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]

The ABO system consists of A and B antigens and antibodies against these antigens. [from HPO]

ABO phenotype O, corresponding to the genotype OO. [from HPO]

MDDGC3 is a rare form of autosomal recessive limb-girdle muscular dystrophy with normal cognition (Clement et al., 2008). It is part of a group of similar disorders resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239), collectively known as 'dystroglycanopathies' (Godfrey et al., 2007). For a discussion of genetic heterogeneity of muscular dystrophy-dystroglycanopathy type C, see MDDGC1 (609308). [from OMIM]

MDDGB3 is an autosomal recessive congenital muscular dystrophy with impaired intellectual development and mild brain abnormalities (Clement et al., 2008). It is part of a group of similar disorders resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239), collectively known as 'dystroglycanopathies' (Mercuri et al., 2009). For a discussion of genetic heterogeneity of congenital muscular dystrophy-dystroglycanopathy type B, see MDDGB1 (613155). [from OMIM]

An autosomal recessive muscular dystrophy caused by mutations in the POMGNT1 gene. It is associated with characteristic brain and eye malformations, profound mental retardation, and death usually in the first years of life. [from NCI]

Hyperphosphatasia with impaired intellectual development syndrome-2 (HPMRS2) is an autosomal recessive disorder characterized by moderately to severely delayed psychomotor development, facial dysmorphism, brachytelephalangy, and increased serum alkaline phosphatase (hyperphosphatasia). Some patients may have additional features, such as cardiac septal defects or seizures (summary by Krawitz et al., 2012). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of hyperphosphatasia with impaired intellectual development syndrome, see HPMRS1 (239300). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293). [from OMIM]

Any open-angle glaucoma in which the cause of the disease is a mutation in the NTF4 gene. [from MONDO]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the POMGNT1 gene. [from MONDO]

The nephrotic syndrome refers to a genetically heterogeneous group of disorders characterized by proteinuria, hypoalbuminemia, and edema, resulting in end-stage kidney disease if untreated. Inherited defects in podocyte structure and function have been observed in some children with the steroid-resistant subtype of nephrotic syndrome (summary by Ozaltin et al., 2011). For a general phenotypic description and a discussion of genetic heterogeneity of nephrotic syndrome, see NPHS1 (256300). [from OMIM]

Carcinomas of the biliary tract are aggressive malignancies, with 5-year survival of less than 10%. These carcinomas arise throughout the biliary tree and are anatomically classified as either intrahepatic or extrahepatic cholangiocarcinomas. Gallbladder carcinomas also arise from the biliary tree but have distinct natural histories compared to cholangiocarcinomas, suggesting different underlying tumor biology. Cholangiocarcinoma incidence varies widely between geographic regions, reflecting the impact of different underlying etiologies. In endemic areas, liver fluke infections by O. viverrini and Clonorchis sinensis, both group I carcinogens, represent the major risk factor for cholangiocarcinomas. In nonendemic regions, other risk factors, including choledochal cysts (603003), hepatolithiasis, and primary sclerosing cholangitis (613806), are likely contributors (summary by Chan-on et al., 2013). Overall, the majority of patients lack such identifiable risk factors (summary by Jiao et al., 2013). [from OMIM]

In dentin dysplasia type I, both primary and secondary dentitions are affected. The color and general morphology of the teeth are usually normal, although they may be slightly opalescent and blue or brown. Teeth may be very mobile and exfoliate spontaneously because of inadequate root formation. On radiographs, the roots are short and may be more pointed than normal. Pulp chambers are usually absent except for a chevron-shaped remnant in the crown (Witkop, 1975). Root canals are usually absent. Periapical radiolucencies may be present at the apices of affected teeth, for reasons unknown. On light microscopic examination of the permanent teeth, the coronal dentin is normal, but further apically becomes irregular, fills the pulp chamber, and has a 'sand-dune' morphology. Scanning electron microscopic studies of the deciduous and permanent teeth have been reported (Sauk et al., 1972; Melnick et al., 1980). Subclassification of Dentin Dysplasia Type I O Carroll et al. (1991) and O Carroll and Duncan (1994) reviewed dentin dysplasia and proposed 4 subtypes of dentin dysplasia type I, which they designated as DD1a-d. In DD1a, there is complete obliteration of pulp chambers and no root development, with many periapical radiolucent areas. In DD1b, there are horizontal crescent-shaped radiolucent pulpal remnants and a few millimeters of root development, with many periapical radiolucent areas. DD1c shows 2 horizontal crescent-shaped radiolucent lines and significant but incomplete root development, with or without periapical radiolucent areas. DD1d is characterized by visible pulp chambers and oval pulp stones in the coronal third of the root canal with bulging of the root around the stones and few if any periapical radiolucent areas. The authors noted that the distinctions between the subtypes of DD1 were primarily useful clinically in terms of treatment options. [from OMIM]

