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Results: 1 to 20 of 665

1.

Biotinidase deficiency

If untreated, young children with profound biotinidase deficiency usually exhibit neurologic abnormalities including seizures, hypotonia, ataxia, developmental delay, vision problems, hearing loss, and cutaneous abnormalities (e.g., alopecia, skin rash, candidiasis). Older children and adolescents with profound biotinidase deficiency often exhibit motor limb weakness, spastic paresis, and decreased visual acuity. Once vision problems, hearing loss, and developmental delay occur, they are usually irreversible, even with biotin therapy. Individuals with partial biotinidase deficiency may have hypotonia, skin rash, and hair loss, particularly during times of stress. [from GeneReviews]

MedGen UID:
66323
Concept ID:
C0220754
Congenital Abnormality
2.

Leigh's disease

Leigh syndrome is an early-onset progressive neurodegenerative disorder with a characteristic neuropathology consisting of focal, bilateral lesions in one or more areas of the central nervous system, including the brainstem, thalamus, basal ganglia, cerebellum, and spinal cord. The lesions are areas of demyelination, gliosis, necrosis, spongiosis, or capillary proliferation. Clinical symptoms depend on which areas of the central nervous system are involved. The most common underlying cause is a defect in oxidative phosphorylation (Dahl, 1998). Leigh syndrome may be a feature of a deficiency of any of the mitochondrial respiratory chain complexes: complex I deficiency (252010), complex II deficiency (252011), complex III deficiency (124000), complex IV deficiency (cytochrome c oxidase; 220110), or complex V deficiency (604273). [from OMIM]

MedGen UID:
44095
Concept ID:
C0023264
Disease or Syndrome
3.

Prader-Willi syndrome

Prader-Willi (PWS) syndrome is characterized by severe hypotonia and feeding difficulties in early infancy, followed in later infancy or early childhood by excessive eating and gradual development of morbid obesity (unless eating is externally controlled). Motor milestones and language development are delayed. All individuals have some degree of cognitive impairment. A distinctive behavioral phenotype (with temper tantrums, stubbornness, manipulative behavior, and obsessive-compulsive characteristics) is common. Hypogonadism is present in both males and females and manifests as genital hypoplasia, incomplete pubertal development, and, in most, infertility. Short stature is common; characteristic facial features, strabismus, and scoliosis are often present, and non-insulin-dependent diabetes mellitus often occurs in obese individuals. [from GeneReviews]

MedGen UID:
46057
Concept ID:
C0032897
Congenital Abnormality
4.

Russell-Silver syndrome

Russell-Silver syndrome (RSS) is characterized by intrauterine growth retardation accompanied by postnatal growth deficiency. The birth weight of affected infants is typically two or more SD below the mean, and postnatal growth two or more SD below the mean for length or height. Affected individuals typically have proportionately short stature, normal head circumference, fifth-finger clinodactyly, typical facial features with triangular facies characterized by broad forehead and narrow chin, and limb-length asymmetry that may result from hemihypotrophy with diminished growth of the affected side. Growth velocity is normal in children with RSS. The average adult height of males is 151.2 cm and that of females is 139.9 cm. Evidence exists that children with RSS are at significant risk for developmental delay (both motor and cognitive) and learning disabilities. [from GeneReviews]

MedGen UID:
104492
Concept ID:
C0175693
Congenital Abnormality
5.

Multiple endocrine neoplasia, type 2b

Multiple endocrine neoplasia type 2 (MEN 2) is classified into three subtypes: MEN 2A, FMTC (familial medullary thyroid carcinoma), and MEN 2B. All three subtypes involve high risk for development of medullary carcinoma of the thyroid (MTC); MEN 2A and MEN 2B have an increased risk for pheochromocytoma; MEN 2A has an increased risk for parathyroid adenoma or hyperplasia. Additional features in MEN 2B include mucosal neuromas of the lips and tongue, distinctive facies with enlarged lips, ganglioneuromatosis of the gastrointestinal tract, and an asthenic ‘marfanoid’ body habitus. MTC typically occurs in early childhood in MEN 2B, early adulthood in MEN 2A, and middle age in FMTC. [from GeneReviews]

MedGen UID:
9959
Concept ID:
C0025269
Neoplastic Process
6.

