UID:
897828
Concept ID:
C4225215
Disease or Syndrome
Spastic paraplegia and psychomotor retardation with or without seizures is an autosomal recessive complex neurodevelopmental disorder with onset in infancy. Affected children show hypotonia followed by severely impaired global development and significant motor disability. Most develop seizures in childhood and have speech delay. Other features, such as ocular abnormalities, foot deformities, hypoplasia of the corpus callosum, and decreased white matter, are more variable (summary by Hollstein et al., 2015).
Charcot-Marie-Tooth disease, type 4k
MedGen UID:
895560
Concept ID:
C4225246
Disease or Syndrome
Charcot-Marie-Tooth disease type 4K is an autosomal recessive demyelinating peripheral neuropathy characterized by onset in the first decade of distal muscle weakness and atrophy associated with impaired distal sensation. Both upper and lower limbs are affected. Affected individuals may also have nystagmus and late-onset cerebellar ataxia. Laboratory studies show increased serum lactate and isolated mitochondrial complex IV deficiency (summary by Echaniz-Laguna et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive demyelinating Charcot-Marie-Tooth disease, see CMT4A (214400).
Combined oxidative phosphorylation deficiency 27
MedGen UID:
908541
Concept ID:
C4225251
Disease or Syndrome
Any combined oxidative phosphorylation deficiency in which the cause of the disease is a mutation in the CARS2 gene.
Epileptic encephalopathy, early infantile, 29
MedGen UID:
908570
Concept ID:
C4225361
Disease or Syndrome
Developmental and epileptic encephalopathy-29 (DEE29) is an autosomal recessive neurologic disorder characterized by the onset of refractory myoclonic seizures in the first months of life. Affected individuals have poor overall growth, congenital microcephaly with cerebral atrophy and impaired myelination on brain imaging, spasticity with abnormal movements, peripheral neuropathy, and poor visual fixation (summary by Simons et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Lipoyltransferase 1 deficiency
MedGen UID:
904073
Concept ID:
C4225379
Disease or Syndrome
Lipoyl transferase 1 deficiency is a very rare inborn error of metabolism disorder, with a highly variable phenotype, typically characterized by neonatal to infancy-onset of seizures, psychomotor delay, and abnormal muscle tone that may include hypo- and/or hypertonia, resulting in generalized weakness, dystonic movements, and/or progressive respiratory distress, associated with severe lactic acidosis and elevated lactate, ketoglutarate and 2-oxoacids in urine. Additional manifestations may include dehydration, vomiting, signs of liver dysfunction, extrapyramidal signs, spastic tetraparesis, brisk deep tendon reflexes, speech impairment, swallowing difficulties, and pulmonary hypertension.
Mitochondrial short-chain enoyl-coa hydratase 1 deficiency
MedGen UID:
902729
Concept ID:
C4225391
Disease or Syndrome
Mitochondrial short-chain enoyl-CoA hydratase 1 deficiency (ECHS1D) represents a clinical spectrum in which several phenotypes have been described: The most common phenotype presents in the neonatal period with severe encephalopathy and lactic acidosis and later manifests Leigh-like signs and symptoms. Those with presentation in the neonatal period typically have severe hypotonia, encephalopathy, or neonatal seizures within the first few days of life. Signs and symptoms typically progress quickly and the affected individual ultimately succumbs to central apnea or arrhythmia. A second group of affected individuals present in infancy with developmental regression resulting in severe developmental delay. A third group of affected individuals have normal development with isolated paroxysmal dystonia that may be exacerbated by illness or exertion. Across all three groups, T2 hyperintensity in the basal ganglia is very common, and may affect any part of the basal ganglia.
Ataxia-oculomotor apraxia 4
MedGen UID:
902323
Concept ID:
C4225397
Disease or Syndrome
Ataxia-oculomotor apraxia-4 (AOA4) is an autosomal recessive neurologic disorder characterized by onset of dystonia and ataxia in the first decade. Additional features include oculomotor apraxia and peripheral neuropathy. Some patients may show cognitive impairment. The disorder is progressive, and most patients become wheelchair-bound in the second or third decade (summary by Bras et al., 2015). For a discussion of genetic heterogeneity of ataxia-oculomotor apraxia, see AOA1 (208920).
Mental retardation, X-linked, syndromic 33
MedGen UID:
895979
Concept ID:
C4225418
Disease or Syndrome
X-linked syndromic intellectual developmental disorder-33 (MRXS33) is an X-linked recessive neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability, and characteristic facial features (summary by O'Rawe et al., 2015).
Dystonia 28, childhood-onset
MedGen UID:
934600
Concept ID:
C4310633
Disease or Syndrome
KMT2B-related dystonia (DYT-KMT2B) is a complex childhood-onset (mean age 7 years) movement disorder described to date in 39 individuals. It is characterized by a progressive disease course evolving commonly from lower-limb focal dystonia into generalized dystonia with prominent cervical, cranial, and laryngeal involvement. Communication difficulties, secondary to articulation difficulties and low speech volume, are common. Bulbar dysfunction leads to impaired swallowing. Intellectual disability (ID) / developmental delay (DD) are commonly reported. Additional findings can include eye movement abnormalities, skin changes, psychiatric comorbidities (attention-deficit/hyperactivity disorder, anxiety, depression, and obsessive-compulsive disorder), myoclonus, seizures, spasticity, and sensorineural hearing loss. Many affected individuals follow a similar disease course, though milder and atypical findings have been described.
Dystonia, childhood-onset, with optic atrophy and basal ganglia abnormalities
MedGen UID:
934601
Concept ID:
C4310634
Disease or Syndrome
MECR-related neurologic disorder is characterized by a progressive childhood-onset movement disorder and optic atrophy; intellect is often – but not always – preserved. The movement disorder typically presents between ages one and 6.5 years and is mainly dystonia that can be accompanied by chorea and/or ataxia. Over time some affected individuals require assistive devices for mobility. Speech fluency and intelligibility are progressively impaired due to dysarthria. Optic atrophy typically develops between ages four and 12 years and manifests as reduced visual acuity, which can include functional blindness (also known as legal blindness) in adulthood. Because only 13 affected individuals are known to the authors, and because nearly half of them were diagnosed retrospectively as adults, the natural history of disease progression and other aspects of the phenotype have not yet been completely defined.
3-methylglutaconic aciduria, type VIII
MedGen UID:
934617
Concept ID:
C4310650
Disease or Syndrome
MGCA8 is an autosomal recessive metabolic disorder resulting in death in infancy. Features include hypotonia, abnormal movements, respiratory insufficiency with apneic episodes, and lack of developmental progress, often with seizures. Brain imaging is variable, but may show progressive cerebral atrophy. Laboratory studies show increased serum lactate and 3-methylglutaconic aciduria, suggesting a mitochondrial defect (summary by Mandel et al., 2016). For a phenotypic description and a discussion of genetic heterogeneity of 3-methylglutaconic aciduria, see MGCA type I (250950).
Neurodegeneration with ataxia, dystonia, and gaze palsy, childhood-onset
MedGen UID:
934660
Concept ID:
C4310693
Disease or Syndrome
Childhood-onset neurodegeneration with ataxia, dystonia, and gaze palsy is an autosomal recessive progressive disorder characterized by onset of gait ataxia, cognitive decline, and gaze palsy in the first or second decades. Additional features include dysarthria, dystonia, and athetoid movements. Some patients may become wheelchair-bound as young adults (summary by Haack et al., 2016).
Epileptic encephalopathy, early infantile, 44
MedGen UID:
934667
Concept ID:
C4310700
Disease or Syndrome
Developmental and epileptic encephalopathy-44 (DEE44) is an autosomal recessive neurologic disorder characterized by the onset of refractory infantile spasms or myoclonus usually in the first weeks or months of life, up to about 12 months of age. Affected infants may have normal or mildly delayed development before the onset of seizures, but thereafter show developmental stagnation and severe neurologic impairment. EEG in some patients shows hypsarrhythmia, consistent with a clinical diagnosis of West syndrome. Additional features include poor feeding and poor overall growth with microcephaly, axial hypotonia with peripheral hypertonia or spasticity, abnormal movements, limited eye contact, and profoundly impaired intellectual development with absent language. Many patients require tube feeding, and some die in childhood (summary by Muona et al., 2016; Colin et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Striatonigral degeneration, childhood-onset
MedGen UID:
934710
Concept ID:
C4310743
Disease or Syndrome
A rare genetic neurodegenerative disease characterized by sudden onset of progressive motor deterioration and regression of developmental milestones. Manifestations include dystonia and muscle spasms, dysphagia, dysarthria, and eventually loss of speech and ambulation. Brain MRI shows predominantly striatal abnormalities. The disease is potentially associated with a fatal outcome.
