MedGen

Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and/or lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, and genitourinary tract – are more common in individuals with FA. [from GeneReviews]

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. [from GeneReviews]

Xeroderma pigmentosum (XP) is characterized by: Acute sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure) with marked freckle-like pigmentation of the face before age two years; Sunlight-induced ocular involvement (photophobia, severe keratitis, atrophy of the skin of the lids, ocular surface neoplasms); Greatly increased risk of sunlight-induced cutaneous neoplasms (basal cell carcinoma, squamous cell carcinoma, melanoma) within the first decade of life. Approximately 25% of affected individuals have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch reflexes, progressive sensorineural hearing loss, progressive cognitive impairment, and ataxia). The most common causes of death are skin cancer, neurologic degeneration, and internal cancer. The median age at death in persons with XP with neurodegeneration (29 years) was found to be younger than that in persons with XP without neurodegeneration (37 years). [from GeneReviews]

Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) is an autosomal dominant disorder characterized by delayed development, moderately impaired intellectual development, and optic atrophy. Most patients also have evidence of cerebral visual impairment. Dysmorphic facial features are variable and nonspecific (summary by Bosch et al., 2014). [from OMIM]

The overlapping phenotypes of neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD) represent the milder manifestations of the Zellweger syndrome spectrum (ZSS) of peroxisome biogenesis disorders. The clinical course of patients with the NALD and IRD presentation is variable and may include developmental delay, hypotonia, liver dysfunction, sensorineural hearing loss, retinal dystrophy, and visual impairment. Children with the NALD presentation may reach their teens, and those with the IRD presentation may reach adulthood (summary by Waterham and Ebberink, 2012). For a complete phenotypic description and a discussion of genetic heterogeneity of PBD(NALD/IRD), see 601539. Individuals with mutations in the PEX2 gene have cells of complementation group 5 (CG5, equivalent to CG10 and CGF). For information on the history of PBD complementation groups, see 214100. [from OMIM]

The peroxisomal biogenesis disorder (PBD) Zellweger syndrome (ZS) is an autosomal recessive multiple congenital anomaly syndrome. Affected children present in the newborn period with profound hypotonia, seizures, and inability to feed. Characteristic craniofacial anomalies, eye abnormalities, neuronal migration defects, hepatomegaly, and chondrodysplasia punctata are present. Children with this condition do not show any significant development and usually die in the first year of life (summary by Steinberg et al., 2006). For a complete phenotypic description and a discussion of genetic heterogeneity of Zellweger syndrome, see 214100. Individuals with PBDs of complementation group 5 (CG5, equivalent to CG10 and CGF) have mutations in the PEX2 gene. For information on the history of PBD complementation groups, see 214100. [from OMIM]

CMTDIF is an autosomal dominant neurologic disorder characterized by onset around adolescence of slowly progressive distal muscle atrophy and weakness affecting the upper and lower limbs and resulting in steppage gait. There is distal sensory impairment with decreased reflexes. Nerve conduction velocities are variable, ranging from the demyelinating to the axonal range (summary by Soong et al., 2013). For a discussion of genetic heterogeneity of CMTDI, see 606482. [from OMIM]

VACTERL describes a constellation of congenital anomalies, including vertebral anomalies, anal atresia, congenital cardiac disease, tracheoesophageal fistula, renal anomalies, radial dysplasia, and other limb defects; see 192350. Cases of familial VACTERL with hydrocephalus (H) have been reported with suggestion of autosomal recessive or X-linked inheritance (see 314390). Other patients thought to have VACTERL-H, including 2 unrelated infants reported by Porteous et al. (1992), had been found to have Fanconi anemia (see 227650). Porteous et al. (1992) suggested that chromosomal breakage studies should be performed in all cases of VACTERL/VACTERL-H to rule out Fanconi anemia. Alter et al. (2007) noted that a VATER phenotype had been reported in Fanconi anemia of complementation groups A (227650), C (227645), D1 (605724), E (600901), F (603467), and G (614082). X-linked VACTERL-H is also associated with mutations in the FANCB gene (300515). [from OMIM]

Van den Ende-Gupta syndrome (VDEGS) is an autosomal recessive disorder characterized by severe contractual arachnodactyly from birth and distinctive facial dysmorphism, including triangular face, malar hypoplasia, narrow nose, everted lips, and blepharophimosis. Skeletal anomalies include slender ribs, hooked clavicles, and dislocated radial head. There is no neurologic involvement (summary by Patel et al., 2014). [from OMIM]