Bardet-Biedl syndrome

Bardet-Biedl syndrome (BBS) is characterized by rod-cone dystrophy, truncal obesity, postaxial polydactyly, cognitive impairment, male hypogonadotrophic hypogonadism, complex female genitourinary malformations, and renal abnormalities. The visual prognosis for children with BBS is poor. Night blindness is usually evident by age seven to eight years; the mean age of legal blindness is 15.5 years. Birth weight is usually normal, but significant weight gain begins within the first year and becomes a lifelong issue for most individuals. A majority of individuals have significant learning difficulties; a minority have severe impairment on IQ testing. Renal disease is a major cause of morbidity and mortality. [from GeneReviews]

MedGen UID:
156019
Concept ID:
C0752166
Disease or Syndrome
7.

Angelman syndrome

Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs, and a unique behavior with an inappropriate happy demeanor that includes frequent laughing, smiling, and excitability. Microcephaly and seizures are also common. Developmental delays are first noted at around age six months; however, the unique clinical features of AS do not become manifest until after age one year, and it can take several years before the correct clinical diagnosis is obvious. [from GeneReviews]

MedGen UID:
58144
Concept ID:
C0162635
Disease or Syndrome
8.

Costello syndrome

Costello syndrome is characterized by failure to thrive in infancy as a result of severe postnatal feeding difficulties; short stature; developmental delay or intellectual disability; coarse facial features (full lips, large mouth, full nasal tip); curly or sparse, fine hair; loose, soft skin with deep palmar and plantar creases; papillomata of the face and perianal region; diffuse hypotonia and joint laxity with ulnar deviation of the wrists and fingers; tight Achilles tendons; and cardiac involvement including: cardiac hypertrophy (usually typical hypertrophic cardiomyopathy [HCM]), congenital heart defect (usually valvar pulmonic stenosis), and arrhythmia (usually supraventricular tachycardia, especially chaotic atrial rhythm/multifocal atrial tachycardia or ectopic atrial tachycardia). Relative or absolute macrocephaly is typical, and postnatal cerebellar overgrowth can result in the development of a Chiari I malformation with associated anomalies including hydrocephalus or syringomyelia. Individuals with Costello syndrome have an approximately 15% lifetime risk for malignant tumors including rhabdomyosarcoma and neuroblastoma in young children and transitional cell carcinoma of the bladder in adolescents and young adults. [from GeneReviews]

MedGen UID:
108454
Concept ID:
C0587248
Disease or Syndrome
9.

Walker-Warburg congenital muscular dystrophy

Congenital muscular dystrophy (CMD) is a clinically and genetically heterogeneous group of inherited muscle disorders. Muscle weakness typically presents from birth to early infancy. Affected infants typically appear "floppy" with low muscle tone and poor spontaneous movements. Affected children may present with delay or arrest of gross motor development together with joint and/or spinal rigidity. Muscle weakness may improve, worsen, or stabilize in the short term; however, with time progressive weakness and joint contractures, spinal deformities, and respiratory compromise may affect quality of life and life span. The main CMD subtypes, grouped by involved protein function and gene in which causative mutations occur, are laminin alpha-2 (merosin) deficiency (MDC1A), collagen VI-deficient CMD, the dystroglycanopathies (caused by mutations in POMT1, POMT2, FKTN, FKRP, LARGE, POMGNT1, and ISPD), SEPN1-related CMD (previously known as rigid spine syndrome, RSMD1) and LMNA-related CMD (L-CMD). Several less known CMD subtypes have been reported in a limited number of individuals. Cognitive impairment ranging from intellectual disability to mild cognitive delay, structural brain and/or eye abnormalities, and seizures are found almost exclusively in the dystroglycanopathies while white matter abnormalities without major cognitive involvement tend to be seen in the laminin alpha-2-deficient subtype. [from GeneReviews]

MedGen UID:
75553
Concept ID:
C0265221
Disease or Syndrome
10.

Pelizaeus-Merzbacher disease

PLP1-related 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. Female carriers may manifest mild to moderate signs of the disease. [from GeneReviews]

MedGen UID:
61440
Concept ID:
C0205711
Disease or Syndrome
11.