Hermansky-Pudlak syndrome 10
MedGen UID:
934713
Concept ID:
C4310746
Disease or Syndrome
Hermansky-Pudlak syndrome (HPS) is characterized by oculocutaneous albinism, a bleeding diathesis, and, in some individuals, pulmonary fibrosis, granulomatous colitis, or immunodeficiency. Ocular findings include reduced iris pigment with iris transillumination, reduced retinal pigment, foveal hypoplasia with significant reduction in visual acuity (usually in the range of 20/50 to 20/400), nystagmus, and increased crossing of the optic nerve fibers. Hair color ranges from white to brown; skin color ranges from white to olive and is usually a shade lighter than that of other family members. The bleeding diathesis can result in variable bruising, epistaxis, gingival bleeding, postpartum hemorrhage, colonic bleeding, and prolonged bleeding with menses or after tooth extraction, circumcision, and other surgeries. Pulmonary fibrosis, a restrictive lung disease, typically causes symptoms in the early thirties and can progress to death within a decade. Granulomatous colitis is severe in about 15% of affected individuals. Neutropenia and/or immune defects occur primarily in individuals with pathogenic variants in AP3B1 and AP3D1.
Epileptic encephalopathy, early infantile, 38
MedGen UID:
934729
Concept ID:
C4310762
Disease or Syndrome
Developmental and epileptic encephalopathy-38 (DEE38) is an autosomal recessive neurologic and neurodegenerative disorder characterized by the onset of various type of seizures usually between about 4 and 7 months of age. Prior to the onset of seizures, most infants show severely impaired global development, hypotonia with poor head control, and visual inattention with roving eye movements and nystagmus. Seizures are usually refractory to treatment and associated with status epilepticus. Patients have little or no development with inability to walk or speak, spasticity or abnormal movements, and often cortical blindness. There is failure to thrive, and many require tube-feeding. Death in early childhood due to aspiration or intractable epilepsy may occur. The disorder is associated with a defect in GPI-anchoring of membrane-bound proteins (summary by Palmer et al., 2016; Davids et al., 2020). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350. For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293).
Hypermanganesemia with dystonia 2
MedGen UID:
934732
Concept ID:
C4310765
Disease or Syndrome
SLC39A14 deficiency is characterized by evidence between ages six months and three years of delay or loss of motor developmental milestones (e.g., delayed walking, gait disturbance). Early in the disease course, children show axial hypotonia followed by dystonia, spasticity, dysarthria, bulbar dysfunction, and signs of parkinsonism including bradykinesia, hypomimia, and tremor. By the end of the first decade they develop severe, generalized, pharmaco-resistant dystonia, limb contractures, and scoliosis, and lose independent ambulation. Cognitive impairment appears to be less prominent than motor disability. Some affected children have succumbed in their first decade due to secondary complications such as respiratory infections.
Epileptic encephalopathy, early infantile, 51
MedGen UID:
1372686
Concept ID:
C4479208
Disease or Syndrome
Developmental and epileptic encephalopathy-51 (DEE51) is an autosomal recessive severe neurodevelopmental disorder characterized by onset of intractable seizures and hypotonia in the first days or weeks of life. Affected individuals have severely delayed psychomotor development and may show abnormal movements. Brain imaging shows nonspecific abnormalities, such as cerebral atrophy, cerebellar atrophy, and delayed myelination. Laboratory studies showed increased lactate, suggesting mitochondrial dysfunction (summary by Ait-El-Mkadem et al., 2017). For a discussion of genetic heterogeneity of DEE, see 308350.
Cerebroretinal microangiopathy with calcifications and cysts 2
MedGen UID:
1390862
Concept ID:
C4479220
Disease or Syndrome
CRMCC2 is an autosomal recessive multisystem disorder characterized by premature aging, pancytopenia, hypocellular bone marrow, osteopenia, liver fibrosis, and vascular telangiectasia resulting in gastrointestinal bleeding. Brain imaging shows intracranial calcifications and leukodystrophy, which may result in neurologic signs including spasticity, ataxia, or dystonia. Patients may also have retinal telangiectasia (summary by Simon et al., 2016). For a discussion of genetic heterogeneity of CRMCC, see CRMCC1 (612199).
Hyperphenylalaninemia, mild, non-bh4-deficient
MedGen UID:
1391882
Concept ID:
C4479270
Disease or Syndrome
Mild non-BH4-deficient hyperphenylalaninemia (HPANBH4) is an autosomal recessive disorder characterized by increased serum phenylalanine (HPA) usually detected by newborn screening and associated with highly variable neurologic defects, including movement abnormalities, such as dystonia, and variably impaired intellectual development. Laboratory analysis shows dopamine and serotonin deficiencies in the cerebrospinal fluid, and normal tetrahydrobiopterin (BH4) metabolism. Evidence suggests that treatment with BH4 and neurotransmitter precursors can lead to clinical improvement or even prevent the neurologic defects if started in infancy (summary by Anikster et al., 2017). The phenotype is highly variable: some patients may present with later onset of juvenile or young adult nonprogressive dopa-responsive parkinsonism reminiscent of early-onset Parkinson disease (168600). These patients benefit from treatment with L-dopa (summary by Straniero et al., 2017). In a review of HPA, Blau et al. (2018) noted that molecular screening for DNAJC12 mutations should be mandatory in patients in whom deficiencies of PAH (612349) and BH4 metabolism have been excluded.
Lopes-Maciel-Rodan syndrome
MedGen UID:
1379711
Concept ID:
C4479491
Disease or Syndrome
Neurodevelopmental disorder with involuntary movements
MedGen UID:
1374697
Concept ID:
C4479569
Disease or Syndrome
NEDIM is a neurodevelopmental and neurodegenerative disorder characterized by delayed psychomotor development and infantile or childhood onset of hyperkinetic involuntary movements, including chorea and athetosis. The abnormal movements can be severe, sometimes resulting in inability to sit, walk, speak, or eat. Hyperkinetic movements can be exacerbated by specific triggers, such as stress, illness, or high temperature. Some patients have brain abnormalities, such as cerebral atrophy or thin corpus callosum, and some patients may develop seizures (summary by Ananth et al., 2016 and Danti et al., 2017).
Gabriele de Vries syndrome
MedGen UID:
1375401
Concept ID:
C4479652
Disease or Syndrome
Gabriele-de Vries syndrome is characterized by mild-to-profound developmental delay / intellectual disability (DD/ID) in all affected individuals and a wide spectrum of functional and morphologic abnormalities. Intrauterine growth restriction or low birth weight and feeding difficulties are common. Congenital brain, eye, heart, kidney, genital, and/or skeletal system anomalies have also been reported. About half of affected individuals have neurologic manifestations, including hypotonia and gait abnormalities. Behavioral issues can include attention-deficit/hyperactivity disorder, anxiety, autism or autistic behavior, and schizoaffective disorder.
Spastic ataxia 8, autosomal recessive, with hypomyelinating leukodystrophy
MedGen UID:
1382553
Concept ID:
C4479653
Disease or Syndrome
NKX6-2-related disorder is characterized by a spectrum of progressive neurologic manifestations resulting from diffuse central nervous system hypomyelination. At the severe end of the spectrum is neonatal-onset nystagmus, severe spastic tetraplegia with joint contractures and scoliosis, and visual and hearing impairment, all of which rapidly progress resulting in death in early childhood. At the milder end of the spectrum is normal achievement of early motor milestones in the first year of life followed by slowly progressive complex spastic ataxia with pyramidal findings (spasticity with increased muscle tone and difficulty with gait and fine motor coordination) and cerebellar findings (nystagmus, extraocular movement disorder, dysarthria, titubation, and ataxia) with loss of developmental milestones. To date NKX6-2-related disorder has been reported in 25 individuals from 13 families.
Limb-girdle muscular dystrophy, type 2S
MedGen UID:
1385598
Concept ID:
C4517996
Disease or Syndrome
Autosomal recessive limb-girdle muscular dystrophy-18 is characterized by childhood-onset of proximal muscle weakness resulting in gait abnormalities and scapular winging. Serum creatine kinase is increased. A subset of patients may show a hyperkinetic movement disorder with chorea, ataxia, or dystonia and global developmental delay (summary by Bogershausen et al., 2013). Additional more variable features include alacrima, achalasia, cataracts, or hepatic steatosis (Liang et al., 2015; Koehler et al., 2017). For discussion of genetic heterogeneity of autosomal recessive limb-girdle muscular dystrophy, see LGMDR1 (253600).
