MedGen

Sickle cell disease (SCD) is characterized by intermittent vaso-occlusive events and chronic hemolytic anemia. Vaso-occlusive events result in tissue ischemia leading to acute and chronic pain as well as organ damage that can affect any organ system, including the bones, spleen, liver, brain, lungs, kidneys, and joints. Dactylitis (pain and/or swelling of the hands or feet) is often the earliest manifestation of SCD. In children, the spleen can become engorged with blood cells in a "splenic sequestration." The spleen is particularly vulnerable to infarction and the majority of individuals with SCD who are not on hydroxyurea or transfusion therapy become functionally asplenic in early childhood, increasing their risk for certain types of bacterial infections, primarily encapsulated organisms. Acute chest syndrome (ACS) is a major cause of mortality in SCD. Chronic hemolysis can result in varying degrees of anemia, jaundice, cholelithiasis, and delayed growth and sexual maturation as well as activating pathways that contribute to the pathophysiology directly. Individuals with the highest rates of hemolysis are at higher risk for pulmonary artery hypertension, priapism, and leg ulcers and may be relatively protected from vaso-occlusive pain. [from GeneReviews]

Any hereditary breast ovarian cancer syndrome in which the cause of the disease is a mutation in the RAD51D gene. [from MONDO]

Any hereditary breast ovarian cancer syndrome in which the cause of the disease is a mutation in the RAD51C gene. [from MONDO]

Lynch syndrome is characterized by an increased risk for colorectal cancer (CRC) and cancers of the endometrium, ovary, stomach, small bowel, urinary tract, biliary tract, brain (usually glioblastoma), skin (sebaceous adenomas, sebaceous carcinomas, and keratoacanthomas), pancreas, and prostate. Cancer risks and age of onset vary depending on the associated gene. Several other cancer types have been reported to occur in individuals with Lynch syndrome (e.g., breast, sarcomas, adrenocortical carcinoma). However, the data are not sufficient to demonstrate that the risk of developing these cancers is increased in individuals with Lynch syndrome. [from GeneReviews]

A heterozygous state in which a person has a hemoglobin S allele along with a beta-thalassemia allele. The severity of the condition is determined to a large extent by the quantity of normal hemoglobin produced by the beta-thalassemia gene. [from NCI]

Lynch syndrome is characterized by an increased risk for colorectal cancer (CRC) and cancers of the endometrium, ovary, stomach, small bowel, urinary tract, biliary tract, brain (usually glioblastoma), skin (sebaceous adenomas, sebaceous carcinomas, and keratoacanthomas), pancreas, and prostate. Cancer risks and age of onset vary depending on the associated gene. Several other cancer types have been reported to occur in individuals with Lynch syndrome (e.g., breast, sarcomas, adrenocortical carcinoma). However, the data are not sufficient to demonstrate that the risk of developing these cancers is increased in individuals with Lynch syndrome. [from GeneReviews]

Heterozygous protein S deficiency, like protein C deficiency (176860), is characterized by recurrent venous thrombosis. Bertina (1990) classified protein S deficiency into 3 clinical subtypes based on laboratory findings. Type I refers to deficiency of both free and total protein S as well as decreased protein S activity; type II shows normal plasma values, but decreased protein S activity; and type III shows decreased free protein S levels and activity, but normal total protein S levels. Approximately 40% of protein S circulates as a free active form, whereas the remaining 60% circulates as an inactive form bound to C4BPA (120830). Zoller et al. (1995) observed coexistence of type I and type III PROS1-deficient phenotypes within a single family and determined that the subtypes are allelic. Under normal conditions, the concentration of protein S exceeds that of C4BPA by approximately 30 to 40%. Thus, free protein S is the molar surplus of protein S over C4BPA. Mild protein S deficiency will thus present with selective deficiency of free protein S, whereas more pronounced protein S deficiency will also decrease the complexed protein S and consequently the total protein S level. These findings explained why assays for free protein S have a higher predictive value for protein S deficiency. See also autosomal recessive thrombophilia due to protein S deficiency (THPH6; 614514), which is a more severe disorder. [from OMIM]

Marinesco-Sjögren syndrome (MSS) is characterized by cerebellar ataxia with cerebellar atrophy, dysarthria, nystagmus, early-onset (not necessarily congenital) cataracts, myopathy, muscle weakness, and hypotonia. Additional features may include psychomotor delay, hypergonadotropic hypogonadism, short stature, and various skeletal abnormalities. Children with MSS usually present with muscular hypotonia in early infancy; distal and proximal muscular weakness is noticed during the first decade of life. Later, cerebellar findings of truncal ataxia, dysdiadochokinesia, nystagmus, and dysarthria become apparent. Motor function worsens progressively for some years, then stabilizes at an unpredictable age and degree of severity. Cataracts can develop rapidly and typically require lens extraction in the first decade of life. Although many adults have severe disabilities, life span in MSS appears to be near normal. [from GeneReviews]