Propionic acidemia

The spectrum of propionic acidemia (PA) ranges from neonatal-onset to late-onset disease. Neonatal-onset PA, the most common form, is characterized by poor feeding, vomiting, and somnolence in the first days of life in a previously healthy infant, followed by lethargy, seizures, coma, and death. It is frequently accompanied by metabolic acidosis with anion gap, ketonuria, hypoglycemia, hyperammonemia, and cytopenias. Late-onset PA includes developmental regression, chronic vomiting, protein intolerance, failure to thrive, hypotonia, and occasionally basal ganglia infarction (resulting in dystonia and choreoathetosis) and cardiomyopathy. Affected children can have an acute decompensation that resembles the neonatal presentation and is precipitated by a catabolic stress such as infection, injury, or surgery. Isolated cardiomyopathy and arrhythmia 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 (POI), and chronic renal failure. [from GeneReviews]

MedGen UID:
75694
Concept ID:
C0268579
Disease or Syndrome
12.

Carbohydrate-deficient glycoprotein syndrome type I

PMM2-CDG (CDG-Ia) (previously known as congenital disorder of glycosylation type 1a), the most common of a group of disorders of abnormal glycosylation of N-linked oligosaccharides, is divided into three stages: infantile multisystem, late-infantile and childhood ataxia-intellectual disability, and adult stable disability. The three stages notwithstanding, clinical presentation and course are highly variable, ranging from infants who die in the first year of life to mildly involved adults. Clinical presentations tend to be similar in siblings. In the infantile multisystem stage, infants show axial hypotonia, hyporeflexia, esotropia, and developmental delay; feeding problems, vomiting, and diarrhea with failure to thrive; and impaired growth. Subcutaneous fat may be excessive over the buttocks and suprapubic region. Two distinct clinical presentations are observed: (1) a non-fatal neurologic form with strabismus, psychomotor retardation, and cerebellar hypoplasia in infancy followed by neuropathy and retinitis pigmentosa in the first or second decade and (2) a neurologic-multivisceral form with approximately 20% mortality in the first year of life. The late-infantile and childhood ataxia-intellectual disability stage, with onset between age three and ten years, is characterized by hypotonia, ataxia, severely delayed language and motor development, inability to walk, and IQ of 40 to 70; other findings include stroke-like episodes or transient unilateral loss of function, retinitis pigmentosa, joint contractures, and skeletal deformities. In the adult stable disability stage, intellectual ability is stable; peripheral neuropathy is variable, thoracic and spinal deformities progress, and premature aging is observed; females lack secondary sexual development and males may exhibit decreased testicular volume. Hyperglycemia-induced growth hormone release, hyperprolactinemia, insulin resistance, and coagulopathy may occur. An increased risk of deep venous thrombosis is present. [from GeneReviews]

MedGen UID:
138111
Concept ID:
C0349653
Disease or Syndrome
13.

Ornithine carbamoyltransferase deficiency

Ornithine transcarbamylase (OTC) deficiency can occur as a severe neonatal-onset disease in males (but rarely in females) and as a late-onset (partial) disease in males and females. Males with severe neonatal-onset OTC deficiency are typically normal at birth but become symptomatic from hyperammonemia on day two to three of life and are usually catastrophically ill by the time they come to medical attention. After successful treatment of neonatal hyperammonemic coma these infants can easily become hyperammonemic again despite appropriate treatment; they typically require liver transplant by age six months to improve quality of life. Males and heterozygous females with late-onset (partial) OTC deficiency can present from infancy to later childhood, adolescence, or adulthood. No matter how mild the disease, a hyperammonemic crisis can be precipitated by stressors and become a life-threatening event at any age and in any situation in life. For all individuals with OTC deficiency, typical neuropsychological complications include developmental delay, learning disabilities, intellectual disability, attention deficit hyperactivity disorder (ADHD), and executive function deficits. [from GeneReviews]

MedGen UID:
75692
Concept ID:
C0268542
Disease or Syndrome
14.