Diencephalic-mesencephalic junction dysplasia syndrome 1
MedGen UID:
1615973
Concept ID:
C4538630
Disease or Syndrome
Diencephalic-mesencephalic junction dysplasia syndrome-1 (DMJDS1) is an autosomal recessive neurodevelopmental disorder characterized by progressive microcephaly, severely delayed or even absent psychomotor development with profound intellectual disability, and spasticity or dystonia. Some patients may have seizures and/or visual impairment. Brain imaging shows a characteristic developmental malformation of the midbrain; subtle intracranial calcifications may also be present (summary by Aran et al., 2016 and Guemez-Gamboa et al., 2018). Genetic Heterogeneity of Diencephalic-Mesencephalic Junction Dysplasia Syndrome See also DMJDS2 (618646), caused by mutation in the GSX2 gene (616253) on chromosome 4q12.
Birk-Landau-Perez syndrome
MedGen UID:
1621949
Concept ID:
C4539828
Disease or Syndrome
Combined oxidative phosphorylation deficiency 32
MedGen UID:
1617600
Concept ID:
C4540029
Disease or Syndrome
Combined oxidative phosphorylation deficiency-32 is an autosomal recessive neurodegenerative disorder characterized by onset of delayed psychomotor development and developmental regression in infancy. Affected individuals have multiple variable symptoms, including poor or absent speech, inability to walk, and abnormal movements. Brain imaging shows T2-weighted abnormalities in the basal ganglia and brainstem consistent with Leigh syndrome (256000). Patient cells showed decreased activities of mitochondrial respiratory chain complexes, I, III, and IV, as well as impaired mitochondrial translation (summary by Lake et al., 2017). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
Encephalopathy, neonatal severe, with lactic acidosis and brain abnormalities
MedGen UID:
1624694
Concept ID:
C4540052
Disease or Syndrome
NELABA is a severe autosomal recessive metabolic disorder characterized by onset at birth of progressive encephalopathy associated with increased serum lactate. Affected individuals have little or no psychomotor development and show brain abnormalities, including cerebral atrophy, cysts, and white matter abnormalities. Some patients die in infancy (summary by Habarou et al., 2017).
Early-onset progressive encephalopathy-hearing loss-pons hypoplasia-brain atrophy syndrome
MedGen UID:
1622413
Concept ID:
C4540059
Disease or Syndrome
Childhood-onset motor and cognitive regression syndrome with extrapyramidal movement disorder
MedGen UID:
1626007
Concept ID:
C4540086
Disease or Syndrome
CONDBA is a severe progressive neurodegenerative disorder characterized by loss of motor and cognitive skills between ages 2 and 7 years. Affected individuals may have normal development or mild developmental delay, but all eventually lose all motor skills, resulting in inability to walk, absence of language, and profound intellectual disability. Brain imaging shows progressive cerebral and cerebellar atrophy (summary by Edvardson et al., 2017).
Neurodevelopmental disorder, mitochondrial, with abnormal movements and lactic acidosis, with or without seizures
MedGen UID:
1619876
Concept ID:
C4540192
Disease or Syndrome
NEMMLAS is an autosomal recessive multisystemic disorder characterized by delayed psychomotor development, intellectual disability, and abnormal motor function, including hypotonia, dystonia, ataxia, and spasticity. Patient tissues may show deficiencies in one or more of the mitochondrial oxidative phosphorylation (OXPHOS) enzymes, but this is not a constant finding (summary by Wortmann et al., 2017).
Alkaline ceramidase 3 deficiency
MedGen UID:
1622324
Concept ID:
C4540358
Disease or Syndrome
Neurodevelopmental disorder with severe motor impairment and absent language
MedGen UID:
1622162
Concept ID:
C4540496
Disease or Syndrome
NEDMIAL is a neurodevelopmental disorder characterized by severely delayed psychomotor development and hypotonia apparent from early infancy, resulting in feeding difficulties, ataxic gait or inability to walk, minimal or absent speech development, and severe intellectual disability, often with behavioral abnormalities, such as hand-flapping. Additional common features may include sleep disorder, nonspecific dysmorphic facial features, and joint hyperlaxity (summary by Lessel et al., 2017).
Neurodevelopmental disorder with ataxic gait, absent speech, and decreased cortical white matter
MedGen UID:
1621102
Concept ID:
C4540498
Disease or Syndrome
NDAGSCW is a neurodevelopmental disorder characterized by severely delayed psychomotor development apparent from infancy. Affected individuals have delayed and difficulty walking, intellectual disability, absent speech, and variable additional features, including hip dysplasia, tapering fingers, and seizures. Brain imaging shows decreased cortical white matter, often with decreased cerebellar white matter, thin corpus callosum, and thin brainstem (summary by Lamers et al., 2017).
Idiopathic basal ganglia calcification 1
MedGen UID:
1637664
Concept ID:
C4551624
Disease or Syndrome
Primary familial brain calcification (PFBC) is a neurodegenerative disorder with characteristic calcium deposits in the basal ganglia and other brain areas visualized on neuroimaging. Most affected individuals are in good health during childhood and young adulthood and typically present in the fourth to fifth decade with a gradually progressive movement disorder and neuropsychiatric symptoms. The movement disorder first manifests as clumsiness, fatigability, unsteady gait, slow or slurred speech, dysphagia, involuntary movements, or muscle cramping. Neuropsychiatric symptoms, often the first or most prominent manifestations, range from mild difficulty with concentration and memory to changes in personality and/or behavior, to psychosis and dementia. Seizures of various types occur frequently, some individuals experience chronic headache and vertigo; urinary urgency or incontinence may be present.
Galloway-Mowat syndrome 1
MedGen UID:
1634188
Concept ID:
C4551772
Disease or Syndrome
Inclusion body myopathy with early-onset Paget disease with or without frontotemporal dementia 1
MedGen UID:
1641069
Concept ID:
C4551951
Disease or Syndrome
Inclusion body myopathy associated with Paget disease of bone (PDB) and/or frontotemporal dementia (IBMPFD) is characterized by adult-onset proximal and distal muscle weakness (clinically resembling a limb-girdle muscular dystrophy syndrome), early-onset PDB, and premature frontotemporal dementia (FTD). Muscle weakness progresses to involve other limb and respiratory muscles. PDB involves focal areas of increased bone turnover that typically lead to spine and/or hip pain and localized enlargement and deformity of the long bones; pathologic fractures occur on occasion. Early stages of FTD are characterized by dysnomia, dyscalculia, comprehension deficits, and paraphasic errors, with minimal impairment of episodic memory; later stages are characterized by inability to speak, auditory comprehension deficits for even one-step commands, alexia, and agraphia. Mean age at diagnosis for muscle disease and PDB is 42 years; for FTD, 56 years. Dilated cardiomyopathy, amyotrophic lateral sclerosis, and Parkinson disease are now known to be part of the spectrum of findings associated with IBMPFD.
Cerebroretinal microangiopathy with calcifications and cysts 1
MedGen UID:
1636142
Concept ID:
C4552029
Disease or Syndrome
Cerebroretinal microangiopathy with calcifications and cysts (CRMCC), also known as Coats plus syndrome, is an autosomal recessive pleomorphic disorder characterized primarily by intracranial calcifications, leukodystrophy, and brain cysts, resulting in spasticity, ataxia, dystonia, seizures, and cognitive decline. Patients also have retinal telangiectasia and exudates (Coats disease) as well as extraneurologic manifestations, including osteopenia with poor bone healing and a high risk of gastrointestinal bleeding and portal hypertension caused by vasculature ectasias in the stomach, small intestine, and liver. Some individuals also have hair, skin, and nail changes, as well as anemia and thrombocytopenia (summary by Anderson et al., 2012 and Polvi et al., 2012). Leukoencephalopathy, brain calcifications, and cysts (LCC), also known as Labrune syndrome (614561), has similar central nervous system features as CRMCC in the absence of extraneurologic or systemic manifestations. Although Coats plus syndrome and Labrune syndrome were initially thought to be manifestations of the same disorder, namely CRMCC, molecular evidence has excluded mutations in the CTC1 gene in patients with Labrune syndrome, suggesting that the 2 disorders are not allelic (Anderson et al., 2012; Polvi et al., 2012). Some features of CRMCC resemble those observed in dyskeratosis congenita (see, e.g., 127550), which is a clinically and genetically heterogeneous telomere-related genetic disorder. Genetic Heterogeneity of Cerebroretinal Microangiopathy With Calcifications And Cysts See also CRMCC2 (617341), caused by mutation in the STN1 gene (613128) on chromosome 10q24.
Neurodevelopmental disorder with or without hyperkinetic movements and seizures, autosomal recessive
MedGen UID:
1646665
Concept ID:
C4693325
Disease or Syndrome
GRIN1-related neurodevelopmental disorder (GRIN1-NDD) is characterized by mild-to-profound developmental delay / intellectual disability (DD/ID) in all affected individuals. Other common manifestations are epilepsy, muscular hypotonia, movement disorders, spasticity, feeding difficulties, and behavior problems. A subset of individuals show a malformation of cortical development consisting of extensive and diffuse bilateral polymicrogyria. To date, 72 individuals with GRIN1-NDD have been reported.
