MedGen

While the majority of individuals with HRAS-related Costello syndrome (Costello syndrome) share characteristic findings affecting multiple organ systems, the phenotypic spectrum is wide, ranging from a mild or attenuated phenotype to a severe phenotype with early-lethal complications. Costello syndrome is typically 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 hypertrophic cardiomyopathy), congenital heart defects (usually valvular pulmonic stenosis), and arrhythmia (usually supraventricular tachycardia, especially abnormal 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]

Junctional epidermolysis bullosa (JEB) is characterized by fragility of the skin and mucous membranes, manifest by blistering with little or no trauma. Blistering may be severe and granulation tissue can form on the skin around the oral and nasal cavities, fingers and toes, and internally around the upper airway. Blisters generally heal with no significant scarring. Broad classification of JEB includes JEB generalized severe and JEB generalized intermediate. In JEB generalized severe, blisters are present at birth or become apparent in the neonatal period. Congenital malformations of the urinary tract and bladder may also occur. In JEB generalized intermediate, the phenotype may be mild with blistering localized to hands, feet, knees, and elbows with or without renal or ureteral involvement. Some individuals never blister after the newborn period. Additional features shared by JEB and the other major forms of epidermolysis bullosa (EB) include congenital localized absence of skin (aplasia cutis congenita), milia, nail dystrophy, scarring alopecia, hypotrichosis, pseudosyndactyly, and other contractures. [from GeneReviews]

Craniofrontonasal syndrome is an X-linked developmental disorder that shows paradoxically greater severity in heterozygous females than in hemizygous males. Females have frontonasal dysplasia, craniofacial asymmetry, craniosynostosis, bifid nasal tip, grooved nails, wiry hair, and abnormalities of the thoracic skeleton, whereas males typically show only hypertelorism (Twigg et al., 2004; Wieland et al., 2004). [from OMIM]

Oculodentodigital dysplasia (ODDD) is characterized by a typical facial appearance and variable involvement of the eyes, dentition, and fingers. Characteristic facial features include a narrow, pinched nose with hypoplastic alae nasi, prominent columella and thin anteverted nares together with a narrow nasal bridge, and prominent epicanthic folds giving the impression of hypertelorism. The teeth are usually small and carious. Typical eye findings include microphthalmia and microcornea. The characteristic digital malformation is complete syndactyly of the fourth and fifth fingers (syndactyly type III) but the third finger may be involved and associated camptodactyly is a common finding (summary by Judisch et al., 1979). Neurologic abnormalities are sometimes associated (Gutmann et al., 1991), and lymphedema has been reported in some patients with ODDD (Brice et al., 2013). See review by De Bock et al. (2013). Genetic Heterogeneity of Oculodentodigital Syndrome An autosomal recessive form of ODDD (257850) is also caused by mutation in the GJA1 gene, but the majority of cases are autosomal dominant. [from OMIM]

About half of all people with trichothiodystrophy have a photosensitive form of the disorder, which causes them to be extremely sensitive to ultraviolet (UV) rays from sunlight. They develop a severe sunburn after spending just a few minutes in the sun. However, for reasons that are unclear, they do not develop other sun-related problems such as excessive freckling of the skin or an increased risk of skin cancer. Many people with trichothiodystrophy report that they do not sweat.

Trichothiodystrophy is also associated with recurrent infections, particularly respiratory infections, which can be life-threatening. People with trichothiodystrophy may have abnormal red blood cells, including red blood cells that are smaller than normal. They may also have elevated levels of a type of hemoglobin called A2, which is a protein found in red blood cells. Other features of trichothiodystrophy can include dry, scaly skin (ichthyosis); abnormalities of the fingernails and toenails; clouding of the lens in both eyes from birth (congenital cataracts); poor coordination; and skeletal abnormalities including degeneration of both hips at an early age.

Intellectual disability and delayed development are common in people with trichothiodystrophy, although most affected individuals are highly social with an outgoing and engaging personality. Some people with trichothiodystrophy have brain abnormalities that can be seen with imaging tests. A common neurological feature of this disorder is impaired myelin production (dysmyelination). Myelin is a fatty substance that insulates nerve cells and promotes the rapid transmission of nerve impulses.

Mothers of children with trichothiodystrophy may experience problems during pregnancy including pregnancy-induced high blood pressure (preeclampsia) and a related condition called HELLP syndrome that can damage the liver. Babies with trichothiodystrophy are at increased risk of premature birth, low birth weight, and slow growth. Most children with trichothiodystrophy have short stature compared to others their age. 

The signs and symptoms of trichothiodystrophy vary widely. Mild cases may involve only the hair. More severe cases also cause delayed development, significant intellectual disability, and recurrent infections; severely affected individuals may survive only into infancy or early childhood.

In people with trichothiodystrophy, tests show that the hair is lacking sulfur-containing proteins that normally gives hair its strength. A cross section of a cut hair shows alternating light and dark banding that has been described as a "tiger tail."