Citrullinemia type I

Citrullinemia type I (CTLN1) presents as a clinical spectrum that includes an acute neonatal form (the "classic" form), a milder late-onset form, a form without symptoms or hyperammonemia, and a form in which women have onset of severe symptoms during pregnancy or post partum. Distinction between the clinical forms is based on clinical findings and is not clear-cut. Infants with the acute neonatal form appear normal at birth. Shortly thereafter, they develop hyperammonemia and become progressively lethargic, feed poorly, often vomit, and may develop signs of increased intracranial pressure (ICP). Without prompt intervention, hyperammonemia and the accumulation of other toxic metabolites (e.g., glutamine) result in ICP, increased neuromuscular tone, spasticity, ankle clonus, seizures, loss of consciousness, and death. Children with the severe form who are treated promptly may survive for an indeterminate period of time, but usually with significant neurologic deficits. The late-onset form may be milder than that seen in the acute neonatal form, for unknown reasons. The episodes of hyperammonemia are similar to those seen in the acute neonatal form, but the initial neurologic findings may be more subtle because of the older age of the affected individuals. [from GeneReviews]

MedGen UID:
104491
Concept ID:
C0175683
Disease or Syndrome
15.

Mitochondrial complex I deficiency

Isolated complex I deficiency is the most common enzymatic defect of the oxidative phosphorylation disorders (McFarland et al., 2004; Kirby et al., 2004). It causes a wide range of clinical disorders, ranging from lethal neonatal disease to adult-onset neurodegenerative disorders. Phenotypes include macrocephaly with progressive leukodystrophy, nonspecific encephalopathy, hypertrophic cardiomyopathy, myopathy, liver disease, Leigh syndrome (256000), Leber hereditary optic neuropathy (535000), and some forms of Parkinson disease (see 556500) (Loeffen et al., 2000; Pitkanen et al., 1996; Robinson, 1998). Genetic Heterogeneity of Complex I Deficiency Mitochondrial complex I deficiency shows extreme genetic heterogeneity and can be caused by mutation in nuclear-encoded genes or in mitochondrial-encoded genes. There are no obvious genotype-phenotype correlations, and inference of the underlying basis from the clinical or biochemical presentation is difficult, if not impossible (summary by Haack et al., 2012). However, the majority of cases are caused by mutations in nuclear-encoded genes (Loeffen et al., 2000; Triepels et al., 2001). Complex I deficiency with autosomal recessive inheritance results from mutation in nuclear-encoded subunit genes, including NDUFV1 (161015), NDUFV2 (600532), NDUFS1 (157655), NDUFS2 (602985), NDUFS3 (603846), NDUFS4 (602694), NDUFS6 (603848), NDUFS7 (601825), NDUFS8 (602141), NDUFA2 (602137), NDUFA11 (612638), NDUFAF3 (612911), NDUFA10 (603835), NDUFB3 (603839), NDUFB9 (601445), and the complex I assembly genes B17.2L (609653), HRPAP20 (611776), C20ORF7 (612360), NUBPL (613621), and NDUFAF1 (606934). The disorder can also be caused by mutation in other nuclear-encoded genes, including FOXRED1 (613622), ACAD9 (611103; see 611126), and MTFMT (611766; see 256000). X-linked inheritance is observed with mutations in the NDUFA1 gene (300078). Complex I deficiency with mitochondrial inheritance has been associated with mutation in 6 mitochondrial-encoded components of complex I: MTND1 (516000), MTND2 (516001), MTND3 (516002), MTND4 (516003), MTND5 (516005), MTND6 (516006). Most of these patients have a phenotype of Leber hereditary optic neuropathy (LHON; 535000) or Leigh syndrome (256000). Features of complex I deficiency may also be caused by mutation in other mitochondrial genes, including MTTS2 (590085). [from OMIM]

MedGen UID:
374101
Concept ID:
C1838979
Disease or Syndrome
16.

Niemann-Pick disease, type A

Acid sphingomyelinase (ASM) deficiency has been categorized in the past as either neuronopathic (Niemann-Pick disease type A [NPD-A]), with death in early childhood, or non-neuronopathic (Niemann-Pick disease type B [NPD-B]). While forms intermediate to these two extremes occur, all ASM deficiency that is not NPD-A is designated in this review as NPD-B, despite its wide range of manifestations and severity. The first symptom in NPD-A is hepatosplenomegaly, usually noted by age three months; over time the liver and spleen become massive. Psychomotor development progresses no further than the 12-month level, after which neurologic deterioration is relentless. A classic cherry-red spot of the macula of the retina, which may not be present in the first few months, is eventually present in all affected children. Interstitial lung disease caused by storage of sphingomyelin in pulmonary macrophages results in frequent respiratory infections and often respiratory failure. Most children succumb before the third year. NPD type B, later in onset and milder in manifestations than NPD type A, is characterized by hepatosplenomegaly with progressive hypersplenism and stable liver dysfunction, gradual deterioration in pulmonary function, and atherogenic lipid profile. Progressive and/or clinically significant neurologic manifestations occur infrequently. Survival to adulthood can occur. [from GeneReviews]