Developmental and epileptic encephalopathy 92
MedGen UID:
1638319
Concept ID:
C4693362
Disease or Syndrome
Developmental and epileptic encephalopathy-92 (DEE92) is characterized in most patients by onset of seizures in infancy or childhood and associated with global developmental delay and variable impairment of intellectual development. The seizure type and severity varies, and seizures may be intractable in some patients. Some patients are severely affected, unable to walk or speak, whereas others show some development. Additional neurologic features, including cortical blindness, dystonia, and spasticity, may occur. Mutations occur de novo (summary by Hamdan et al., 2017). For a discussion of genetic heterogeneity of DEE, see 308350.
Developmental delay and seizures with or without movement abnormalities
MedGen UID:
1641343
Concept ID:
C4693376
Disease or Syndrome
DEDSM is a neurodevelopmental disorder characterized by global developmental delay, variable intellectual disability, and early-onset seizures with a myoclonic component. Most patients have delayed motor development and show abnormal movements, including ataxia, dystonia, and tremor (summary by Hamdan et al., 2017).
Combined oxidative phosphorylation deficiency 35
MedGen UID:
1639653
Concept ID:
C4693466
Disease or Syndrome
COXPD35 is an autosomal recessive disorder characterized mainly by global developmental delay with intellectual disability, microcephaly, and early-onset myoclonic and other types of seizures. Affected individuals have variable deficiencies of mitochondrial respiratory enzyme complexes resulting from a defect in mitochondrial metabolism (summary by Kernohan et al., 2017). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
Leukodystrophy, hypomyelinating, 14
MedGen UID:
1635255
Concept ID:
C4693535
Disease or Syndrome
Hypomyelinating leukodystrophy-14 is an autosomal recessive neurodevelopmental disorder characterized by hypotonia, almost complete lack of motor or cognitive skills, and absent language development. Additional features include spasticity and intractable seizures; many patients also have perceptive hearing loss and/or blindness. Most patients require tube feeding or ventilatory support, and most die in the first years of life. Brain imaging shows hypomyelination, small caudate and putamen, and cerebral and cerebellar atrophy (summary by Hamilton et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of hypomyelinating leukodystrophy, see 312080.
Neurodevelopmental disorder with poor language and loss of hand skills
MedGen UID:
1637031
Concept ID:
C4693546
Disease or Syndrome
NDPLHS is an autosomal dominant disorder characterized by developmental stagnation or regression apparent in the first years of life and manifest as loss of purposeful hand movements, loss of language, and intellectual disability. Additional features may include stereotypic movements, dystonia, gait abnormalities, sleep disturbances, and small hands and feet. The phenotype is reminiscent of Rett syndrome (RTT; 312750) (summary by Yoo et al., 2017).
Leukodystrophy, hypomyelinating, 15
MedGen UID:
1633653
Concept ID:
C4693733
Disease or Syndrome
Hypomyelinating leukodystrophy-15 is an autosomal recessive neurodegenerative disorder characterized by onset of motor and cognitive impairment in the first or second decade of life. Features include dystonia, ataxia, spasticity, and dysphagia. Most patients develop severe optic atrophy, and some have hearing loss. Brain imaging shows hypomyelinating leukodystrophy with thin corpus callosum. The severity of the disorder is variable (summary by Mendes et al., 2018) For a discussion of genetic heterogeneity of HLD, see 312080.
Multiple mitochondrial dysfunctions syndrome 6
MedGen UID:
1643082
Concept ID:
C4693741
Disease or Syndrome
Multiple mitochondrial dysfunctions syndrome-6 is an autosomal recessive severe neurodegenerative disorder with onset in early childhood. Affected individuals may have initial normal development, but show neurologic regression in the first year of life. They have hypotonia, inability to walk, poor speech, intellectual disability, and motor abnormalities, such as ataxia, dystonia, and spasticity. Some patients may die in childhood. Laboratory evidence indicates that the disorder results from mitochondrial dysfunction (summary by Vogtle et al., 2018). For a general description and a discussion of genetic heterogeneity of multiple mitochondrial dysfunctions syndrome, see MMDS1 (605711).
Leukodystrophy, hypomyelinating, 16
MedGen UID:
1631337
Concept ID:
C4693779
Disease or Syndrome
Hypomyelinating leukodystrophy-16 is an autosomal dominant neurologic disorder characterized by onset of hypotonia, nystagmus, and mildly delayed motor development in infancy. Affected individuals have motor disabilities, including ataxic or broad-based gait, hyperreflexia, intention tremor, dysmetria, and a mild pyramidal syndrome. Some patients have cognitive impairment, whereas others may have normal cognition or mild intellectual disability with speech difficulties. Brain imaging typically shows hypomyelination, leukodystrophy, and thin corpus callosum (summary by Simons et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of hypomyelinating leukodystrophy, see 312080.
Jaberi-Elahi syndrome
MedGen UID:
1647359
Concept ID:
C4693848
Disease or Syndrome
JABELS is an autosomal recessive neurodevelopmental disorder characterized by developmental delay and intellectual disability with additional variable features. Patients have onset of symptoms in infancy, but the severity is highly variable. Some patients have social interaction and learn to walk but have an ataxic gait and abnormal movements, such as tremor or dystonia, whereas others do not achieve any motor control and are unable to speak. Additional features may include retinal anomalies, visual impairment, microcephaly, abnormal foot or hand posturing, and kyphoscoliosis; some patients have dysmorphic facial features or seizures. Brain imaging typically shows cerebellar atrophy and hypoplasia of the corpus callosum (summary by et al., 2016 and Bertoli-Avella et al., 2018).
Developmental and epileptic encephalopathy, 64
MedGen UID:
1633501
Concept ID:
C4693899
Disease or Syndrome
Developmental and epileptic encephalopathy-64 (DEE64) is a neurodevelopmental disorder characterized by onset of seizures usually in the first year of life and associated with intellectual disability, poor motor development, and poor or absent speech. Additional features include hypotonia, abnormal movements, and nonspecific dysmorphic features. The severity is variable: some patients are unable to speak, walk, or interact with others as late as the teenage years, whereas others may have some comprehension (summary by Straub et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Parkinsonism-dystonia, infantile, 2
MedGen UID:
1648382
Concept ID:
C4747991
Disease or Syndrome
PKDYS2 is an autosomal recessive complex infantile-onset neurologic disorder characterized by abnormal movements, including parkinsonism, dystonia, and poor fine motor skills, as well as autonomic dysfunction, including abnormal sweating, cold extremities, and poor sleep. Some patients have variable degrees of developmental delay. Features of the disorder are consistent with decreased levels of monoamine neurotransmitters, although levels of these in the spinal fluid are normal. Preliminary findings indicate that treatment with a dopamine receptor agonist results in dramatic and sustained clinical improvement (summary by Rilstone et al., 2013). For a discussion of genetic heterogeneity of PKDYS, see 613135.
Spinocerebellar ataxia 42, early-onset, severe, with neurodevelopmental deficits
MedGen UID:
1648308
Concept ID:
C4748120
Disease or Syndrome
Neurodevelopmental disorder with regression, abnormal movements, loss of speech, and seizures
MedGen UID:
1648345
Concept ID:
C4748127
Disease or Syndrome
Congenital hypomyelinating neuropathy 3
MedGen UID:
1648417
Concept ID:
C4748608
Disease or Syndrome
Congenital hypomyelinating neuropathy-3 is an autosomal recessive neurologic disorder characterized by onset of neurogenic muscle impairment in utero. Affected individuals present at birth with severe hypotonia, often causing respiratory insufficiency or failure and inability to swallow or feed properly. They have profoundly impaired psychomotor development and may die in infancy or early childhood. Those that survive are unable to sit or walk. Sural nerve biopsy shows hypomyelination of the nerve fibers, and brain imaging often shows impaired myelination and cerebral and cerebellar atrophy. Nerve conduction velocities are severely decreased (about 10 m/s) or absent due to improper myelination (summary by Vallat et al., 2016 and Low et al., 2018). For a discussion of genetic heterogeneity of CHN, see CHN1 (605253).
Infantile hypotonia-oculomotor anomalies-hyperkinetic movements-developmental delay syndrome
MedGen UID:
1648431
Concept ID:
C4748715
Disease or Syndrome
Baker-Gordon syndrome (BAGOS) is a neurodevelopmental disorder characterized by infantile hypotonia, ophthalmic abnormalities, moderate to profound global developmental delay, poor or absent speech, behavioral abnormalities, hyperkinetic movements, and EEG abnormalities in the absence of overt seizures (summary by Baker et al., 2018).