Metachromasia (also known as metachromacy) is a characteristic color change which certain aniline dyes exhibit when bound to particular substances or when concentrated in solution. For example, the basic dye toluidine blue becomes distinctly pink when bound to cartilage matrix. In the sense used here, the metachromasia refers to a change in color not observed with normal tissues, anomalous staining with the cationic dyes toluidine blue O and Alcian blue resulting from excessive amounts of the polyanionic glycosaminoglycans. [from HPO]

POEMS syndrome is a paraneoplastic syndrome characterized by polyradiculoneuropathy (P), organomegaly (O), endocrinopathy (E), clonal plasma cell disorder (M), and skin changes (S). Other features include papilledema, extravascular volume overload, sclerotic bone lesions, thrombocytosis/erythrocytosis, and elevated VEGF levels. [from ORDO]

An abnormality of the coronary sinus, which is formed by the union of the great cardiac vein and the left marginal vein and terminates in the right atrium. The coronary sinus functions to o collect deoxygenated blood from the myocardium of the heart and drain it into the right atrium. [from HPO]

Sandhoff disease comprises a phenotypic continuum encompassing acute infantile, subacute juvenile, and late-onset disease. Although classification into these phenotypes is somewhat arbitrary, it is helpful in understanding the variation observed in the timing of disease onset, presenting manifestations, rate of progression, and life span. Acute infantile Sandhoff disease (onset age <6 months). Infants are generally normal at birth followed by progressive weakness and slowing of developmental progress, then developmental regression and severe neurologic impairment. Seizures are common. Death usually occurs between ages two and three years. Subacute juvenile Sandhoff disease (onset age 2-5 years). After attaining normal developmental milestones, developmental progress slows, followed by developmental regression and neurologic impairment (abnormal gait, dysarthria, and cognitive decline). Death (usually from aspiration) typically occurs in the early to late teens. Late-onset Sandhoff disease (onset older teen years or young adulthood). Nearly normal psychomotor development is followed by a range of neurologic findings (e.g., weakness, spasticity, dysarthria, and deficits in cerebellar function) and psychiatric findings (e.g., deficits in executive function and memory). Life expectancy is not necessarily decreased. [from GeneReviews]

Rhizomelic chondrodysplasia punctata (RCDP) is a peroxisomal disorder characterized by disproportionately short stature primarily affecting the proximal parts of the extremities, a typical facial appearance including a broad nasal bridge, epicanthus, high-arched palate, dysplastic external ears, and micrognathia, congenital contractures, characteristic ocular involvement, dwarfism, and severe mental retardation with spasticity. Biochemically, plasmalogen synthesis and phytanic acid alpha-oxidation are defective. Most patients die in the first decade of life. RCDP1 (215100) is the most frequent form of RCDP (summary by Wanders and Waterham, 2005). Whereas RCDP1 is a peroxisomal biogenesis disorder (PBD), RCDP2 is classified as a single peroxisome enzyme deficiency (Waterham and Ebberink, 2012). For a discussion of genetic heterogeneity of rhizomelic chondrodysplasia punctata, see 215100. [from OMIM]

Choroid plexus tumors are of neuroectodermal origin and range from benign choroid plexus papillomas (CPPs) to malignant choroid carcinomas (CPCs). These rare tumors generally occur in childhood, but have also been reported in adults. Patients typically present with signs and symptoms of increased intracranial pressure including headache, hydrocephalus, papilledema, nausea, vomiting, cranial nerve deficits, gait impairment, and seizures (summary by Safaee et al., 2013). [from OMIM]

Foveal hypoplasia is defined as the lack of foveal depression with continuity of all neurosensory retinal layers in the presumed foveal area. Foveal hypoplasia as an isolated entity is a rare phenomenon; it is usually described in association with other ocular disorders, such as aniridia (106210), microphthalmia (see 251600), albinism (see 203100), or achromatopsia (see 216900). All reported cases of foveal hypoplasia have been accompanied by decreased visual acuity and nystagmus (summary by Perez et al., 2014). Genetic Heterogeneity of Foveal Hypoplasia Foveal hypoplasia-2 (FVH2; 609218) is caused by mutation in the SLC38A8 gene (615585) on chromosome 16q23. Foveal hypoplasia-3 (FVH3; 620958) is caused by mutation in the AHR gene (600253) on chromosome 7p21. [from OMIM]