MedGen UID:
78650
Concept ID:
C0268242
Disease or Syndrome
17.

Cytochrome-c oxidase deficiency

Complex IV (cytochrome c oxidase; EC 1.9.3.1) is the terminal enzyme of the respiratory chain and consists of 13 polypeptide subunits, 3 of which are encoded by mitochondrial DNA. The 3 mitochondrially encoded proteins in the cytochrome oxidase complex are the actual catalytic subunits that carry out the electron transport function (Saraste, 1983). See 123995 for discussion of some of the nuclear-encoded subunits. Shoubridge (2001) provided a comprehensive review of cytochrome c oxidase deficiency and noted that most isolated COX deficiencies are inherited as autosomal recessive disorders caused by mutations in nuclear-encoded genes; mutations in the mtDNA-encoded COX subunit genes are relatively rare. [from OMIM]

MedGen UID:
75662
Concept ID:
C0268237
Disease or Syndrome
18.

Niemann-Pick disease type C1

Niemann-Pick disease type C (NPC) is a lipid storage disease that can present in infants, children, or adults. Neonates can present with ascites and severe liver disease from infiltration of the liver and/or respiratory failure from infiltration of the lungs. Other infants, without liver or pulmonary disease, have hypotonia and developmental delay. The classic presentation occurs in mid-to-late childhood with the insidious onset of ataxia, vertical supranuclear gaze palsy (VSGP), and dementia. Dystonia and seizures are common. Dysarthria and dysphagia eventually become disabling, making oral feeding impossible; death usually occurs in the late second or third decade from aspiration pneumonia. Adults are more likely to present with dementia or psychiatric symptoms. [from GeneReviews]

MedGen UID:
465922
Concept ID:
C3179455
Disease or Syndrome
19.

Severe myoclonic epilepsy in infancy

SCN1A-related seizure disorders encompass a spectrum that ranges from simple febrile seizures (FS) and generalized epilepsy with febrile seizures plus (GEFS+) at the mild end to Dravet syndrome and intractable childhood epilepsy with generalized tonic-clonic seizures (ICE-GTC) at the severe end. Phenotypes with intractable seizures including Dravet syndrome (also known as severe myoclonic epilepsy in infancy [SMEI] or polymorphic myoclonic epilepsy in infancy [PMEI]) are usually associated with progressive dementia. Less commonly observed phenotypes include myoclonic-astatic epilepsy (MAE or Doose syndrome), Lennox-Gastaut syndrome (LGS), infantile spasms, and vaccine-related encephalopathy and seizures. The phenotype of SCN1A-related seizure disorders can vary even within the same family. [from GeneReviews]

MedGen UID:
148243
Concept ID:
C0751122
Disease or Syndrome
20.

Medium-chain acyl-coenzyme A dehydrogenase deficiency

Medium-chain acyl-coenzyme A dehydrogenase (MCAD) is one of the enzymes involved in mitochondrial fatty acid ß-oxidation, which fuels hepatic ketogenesis, a major source of energy once hepatic glycogen stores become depleted during prolonged fasting and periods of higher energy demands. In a typical clinical scenario, a previously healthy child with MCAD deficiency presents with hypoketotic hypoglycemia, vomiting, and lethargy triggered by a common illness. Seizures may occur. Hepatomegaly and liver disease are often present during an acute episode, which can quickly progress to coma and death. Children are normal at birth and – if not identified through newborn screening – typically present between ages three and 24 months; later presentation, even into adulthood, is possible. The prognosis is excellent once the diagnosis is established and frequent feedings are instituted to avoid any prolonged period of fasting. [from GeneReviews]

MedGen UID:
65086
Concept ID:
C0220710
Disease or Syndrome

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