Mitochondrial complex 1 deficiency, nuclear type 2
MedGen UID:
1648466
Concept ID:
C4748737
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 3
MedGen UID:
1648346
Concept ID:
C4748752
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 5
MedGen UID:
1648292
Concept ID:
C4748754
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 8
MedGen UID:
1648411
Concept ID:
C4748766
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 15
MedGen UID:
1648320
Concept ID:
C4748778
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 16
MedGen UID:
1648351
Concept ID:
C4748785
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 17
MedGen UID:
1648418
Concept ID:
C4748786
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 23
MedGen UID:
1648408
Concept ID:
C4748799
Disease or Syndrome
Mitochondrial complex 1 deficiency, nuclear type 26
MedGen UID:
1648283
Concept ID:
C4748809
Disease or Syndrome
Neurodegeneration, childhood-onset, with cerebellar atrophy
MedGen UID:
1648286
Concept ID:
C4748934
Disease or Syndrome
Childhood-onset neurodegeneration with cerebellar atrophy is a severe autosomal recessive neurodevelopmental disorder affecting the central and peripheral nervous system. Patients present in the first year of life with global developmental delay, impaired intellectual development, poor or absent speech, and motor abnormalities. Brain imaging shows cerebellar atrophy. The severity is variable, but death in childhood may occur (summary by Shashi et al., 2018).
Fibrosis, neurodegeneration, and cerebral angiomatosis
MedGen UID:
1648312
Concept ID:
C4748939
Disease or Syndrome
Fibrosis, neurodegeneration, and cerebral angiomatosis is characterized by severe progressive cerebropulmonary symptoms, resulting in death in infancy from respiratory failure. Features include malabsorption, progressive growth failure, recurrent infections, chronic hemolytic anemia, and transient liver dysfunction. Neuropathology shows increased angiomatosis-like leptomeningeal, cortical, and superficial white matter vascularization and congestion, vacuolar degeneration and myelin loss in white matter, as well as neuronal degeneration. Interstitial fibrosis and granuloma-like lesions are seen in the lungs, and there is hepatomegaly with steatosis and collagen accumulation (Uusimaa et al., 2018).
Developmental and epileptic encephalopathy, 69
MedGen UID:
1648381
Concept ID:
C4748988
Disease or Syndrome
Developmental and epileptic encephalopathy-69 (DEE69) is an autosomal dominant severe neurodevelopmental encephalopathic disorder characterized by early-onset refractory seizures, hypotonia, and profoundly impaired development often associated with macrocephaly, hyperkinetic movements, and contractures. The disorder can sometimes result in early death. Some patients may have a favorable seizure response to topiramate medication (summary by Helbig et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of DEE, see 308350.
Lethal arthrogryposis with anterior horn cell disease
MedGen UID:
1677784
Concept ID:
C5193016
Disease or Syndrome
Congenital arthrogryposis with anterior horn cell disease (CAAHD) is an autosomal recessive neuromuscular disorder with highly variable severity. Affected individuals are usually noted to have contractures in utero on prenatal ultrasound studies, and present at birth with generalized contractures manifest as arthrogryposis multiplex congenita (AMC). Patients have severe hypotonia with respiratory insufficiency, often resulting in death in infancy or early childhood. Some patients may survive into later childhood with supportive care, but may be unable to walk or sit independently due to a combination of muscle weakness and contractures. Cognition may be normal. The disorder also includes multiple congenital anomalies associated with AMC and hypotonia, including high-arched palate, myopathic facies, and bulbar weakness. Neuropathologic studies demonstrate severe loss of anterior horn cells in the spinal cord, as well as diffuse motor neuron axonopathy (summary by Smith et al., 2017 and Tan et al., 2017). Distinction from Lethal Congenital Contracture Syndrome 1 Biallelic mutation in the GLE1 gene can also cause LCCS1, which is lethal in utero. However, distinguishing between LCCS1 and CAAHD is controversial. Smith et al. (2017) suggested that differentiating between the 2 disorders has limited utility, and that they may represent a genotype/phenotype correlation rather than 2 different disease entities. In contrast, Said et al. (2017) concluded that LCCS1 represents a distinct clinical entity in which all affected individuals die prenatally and exhibit no fetal movements. Vuopala et al. (1995) differentiated CAAHD from LCCS1, noting that both are prevalent in Finland. LCCS1 is always fatal during the fetal period, presenting with severe hydrops and intrauterine growth retardation. In LCCS1, the spinal cord is macroscopically thinned because of an early reduction of the anterior horn and a paucity of anterior horn cells. The skeletal muscles are extremely hypoplastic, even difficult to locate. Infants with CAAHD survive longer than those with LCCS1, and when present, hydrops and intrauterine growth retardation are mild. The macroscopic findings of the central nervous system and skeletal muscles are closer to normal, although microscopic analysis also shows degeneration of anterior horn cells. In addition, birthplaces of ancestors of affected individuals do not show clustering in the northeast part of Finland, as is the case with LCCS1.
Basal ganglia calcification, idiopathic, 7, autosomal recessive
MedGen UID:
1683911
Concept ID:
C5193025
Disease or Syndrome
Autosomal recessive idiopathic basal ganglia calcification-7 is a neurologic disorder characterized by onset of symptoms in adulthood. Patients present with dysarthria, gait abnormalities, various movement abnormalities, and often cognitive decline. Brain imaging shows abnormal accumulation of calcium deposits in deep brain regions, including the basal ganglia, thalamus, dentate nuclei, cerebellum, and sometimes other areas of the brain and spinal cord. Some patients with brain imaging abnormalities may be clinically asymptomatic (summary by Yao et al., 2018). For a detailed phenotypic description and a discussion of genetic heterogeneity of IBGC, see IBGC1 (213600).
Encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy, 2
MedGen UID:
1681210
Concept ID:
C5193026
Disease or Syndrome
Early-onset progressive encephalopathy with brain edema and/or leukoencephalopathy-2 (PEBEL2) is an autosomal recessive severe neurometabolic disorder characterized by rapidly progressive neurologic deterioration that is usually associated with a febrile illness. Affected infants tend to show normal early development followed by acute psychomotor regression with ataxia, hypotonia, and sometimes seizures, resulting in death in the first years of life. Brain imaging shows multiple abnormalities, including brain edema and signal abnormalities in the cortical and subcortical regions (summary by Van Bergen et al., 2019). For a discussion of genetic heterogeneity of PEBEL, see PEBEL1 (617186).
Combined oxidative phosphorylation deficiency 39
MedGen UID:
1683958
Concept ID:
C5193075
Disease or Syndrome
Combined oxidative phosphorylation deficiency-39 (COXPD39) is an autosomal recessive multisystem disorder resulting from a defect in mitochondrial energy metabolism. Affected individuals show global developmental delay, sometimes with regression after normal early development, axial hypotonia with limb spasticity or abnormal involuntary movements, and impaired intellectual development with poor speech. More variable features may include hypotonia, seizures, and features of Leigh syndrome (256000) on brain imaging. There are variable deficiencies of the mitochondrial respiratory chain enzyme complexes in patient tissues (summary by Glasgow et al., 2017). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060).
Leukodystrophy, hypomyelinating, 18
MedGen UID:
1680067
Concept ID:
C5193078
Disease or Syndrome
Hypomyelinating leukodystrophy-18 (HLD18) is an autosomal recessive neurologic disorder characterized by onset of global developmental delay usually in early infancy. Affected individuals have very poor psychomotor development, including inability to sit or walk independently in the more severe cases, as well as poor or absent speech, dystonia, and spasticity. A subset of patients may develop seizures. Brain imaging shows hypomyelinating leukodystrophy affecting various brain regions; some patients may also have progressive atrophy of the corpus callosum, thalami, and cerebellum (summary by Pant et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of hypomyelinating leukodystrophy, see 312080.
Metabolic crises, recurrent, with variable encephalomyopathic features and neurologic regression
MedGen UID:
1681269
Concept ID:
C5193083
Disease or Syndrome
Recurrent metabolic crises with variable encephalomyopathic features and neurologic regression (MECREN) is an autosomal recessive metabolic disorder with a highly variable phenotype. Most affected individuals present in the first years of life with episodic lactic acidosis associated with illness or stress, resulting in transient or permanent neurologic dysfunction. Some patients may recover, whereas others show subsequent variable developmental regression of motor and cognitive skills. Other features may include dystonia, hypotonia with inability to sit or walk, seizures, and abnormal signals in the basal ganglia. There is significant phenotypic heterogeneity, even among patients with the same mutation (summary by Almannai et al., 2018).
Neurodevelopmental disorder with impaired speech and hyperkinetic movements
MedGen UID:
1681181
Concept ID:
C5193088
Disease or Syndrome
Neurodevelopmental disorder with impaired speech and hyperkinetic movements (NEDISHM) is an autosomal recessive disorder characterized by global developmental delay apparent in infancy. Most patients have mildly delayed walking, speech and language delay, and a hyperkinetic movement disorder with dystonia, tremor, ataxia, or chorea. Some may develop seizures that tend to abate (summary by Khan et al., 2019).