Congenital aplastic deformities of the breast include amastia (total absence of breasts and nipple), athelia (absence of the nipple), and amazia (absence of the mammary gland). Most common is amastia. Bilateral absence of the breasts may occur as an isolated anomaly or may be associated with a syndrome or a cluster of other anomalies, including anhidrotic ectodermal dysplasia (305100) or Poland syndrome (173800) (summary by Papadimitriou et al., 2009). For a discussion of genetic heterogeneity of aplasia or hypoplasia of the breasts and/or nipples, see 113700. [from OMIM]

Acropectorovertebral dysgenesis, or F syndrome, is an autosomal dominant skeletal dysplasia characterized by carpal and tarsal synostoses, syndactyly between the first and second fingers, hypodactyly and polydactyly of feet, and abnormalities of the sternum and spine (summary by Thiele et al., 2004). [from OMIM]

A severe form of lissencephaly with cerebellar hypoplasia with main features microcephaly of at least 3 standard deviations and a thick cortex associated with complete absence of the corpus callosum. [from SNOMEDCT_US]

Hereditary persistence of fetal hemoglobin (HPFH) associated with beta-thalassemia (see this term) is characterized by high hemoglobin (Hb) F levels and an increased number of fetal-Hb-containing-cells. [from ORDO]

Lissencephaly with cerebellar hypoplasia (LCH) is a variant form of lissencephaly and involves a heterogeneous group of cortical malformations without severe congenital microcephaly (>-3 SD). LCH is characterized by cerebellar underdevelopment ranging from vermian hypoplasia to total aplasia with classical or cobblestone lissencephaly. The phenotypic features of LCH include small head circumference (between -2 and -3 standard deviations (SD) forage) at birth and postnatally, moderate to severe intellectual disability, hypotonia and spasticity. Seizures are often observed and infantile spasms have been reported in some rare cases. LCH has been classified into six subgroups according to neuroradiographic properties and are classified LCH type A to F. [from ORDO]

The phenotype of acid sphingomyelinase deficiency (ASMD) occurs along a continuum. Individuals with the severe early-onset form, infantile neurovisceral ASMD, were historically diagnosed with Niemann-Pick disease type A (NPD-A). The later-onset, chronic visceral form of ASMD is also referred to as Niemann-Pick disease type B (NPD-B). A phenotype with intermediate severity is also known as chronic neurovisceral ASMD (NPD-A/B). The most common presenting symptom in NPD-A is hepatosplenomegaly, usually detectable by age three months; over time the liver and spleen become massive in size. Psychomotor development progresses no further than the 12-month level, after which neurologic deterioration is relentless. Failure to thrive typically becomes evident by the second year of life. 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 of life. NPD-B generally presents later than NPD-A, and the manifestations are less severe. NPD-B is characterized by progressive hepatosplenomegaly, gradual deterioration in liver and pulmonary function, osteopenia, and atherogenic lipid profile. No central nervous system (CNS) manifestations occur. Individuals with NPD-A/B have symptoms that are intermediate between NPD-A and NPD-B. The presentation in individuals with NPD-A/B varies greatly, although all are characterized by the presence of some CNS manifestations. Survival to adulthood can occur in individuals with NPD-B and NPD-A/B. [from GeneReviews]

Beta-thalassemia (ß-thalassemia) is characterized by reduced synthesis of the hemoglobin subunit beta (hemoglobin beta chain) that results in microcytic hypochromic anemia, an abnormal peripheral blood smear with nucleated red blood cells, and reduced amounts of hemoglobin A (HbA) on hemoglobin analysis. Individuals with thalassemia major have severe anemia and hepatosplenomegaly; they usually come to medical attention within the first two years of life. Without treatment, affected children have severe failure to thrive and shortened life expectancy. Treatment with a regular transfusion program and chelation therapy, aimed at reducing transfusion iron overload, allows for normal growth and development and may improve the overall prognosis. Individuals with thalassemia intermedia present later and have milder anemia that does not require regular treatment with blood transfusion. These individuals are at risk for iron overload secondary to increased intestinal absorption of iron as a result of ineffective erythropoiesis. [from GeneReviews]

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.

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.

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.

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]

Usher syndrome type I (USH1) is characterized by congenital, bilateral, profound sensorineural hearing loss, vestibular areflexia, and adolescent-onset retinitis pigmentosa (RP). Unless fitted with a cochlear implant, individuals do not typically develop speech. RP, a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina, develops in adolescence, resulting in progressively constricted visual fields and impaired visual acuity. [from GeneReviews]