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 (see 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 resulting from mutation in nuclear-encoded genes include MC1DN1, caused by mutation in the NDUFS4 gene (602694); MC1DN2 (618222), caused by mutation in the NDUFS8 gene (602141); MC1DN3 (618224), caused by mutation in the NDUFS7 gene (601825); MC1DN4 (618225), caused by mutation in the NDUFV1 gene (161015); MC1DN5 (618226), caused by mutation in the NDUFS1 gene (157655); MC1DN6 (618228), caused by mutation in the NDUFS2 gene (602985); MC1DN7 (618229), caused by mutation in the NDUFV2 gene (600532); MC1DN8 (618230), caused by mutation in the NDUFS3 gene (603846); MC1DN9 (618232), caused by mutation in the NDUFS6 gene (603848); MC1DN10 (618233), caused by mutation in the NDUFAF2 gene (609653); MC1DN11 (618234), caused by mutation in the NDUFAF1 gene (606934); MC1DN12 (301020), caused by mutation in the NDUFA1 gene (300078); MC1DN13 (618235), caused by mutation in the NDUFA2 gene (602137); MC1DN14 (618236), caused by mutation in the NDUFA11 gene (612638); MC1DN15 (618237), caused by mutation in the NDUFAF4 gene (611776); MC1DN16 (618238), caused by mutation in the NDUFAF5 gene (612360); MC1DN17 (618239), caused by mutation in the NDUFAF6 gene (612392); MC1DN18 (618240), caused by mutation in the NDUFAF3 gene (612911); MC1DN19 (618241), caused by mutation in the FOXRED1 gene (613622); MC1DN20 (611126), caused by mutation in the ACAD9 gene (611103); MC1DN21 (618242), caused by mutation in the NUBPL gene (613621); MC1DN22 (618243), caused by mutation in the NDUFA10 gene (603835); MC1DN23 (618244), caused by mutation in the NDUFA12 gene (614530); MC1DN24 (618245), caused by mutation in the NDUFB9 gene (601445); MC1DN25 (618246), caused by mutation in the NDUFB3 gene (603839); MC1DN26 (618247), caused by mutation in the NDUFA9 gene (603834); MC1DN27 (618248), caused by mutation in the MTFMT gene (611766); MC1DN28 (618249), caused by mutation in the NDUFA13 gene (609435); MC1DN29 (618250), caused by mutation in the TMEM126B gene (615533); MC1DN30 (301021), caused by mutation in the NDUFB11 gene (300403); MC1DN31 (618251), caused by mutation in the TIMMDC1 gene (615534); MC1DN32 (618252), caused by mutation in the NDUFB8 gene (602140); MC1DN33 (618253), caused by mutation in the NDUFA6 gene (602138); MC1DN34 (618776), caused by mutation in the NDUFAF8 gene (618461); MC1DN35 (619003), caused by mutation in the NDUFB10 gene (603843); MC1DN36 (619170), caused by mutation in the NDUFC2 gene (603845); MC1DN37 (619272), caused by mutation in the NDUFA8 gene (603359); MC1DN38 (619382), caused by mutation in the DNAJC30 gene (618202); and MC1DN39 (620135), caused by mutation in the NDUFB7 gene (603842). 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. Features of complex I deficiency may also be caused by mutation in other mitochondrial genes, including MTTS2 (590085). [from OMIM]

Lynch syndrome-4 (LYNCH4), or hereditary nonpolyposis colorectal cancer type 4 (HNPCC4), is an autosomal dominant disorder characterized primarily by the development of early-onset colorectal cancer. It is associated with the development of a variety of epithelial tumors that include endometrial cancer, stomach cancer, and ovarian cancer (summary by Thompson et al., 2004). [from OMIM]

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]

Charcot-Marie-Tooth disease type 4J is an autosomal recessive progressive neurologic disorder with a highly variable phenotype and onset ranging from early childhood to adulthood. Most patients have both proximal and distal asymmetric muscle weakness of the upper and lower limbs. There is significant motor dysfunction, followed by variably progressive sensory loss, which may be mild. Nerve conduction studies and nerve biopsies indicate demyelination as well as axonal loss (summary by Nicholson et al., 2011). For a phenotypic description and a discussion of genetic heterogeneity of autosomal recessive demyelinating Charcot-Marie-Tooth disease, see CMT4A (214400). [from OMIM]

Congenital dyserythropoietic anemia type II (CDA II) is the most common form of CDA (see this term) characterized by anemia, jaundice and splenomegaly and often leading to liver iron overload and gallstones. [from ORDO]

Cornelia de Lange syndrome (CdLS) encompasses a spectrum of findings from mild to severe. Severe (classic) CdLS is characterized by distinctive facial features, growth restriction (prenatal onset; <5th centile throughout life), hypertrichosis, and upper-limb reduction defects that range from subtle phalangeal abnormalities to oligodactyly (missing digits). Craniofacial features include synophrys, highly arched and/or thick eyebrows, long eyelashes, short nasal bridge with anteverted nares, small widely spaced teeth, and microcephaly. Individuals with a milder phenotype have less severe growth, cognitive, and limb involvement, but often have facial features consistent with CdLS. Across the CdLS spectrum IQ ranges from below 30 to 102 (mean: 53). Many individuals demonstrate autistic and self-destructive tendencies. Other frequent findings include cardiac septal defects, gastrointestinal dysfunction, hearing loss, myopia, and cryptorchidism or hypoplastic genitalia. [from GeneReviews]

Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of retinal dystrophies characterized by a progressive degeneration of photoreceptors, eventually resulting in severe visual impairment. For a discussion of genetic heterogeneity of RP, see 268000. [from OMIM]

An autosomal dominant form of amyotrophic lateral sclerosis caused by mutation(s) in the FIG4 gene, encoding polyphosphoinositide phosphatase. [from NCI]

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. [from GeneReviews]

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]

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. [from GeneReviews]

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. [from GeneReviews]