Neurodegeneration, early-onset, with choreoathetoid movements and microcytic anemia
MedGen UID:
1676579
Concept ID:
C5193104
Disease or Syndrome
Early-onset neurodegeneration with choreoathetoid movements and microcytic anemia (NDCAMA) is an autosomal recessive disorder characterized by severe psychomotor developmental abnormalities, abnormal movements, and functional iron deficiency (Costain et al., 2019).
Neurodevelopmental disorder with seizures and nonepileptic hyperkinetic movements
MedGen UID:
1678038
Concept ID:
C5193128
Disease or Syndrome
Neurodevelopmental disorder with seizures and nonepileptic hyperkinetic movements (NEDNEH) is an autosomal recessive severe neurologic disorder characterized by delayed psychomotor development with inability to walk or speak, early-onset refractory seizures, and nonepileptic hyperkinetic movement disorders, including myoclonus dystonia and dyskinesias. Patients require tube feeding and may die of respiratory failure in childhood or in the second decade (summary by Gorman et al., 2019).
Diencephalic-mesencephalic junction dysplasia syndrome 2
MedGen UID:
1684846
Concept ID:
C5231440
Disease or Syndrome
Diencephalic-mesencephalic junction dysplasia syndrome-2 (DMJDS2) is an autosomal recessive neurodevelopmental disorder characterized by global developmental delay and hypotonia apparent from infancy. Affected individuals develop severe progressive hyperkinetic movements, including spastic tetraplegia, dystonia, and bulbar dysphagia necessitating tube feeding. Patients are unable to walk and have severely impaired intellectual development with absent speech. Brain imaging shows a unique malformation reflecting abnormal embryonic development of the diencephalic-mesencephalic junction (DMJ), with agenesis of the basal ganglia and olfactory bulb, hypoplasia of the thalamus, and abnormal course of the corticospinal tracts (summary by De Mori et al., 2019). For a discussion of genetic heterogeneity of DMJDS, see DMJDS1 (251280).
Liang-Wang syndrome
MedGen UID:
1684847
Concept ID:
C5231479
Disease or Syndrome
Liang-Wang syndrome (LIWAS) is a polymalformation syndrome apparent from birth that shows large phenotypic variability and severity. However, all patients have some degree of neurologic dysfunction. The most severely affected individuals have severe global developmental delay with impaired intellectual development and poor or absent speech, marked craniofacial dysmorphism, and visceral and connective tissue abnormalities affecting the bones and vessels. The least severely affected individuals lack seizures, significant dysmorphism, and visceral involvement; they come to attention for neurologic signs and symptoms, including developmental delay with speech delay, strabismus, and/or ataxia. About half of patients have brain imaging anomalies, notably cerebral and cerebellar atrophy and thin corpus callosum, whereas the other half have normal brain imaging (summary by Liang et al., 2019).
Neurodevelopmental disorder with hypotonia and autistic features with or without hyperkinetic movements
MedGen UID:
1684874
Concept ID:
C5231491
Disease or Syndrome
Neurodevelopmental disorder with hypotonia and autistic features with or without hyperkinetic movements (NEDHAHM) is characterized by axial hypotonia apparent from birth, global developmental delay with impaired intellectual development and poor or absent language acquisition, and behavioral abnormalities, including autistic features, poor social interaction, and hang-wringing. Most patients have childhood-onset seizures that are usually responsive to medication, and a subset of patients develop cortical visual impairment and involuntary hyperkinetic movements, including chorea and dystonia. Some of the features are reminiscent of Rett syndrome (RTT; 312750) (summary by Salpietro et al., 2019).
Developmental and epileptic encephalopathy, 84
MedGen UID:
1720141
Concept ID:
C5394081
Disease or Syndrome
Developmental and epileptic encephalopathy-84 (DEE84) is an autosomal recessive neurologic disorder characterized by onset of refractory seizures in the first months or years of life. Affected individuals have severely impaired global development with impaired intellectual development, absent speech, and inability to walk. Other features include axial hypotonia, peripheral spasticity, feeding difficulties that sometimes necessitate tube feeding, and mild dysmorphic facial features. Brain imaging may show nonspecific findings such as cerebral/cerebellar atrophy and/or hypomyelination. The severity of the disorder is variable (summary by Hengel et al., 2020). For a discussion of genetic heterogeneity of DEE, see 308350.
Neurodevelopmental disorder with relative macrocephaly and with or without cardiac or endocrine anomalies
MedGen UID:
1714169
Concept ID:
C5394221
Disease or Syndrome
Nabais Sa-de Vries syndrome type 2 (NSDVS2) is characterized by global developmental delay apparent from birth and distinctive dysmorphic facial features. Most patients have additional anomalies, including congenital heart defects, sleep disturbances, hypotonia, and variable endocrine abnormalities, such as hypothyroidism (summary by Nabais Sa et al., 2020).
Neurodegeneration, childhood-onset, with ataxia, tremor, optic atrophy, and cognitive decline
MedGen UID:
1715031
Concept ID:
C5394335
Disease or Syndrome
Childhood-onset neurodegeneration with ataxia, tremor, optic atrophy, and cognitive decline (CONATOC) is an autosomal recessive progressive disorder with onset of symptoms in the first decade. Brain imaging may show variable features, including leukoencephalopathy and cerebellar atrophy (summary by Fagerberg et al., 2020).
Leukoencephalopathy, developmental delay, and episodic neurologic regression syndrome
MedGen UID:
1719567
Concept ID:
C5394367
Disease or Syndrome
Leukoencephalopathy, developmental delay, and episodic neurologic regression syndrome (LEUDEN) is characterized by global developmental delay apparent in early childhood, followed by episodic neurologic regression or decompensation associated with systemic stress, such as febrile infection. Affected individuals have hypotonia, gait difficulties or ataxia, poor or absent speech with dysarthria, and variable motor abnormalities, including spasticity, dystonia, extrapyramidal signs, and tremor. Many patients have seizures. Brain imaging shows diffuse white matter abnormalities, poor myelination, thin corpus callosum, and generalized cerebral atrophy with enlarged ventricles. The clinical features of the disorder and the abnormal brain imaging findings are progressive (summary by Mao et al., 2020).
Microcephaly, developmental delay, and brittle hair syndrome
MedGen UID:
1718781
Concept ID:
C5394425
Disease or Syndrome
Microcephaly, developmental delay, and brittle hair syndrome (MDBH) is a multisystem disorder with clinical variability. Affected individuals show cognitive and motor disabilities, as well as some degree of fine, brittle hair with microscopic shaft abnormalities. Other shared features include failure to thrive in early childhood and short stature, with some patients exhibiting feeding difficulties and hepatic steatosis (Kuo et al., 2019).
Developmental and epileptic encephalopathy, 86
MedGen UID:
1711964
Concept ID:
C5394462
Disease or Syndrome
Neurodevelopmental disorder with language impairment and behavioral abnormalities
MedGen UID:
1708389
Concept ID:
C5394502
Disease or Syndrome
Neurodevelopmental disorder with speech impairment and behavioral abnormalities (NEDLIB) is characterized by impaired intellectual development or developmental delay, behavioral abnormalities including autistic features, and language impairment. Other features include seizures and developmental regression (Salpietro et al., 2019).
Episodic ataxia type 9
MedGen UID:
1714171
Concept ID:
C5394520
Disease or Syndrome
Episodic ataxia type 9 (EA9) is a neurologic disorder characterized by onset of ataxic episodes in the first years of life. Features may include difficulty walking, dizziness, slurred speech, headache, vomiting, and pain. The ataxic episodes vary in frequency and duration; most tend to occur every few weeks or months and last minutes to hours. Prior to the EA, most patients have neonatal- or infantile-onset tonic or generalized tonic-clonic (GTC) seizures that may be severe and refractory to medication, but remit later in infancy or early childhood, either spontaneously or concurrently with medication. Some patients have mildly delayed development with speech delay and/or autistic features or mildly impaired intellectual development. However, others show normal psychomotor development. Treatment of the ataxic episodes with acetazolamide is effective in about 50% of patients (summary by Schwarz et al., 2019). For a phenotypic description and discussion of genetic heterogeneity of episodic ataxia, see EA1 (160120).
Joubert syndrome with hepatic defect
MedGen UID:
1769861
Concept ID:
C5435651
Disease or Syndrome
COACH syndrome is an autosomal recessive disorder characterized by impaired intellectual development, ataxia due to cerebellar hypoplasia, and hepatic fibrosis. Other features, such as coloboma and renal cysts, may be variable. COACH syndrome is considered by some to be a subtype of Joubert syndrome (JBTS; see 213300) with congenital hepatic fibrosis. Identification of liver disease in these patients is critical because some may develop complications such as portal hypertension with fatal variceal bleeding (Brancati et al., 2009; Doherty et al., 2010). Genetic Heterogeneity of COACH Syndrome Also see COACH syndrome-2 (COACH2; 619111), caused by mutation in in the CC2D2A gene (612013), and COACH syndrome-3 (COACH3; 619113), caused by mutation the RPGRIP1L gene (610937). Most cases of COACH syndrome are caused by mutation in the TMEM67 gene.