Trichothiodystrophy, commonly called TTD, is a rare inherited condition that affects many parts of the body. The hallmark of this condition is hair that is sparse and easily broken.  [from MedlinePlus Genetics]

Trichorhinophalangeal syndrome (TRPS) comprises TRPS I (caused by a heterozygous pathogenic variant in TRPS1) and TRPS II (caused by a contiguous gene deletion of TRPS1, RAD21, and EXT1). Both TRPS types are characterized by distinctive facial features (large nose with broad nasal ridge and tip and underdeveloped alae; thick and broad medial eyebrows; long philtrum; thin vermilion of the upper lip; and large prominent ears); ectodermal features (fine, sparse, depigmented, and slow-growing hair and dystrophic nails); and skeletal findings (short stature, brachydactyly with ulnar or radial deviation of the fingers, short feet, and early, marked hip dysplasia). TRPS II is additionally characterized by multiple osteochondromas and an increased risk of mild-to-moderate intellectual disability. [from GeneReviews]

ATP6V0A2-related cutis laxa is characterized by generalized cutis laxa, findings associated with generalized connective tissue disorder, developmental delays, and a variety of neurologic findings including abnormality on brain MRI. At birth, hypotonia, overfolded skin, and distinctive facial features are present and enlarged fontanelles are often observed. During childhood, the characteristic facial features and thick or coarse hair may become quite pronounced. The skin findings decrease with age, although easy bruising and Ehlers-Danlos-like scars have been described in some. In most (not all) affected individuals, cortical and cerebellar malformations are observed on brain MRI. Nearly all affected individuals have developmental delays, seizures, and neurologic regression. [from GeneReviews]

Dilated cardiomyopathy with woolly hair, palmoplantar keratoderma, and tooth agenesis (DCWHKTA) is an autosomal dominant disorder characterized by these cardinal features (Norgett et al., 2006). [from OMIM]

Trichodentoosseous syndrome (TDO) is an autosomal dominant disorder with complete penetrance characterized by abnormalities involving hair, teeth, and bone (summary by Nguyen et al., 2013). [from OMIM]

Mal de Meleda (MDM) is a rare autosomal recessive skin disorder characterized by transgressive palmoplantar keratoderma (PPK), keratotic skin lesions, perioral erythema, brachydactyly, and nail abnormalities (summary by Fischer et al., 2001). The PPK in MDM is often accompanied by hyperhidrosis, maceration, fetid odor, and painful fissures (Ward et al., 2003). Some patients exhibiting similar but less severe features of MDM, with milder hyperkeratosis and no nail dystrophy, lichenoid plaques, pachydermia, or distant keratosis, were previously designated as having 'Gamborg Nielsen (Norrbotten) PPK' (see NOMENCLATURE). [from OMIM]

Witteveen-Kolk syndrome (WITKOS) is an autosomal dominant disorder with characteristic distinctive facial features, microcephaly, short stature, and mildly impaired intellectual development with delayed cognitive and motor development and subtle anomalies on MRI-brain imaging (summary by Balasubramanian et al., 2021). [from OMIM]

IDEDNIK syndrome is characterized by enteropathy, poor weight gain, growth deficiency, skin manifestations (ichthyosis, erythroderma, and keratoderma), sparse hair, global developmental delay, mild-to-severe intellectual disability, and deafness. Additional manifestations can include liver disease, recurrent infections, and hematologic and ocular manifestations (photophobia, corneal scarring, and keratitis). Reduced serum ceruloplasmin and total copper levels are common. Some individuals have findings on brain MRI (cerebral atrophy, basal ganglia abnormalities, and thin corpus callosum). Death prior to age two years occurs in some individuals due to severe enteropathy or sepsis; in others survival into adulthood is reported. [from GeneReviews]

Naegeli-Franceschetti-Jadassohn syndrome (NFJS) is a rare autosomal dominant disorder of skin, hair, and teeth. It is characterized by complete absence of dermatoglyphics (fingerprint lines), a reticulate pattern of skin hyperpigmentation that tends to disappear with age, thickening of the palms and soles (palmoplantar keratoderma), and decreased sweating. Dental anomalies including enamel defects, skin blistering, and nail dystrophy have been reported in some patients. It can be distinguished from dermatopathia pigmentosa reticularis (DPR) by the latter's features of lifelong persistence of the skin hyperpigmentation, partial alopecia, and absence of dental anomalies (summary by Lugassy et al., 2006). [from OMIM]

Specific granule deficiency-2 (SGD2) is an autosomal recessive immunologic disorder characterized by recurrent infections due to defective neutrophil development. Bone marrow findings include paucity of neutrophil granulocytes, absence of granule proteins in neutrophils, abnormal megakaryocytes, and features of progressive myelofibrosis with blasts. The disorder is apparent from infancy, and patients may die in early childhood unless they undergo hematopoietic stem cell transplantation. Most patients have additional findings, including delayed development, mild dysmorphic features, tooth abnormalities, and distal skeletal defects (Witzel et al., 2017). For a discussion of genetic heterogeneity of SGD, see SGD1 (245480). [from OMIM]

Congenital heart defects and ectodermal dysplasia (CHDED) is a rare disorder characterized by these cardinal features, with additional variable features of microcephaly, craniofacial or skeletal dysmorphism, feeding difficulties, or hypotonia (Sifrim et al., 2016). [from OMIM]

Abnormal hair, joint laxity, and developmental delay (HJDD) is characterized by normal hair at birth that gradually becomes sparse, twisted, brittle, and easily broken, with pili torti and trichorrhexis nodosa observed on light microscopy. Other features include increased joint mobility and cognitive delay (summary by Sharma et al., 2019). [from OMIM]

Aplasia cutis-enamel dysplasia syndrome (ACED) is characterized by localized scalp aplasia, dental enamel anomalies, and a relatively mild neurodevelopmental disorder. A skull defect underlying the scalp aplasia has been reported in some patients (Cospain et al., 2022). [from OMIM]

Nails that easily break. [from HPO]