Arthrogryposis multiplex congenita 5
MedGen UID:
1731112
Concept ID:
C5436453
Disease or Syndrome
Arthrogryposis multiplex congenita-5 (AMC5) is an autosomal recessive disorder characterized by severe joint contractures apparent at birth. Affected individuals usually have hypertonia and abnormal movements suggestive of dystonia, as well as feeding and/or breathing difficulties. More variable features may include poor overall growth, strabismus, dysmorphic facies, and global developmental delay with impaired speech (summary by Kariminejad et al., 2017).
Mitochondrial complex 4 deficiency, nuclear type 21
MedGen UID:
1732562
Concept ID:
C5436727
Disease or Syndrome
Mitochondrial complex IV deficiency nuclear type 21 (MC4DN21) is an autosomal recessive multisystem metabolic disorder characterized by the onset of symptoms in infancy. Affected individuals present with congenital lactic acidosis and later show global developmental delay with delayed speech and learning disabilities. Additional features include motor dysfunction manifest as spasticity, dystonia, and pyramidal tract signs. Ataxia, peripheral neuropathy, and seizures may also occur. Brain imaging shows T2-weighted hyperintensities in subcortical regions, consistent with a clinical diagnosis of Leigh syndrome (see 256000). Patient tissues show variably decreased levels and activity of mitochondrial respiratory complex IV (Pitceathly et al., 2013). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110.
Leukodystrophy, hypomyelinating, 20
MedGen UID:
1765130
Concept ID:
C5436730
Disease or Syndrome
Hypomyelinating leukodystrophy-20 (HLD20) is an autosomal recessive neurodegenerative disorder characterized by the loss of developmental milestones at about 12 to 16 months of age after normal early development. Patients lose motor, language, and cognitive skills and show poor overall growth with microcephaly. The disorder is progressive, resulting in feeding difficulties and spastic quadriplegia. Some patients may have seizures. Brain imaging shows subcortical white matter abnormalities and a thin corpus callosum, suggesting a myelination defect. Death usually occurs in childhood (Al-Abdi et al., 2020). For a discussion of genetic heterogeneity of HLD, see 312080.
Developmental and epileptic encephalopathy 89
MedGen UID:
1761611
Concept ID:
C5436853
Disease or Syndrome
Developmental and epileptic encephalopathy-89 (DEE89) is a severe autosomal recessive disorder characterized by profound global developmental delay with impaired intellectual development, absent speech, inability to sit or walk due to axial hypotonia and spastic quadriparesis, and onset of seizures in the first days or months of life. EEG shows suppression-burst pattern or hypsarrhythmia, consistent with DEE or a clinical diagnosis of West syndrome. More variable features include joint contractures with foot deformities, dysmorphic facial features with cleft palate, and omphalocele. Affected individuals have poor motor skills, poor eye contact, and lack of language development; some die in infancy or early childhood. Brain imaging may be normal or show nonspecific abnormalities (summary by Chatron et al., 2020).
Intellectual developmental disorder with paroxysmal dyskinesia or seizures
MedGen UID:
1727046
Concept ID:
C5436894
Disease or Syndrome
Intellectual developmental disorder with paroxysmal dyskinesia or seizures (IDDPADS) is an autosomal recessive complex neurologic disorder characterized by global developmental delay with impaired intellectual development and language delay. In addition, most patients develop a paroxysmal hyperkinetic movement disorder in the first months or years of life manifest as sudden falls or backward propulsion, eye or head deviation, and dystonic limb posturing followed by chorea and dyskinetic movements. The episodes are pharmacoresistant to anticonvulsant medication. EEG may show interictal abnormalities, but are usually not consistent with epilepsy. However, some patients may also develop epileptic seizures or only have seizures without a movement disorder (summary by Doummar et al., 2020).
Neurodevelopmental disorder with or without early-onset generalized epilepsy
MedGen UID:
1737097
Concept ID:
C5436914
Disease or Syndrome
Neurodevelopmental disorder with or without early-onset generalized epilepsy (NEDEGE) is characterized by global developmental delay apparent from infancy or early childhood. Affected individuals have variably impaired intellectual development, speech delay, and behavioral abnormalities. About half of patients develop early-onset generalized epilepsy with different seizure types; myoclonic seizures and myoclonic-atonic epilepsy are commonly observed. The seizures may remit with age or remain refractory to treatment. Brain imaging is essentially normal and there are no significant accompanying neurologic or systemic abnormalities (summary by Mulhern et al., 2018).
Mitochondrial complex 2 deficiency, nuclear type 3
MedGen UID:
1751884
Concept ID:
C5436934
Disease or Syndrome
Mitochondrial complex II deficiency nuclear type 3 (MC2DN3) is an autosomal recessive multisystemic metabolic disorder with a highly variable phenotype. Some patients may have an encephalomyopathic picture with episodic developmental regression, loss of motor skills, hypotonia, ataxia, dystonia, and seizures or myoclonus. Other patients present in infancy with hypertrophic cardiomyopathy, which may be fatal. Laboratory studies show increased serum lactate and mitochondrial complex II deficiency in muscle and fibroblasts (summary by Jackson et al., 2014 and Alston et al., 2015). For a discussion of genetic heterogeneity of MC2DN, see MC2DN1 (252011).
Maple syrup urine disease, type 3
MedGen UID:
449386
Concept ID:
CN043137
Disease or Syndrome
The phenotypes of dihydrolipoamide dehydrogenase (DLD) deficiency are an overlapping continuum that ranges from early-onset neurologic manifestations to adult-onset liver involvement and, rarely, a myopathic presentation. Early-onset DLD deficiency typically manifests in infancy as hypotonia with lactic acidosis. Affected infants frequently do not survive their initial metabolic decompensation, or die within the first few years of life during a recurrent metabolic decompensation. Children who live beyond the first two to three years frequently exhibit growth deficiencies and residual neurologic deficits (intellectual disability, spasticity, ataxia, and seizures). In contrast, isolated liver involvement can present as early as the neonatal period and as late as the third decade. Evidence of liver injury/failure is preceded by nausea and emesis and frequently associated with encephalopathy and/or coagulopathy. Acute metabolic episodes are frequently associated with lactate elevations, hyperammonemia, and hepatomegaly. With resolution of the acute episodes affected individuals frequently return to baseline with no residual neurologic deficit or intellectual disability. Liver failure can result in death, even in those with late-onset disease. Individuals with the myopathic presentation may experience muscle cramps, weakness, and an elevated creatine kinase.
Myoclonus, familial, 2
MedGen UID:
1683864
Concept ID:
C5193056
Disease or Syndrome
Familial myoclonus-2 is an autosomal dominant neurologic condition characterized by childhood onset of isolated action-induced nonepileptic myoclonus affecting the upper limbs. The disorder is nonprogressive (Wagnon et al., 2018).

Recent clinical studies

Etiology

Gray J, Welck M, Cullen NP, Singh D
Bone Joint J 2021 Jun;103-B(6):1127-1132. doi: 10.1302/0301-620X.103B6.BJJ-2020-2187.R2. PMID: 34058886
Papadimitriou I, Dalivigka Z, Outsika C, Scarmeas N, Pons R
Eur J Paediatr Neurol 2021 May;32:8-15. Epub 2021 Mar 11 doi: 10.1016/j.ejpn.2021.03.005. PMID: 33743389
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Eur J Neurol 2021 Apr;28(4):1188-1197. Epub 2020 Dec 6 doi: 10.1111/ene.14638. PMID: 33175450
Morgan A, Eccles FJR, Greasley P
Disabil Rehabil 2021 Apr;43(7):944-952. Epub 2019 Aug 2 doi: 10.1080/09638288.2019.1645217. PMID: 31370703
Defazio G, Ercoli T, Erro R, Pellicciari R, Mascia MM, Fabbrini G, Albanese A, Lalli S, Eleopra R, Barone P, Marchese R, Ceravolo R, Scaglione C, Liguori R, Esposito M, Bentivoglio AR, Bertolasi L, Altavista MC, Bono F, Pisani A, Girlanda P, Berardelli A; Italian Dystonia Registry Participants.
Mov Disord 2020 Nov;35(11):2038-2045. Epub 2020 Jul 14 doi: 10.1002/mds.28199. PMID: 32662572

Diagnosis

Gray J, Welck M, Cullen NP, Singh D
Bone Joint J 2021 Jun;103-B(6):1127-1132. doi: 10.1302/0301-620X.103B6.BJJ-2020-2187.R2. PMID: 34058886
Simonyan K, Barkmeier-Kraemer J, Blitzer A, Hallett M, Houde JF, Jacobson Kimberley T, Ozelius LJ, Pitman MJ, Richardson RM, Sharma N, Tanner K; The NIH/NIDCD Workshop on Research Priorities in Spasmodic Dysphonia/Laryngeal Dystonia.
Neurology 2021 May 25;96(21):989-1001. Epub 2021 Apr 15 doi: 10.1212/WNL.0000000000011922. PMID: 33858994Free PMC Article
Ferlazzo E, Ascoli M, Abate F, Gasparini S, Mastroianni G, Cianci V, Ferrigno G, Sueri C, D'Agostino T, Aguglia U
J Neurol 2021 Jun;268(6):2208-2212. Epub 2021 Jan 23 doi: 10.1007/s00415-020-10395-4. PMID: 33484323
Morgan A, Eccles FJR, Greasley P
Disabil Rehabil 2021 Apr;43(7):944-952. Epub 2019 Aug 2 doi: 10.1080/09638288.2019.1645217. PMID: 31370703
Kim M, Kim AR, Park J, Kim JS, Ahn JH, Park WY, Kim NKD, Lee C, Kim NS, Cho JW, Youn J
Clin Neurol Neurosurg 2020 Dec;199:106267. Epub 2020 Oct 3 doi: 10.1016/j.clineuro.2020.106267. PMID: 33080427

Therapy

Thongchuam Y, Panyakaew P, Bhidayasiri R
J Neurol Sci 2020 Oct 15;417:116992. Epub 2020 Jun 19 doi: 10.1016/j.jns.2020.116992. PMID: 32622521
Fearon C, Peall KJ, Vidailhet M, Fasano A
Parkinsonism Relat Disord 2020 Aug;77:48-56. Epub 2020 Jun 23 doi: 10.1016/j.parkreldis.2020.06.016. PMID: 32622300
Spiegel LL, Ostrem JL, Bledsoe IO
Toxins (Basel) 2020 May 17;12(5) doi: 10.3390/toxins12050332. PMID: 32429600Free PMC Article
Murgai AA, Jog M
Toxicon 2020 Mar;176:10-14. Epub 2020 Jan 13 doi: 10.1016/j.toxicon.2020.01.004. PMID: 31965968
Shetty AS, Bhatia KP, Lang AE
Neurobiol Dis 2019 Dec;132:104462. Epub 2019 May 9 doi: 10.1016/j.nbd.2019.05.001. PMID: 31078682

Prognosis

Gray J, Welck M, Cullen NP, Singh D
Bone Joint J 2021 Jun;103-B(6):1127-1132. doi: 10.1302/0301-620X.103B6.BJJ-2020-2187.R2. PMID: 34058886
Zech M, Jech R, Boesch S, Škorvánek M, Necpál J, Švantnerová J, Wagner M, Sadr-Nabavi A, Distelmaier F, Krenn M, Serranová T, Rektorová I, Havránková P, Mosejová A, Příhodová I, Šarláková J, Kulcsarová K, Ulmanová O, Bechyně K, Ostrozovičová M, Haň V, Ventosa JR, Brunet T, Berutti R, Shariati M, Shoeibi A, Schneider SA, Kuster A, Baumann M, Weise D, Wilbert F, Janzarik WG, Eckenweiler M, Mall V, Haslinger B, Berweck S, Winkelmann J, Oexle K
Mov Disord 2021 Aug;36(8):1959-1964. Epub 2021 May 5 doi: 10.1002/mds.28614. PMID: 33949708
Wang JJ, Tian H, Rao J, Xiong N, Yi DY, Liu XM, Xiang W, Zhao HY, Jiang XB, Fu P
Neurol Sci 2021 Jul;42(7):2661-2671. Epub 2021 Apr 14 doi: 10.1007/s10072-021-05214-1. PMID: 33855621
Macerollo A, Sajin V, Bonello M, Barghava D, Alusi SH, Eldridge PR, Osman-Farah J
J Neurosci Methods 2020 Jul 1;340:108750. Epub 2020 Apr 25 doi: 10.1016/j.jneumeth.2020.108750. PMID: 32344043
Boyce MJ, Chang FCF, Mahant N, Fung VSC, Bradnam L
Physiother Res Int 2020 Jul;25(3):e1840. Epub 2020 Apr 8 doi: 10.1002/pri.1840. PMID: 32267046

Clinical prediction guides

Zech M, Jech R, Boesch S, Škorvánek M, Necpál J, Švantnerová J, Wagner M, Sadr-Nabavi A, Distelmaier F, Krenn M, Serranová T, Rektorová I, Havránková P, Mosejová A, Příhodová I, Šarláková J, Kulcsarová K, Ulmanová O, Bechyně K, Ostrozovičová M, Haň V, Ventosa JR, Brunet T, Berutti R, Shariati M, Shoeibi A, Schneider SA, Kuster A, Baumann M, Weise D, Wilbert F, Janzarik WG, Eckenweiler M, Mall V, Haslinger B, Berweck S, Winkelmann J, Oexle K
Mov Disord 2021 Aug;36(8):1959-1964. Epub 2021 May 5 doi: 10.1002/mds.28614. PMID: 33949708
Centen LM, Oterdoom DLM, Tijssen MAJ, Lesman-Leegte I, van Egmond ME, van Dijk JMC
Mov Disord 2021 Mar;36(3):547-557. Epub 2020 Nov 20 doi: 10.1002/mds.28384. PMID: 33215750Free PMC Article
Saryyeva A, Capelle HH, Kinfe TM, Schrader C, Krauss JK
Stereotact Funct Neurosurg 2021;99(1):1-5. Epub 2020 Oct 20 doi: 10.1159/000509822. PMID: 33080617
Andelman-Gur MM, Leventer RJ, Hujirat M, Ganos C, Yosovich K, Carmi N, Lev D, Nissenkorn A, Dobyns WB, Bhatia K, Lerman-Sagie T, Blumkin L
Am J Med Genet A 2020 Oct;182(10):2207-2213. Epub 2020 Aug 17 doi: 10.1002/ajmg.a.61795. PMID: 33001581
Li XY, Dai LF, Wan XH, Guo Y, Dai Y, Li SL, Fang F, Wang XH, Zhang WH, Liu TH, Xie ZH, Fang T, Wang L, Ding CH
Parkinsonism Relat Disord 2020 Aug;77:76-82. Epub 2020 Jun 9 doi: 10.1016/j.parkreldis.2020.06.002. PMID: 32634684

Recent systematic reviews

Przytuła F, Dulski J, Sobstyl M, Sławek J
Neurol Neurochir Pol 2021;55(4):346-350. Epub 2021 May 31 doi: 10.5603/PJNNS.a2021.0041. PMID: 34056704
Lange LM, Junker J, Loens S, Baumann H, Olschewski L, Schaake S, Madoev H, Petkovic S, Kuhnke N, Kasten M, Westenberger A, Domingo A, Marras C, König IR, Camargos S, Ozelius LJ, Klein C, Lohmann K
Mov Disord 2021 May;36(5):1086-1103. Epub 2021 Jan 27 doi: 10.1002/mds.28485. PMID: 33502045
Centen LM, Oterdoom DLM, Tijssen MAJ, Lesman-Leegte I, van Egmond ME, van Dijk JMC
Mov Disord 2021 Mar;36(3):547-557. Epub 2020 Nov 20 doi: 10.1002/mds.28384. PMID: 33215750Free PMC Article
Gómez-Garre P, Jesús S, Periñán MT, Adarmes A, Alonso-Canovas A, Blanco-Ollero A, Buiza-Rueda D, Carrillo F, Catalán-Alonso MJ, Del Val J, Escamilla-Sevilla F, Espinosa-Rosso R, Fernández-Moreno MC, García-Moreno JM, García-Ruiz PJ, Giacometti-Silveira S, Gutiérrez-García J, López-Valdés E, Macías-García D, Martínez-Castrillo JC, Martínez-Torres I, Medialdea-Natera MP, Mínguez-Castellanos A, Moya MÁ, Ochoa-Sepulveda JJ, Ojea T, Rodríguez N, Sillero-Sánchez M, Tejera-Parrado C, Mir P
Eur J Neurol 2021 Apr;28(4):1188-1197. Epub 2020 Dec 6 doi: 10.1111/ene.14638. PMID: 33175450
Hale AT, Monsour MA, Rolston JD, Naftel RP, Englot DJ
Neurosurg Rev 2020 Jun;43(3):873-880. Epub 2018 Nov 5 doi: 10.1007/s10143-018-1047-9. PMID: 30397842Free PMC Article

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