MedGen

Mitochondrial complex IV deficiency nuclear type 1 (MC4DN1) is an autosomal recessive metabolic disorder characterized by rapidly progressive neurodegeneration and encephalopathy with loss of motor and cognitive skills between about 5 and 18 months of age after normal early development. Affected individuals show hypotonia, failure to thrive, loss of the ability to sit or walk, poor communication, and poor eye contact. Other features may include oculomotor abnormalities, including slow saccades, strabismus, ophthalmoplegia, and nystagmus, as well as deafness, apneic episodes, ataxia, tremor, and brisk tendon reflexes. Brain imaging shows bilateral symmetric lesions in the basal ganglia, consistent with a clinical diagnosis of Leigh syndrome (see 256000). Some patients may also have abnormalities in the brainstem and cerebellum. Laboratory studies usually show increased serum and CSF lactate and decreased levels and activity of mitochondrial respiratory complex IV in patient tissues. There is phenotypic variability, but death in childhood, often due to central respiratory failure, is common (summary by Tiranti et al., 1998; Tiranti et al., 1999; Teraoka et al., 1999; Poyau et al., 2000) Genetic Heterogeneity of Mitochondrial Complex IV Deficiency 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 (Shoubridge, 2001; Sacconi et al., 2003). Mitochondrial complex IV deficiency caused by mutation in nuclear-encoded genes, in addition to MC4DN1, include MC4DN2 (604377), caused by mutation in the SCO2 gene (604272); MC4DN3 (619046), caused by mutation in the COX10 gene (602125); MC4DN4 (619048), caused by mutation in the SCO1 gene (603664); MC4DN5 (220111), caused by mutation in the LRPPRC gene (607544); MC4DN6 (615119), caused by mutation in the COX15 gene (603646); MC4DN7 (619051), caused by mutation in the COX6B1 gene (124089); MC4DN8 (619052), caused by mutation in the TACO1 gene (612958); MC4DN9 (616500), caused by mutation in the COA5 gene (613920); MC4DN10 (619053), caused by mutation in the COX14 gene (614478); MC4DN11 (619054), caused by mutation in the COX20 gene (614698); MC4DN12 (619055), caused by mutation in the PET100 gene (614770); MC4DN13 (616501), caused by mutation in the COA6 gene (614772); MC4DN14 (619058), caused by mutation in the COA3 gene (614775); MC4DN15 (619059), caused by mutation in the COX8A gene (123870); MC4DN16 (619060), caused by mutation in the COX4I1 gene (123864); MC4DN17 (619061), caused by mutation in the APOPT1 gene (616003); MC4DN18 (619062), caused by mutation in the COX6A2 gene (602009); MC4DN19 (619063), caused by mutation in the PET117 gene (614771); MC4DN20 (619064), caused by mutation in the COX5A gene (603773); MC4DN21 (619065), caused by mutation in the COXFA4 gene (603883); MC4DN22 (619355), caused by mutation in the COX16 gene (618064); and MC4DN23 (620275), caused by mutation in the COX11 gene (603648). Mitochondrial complex IV deficiency has been associated with mutations in several mitochondrial genes, including MTCO1 (516030), MTCO2 (516040), MTCO3 (516050), MTTS1 (590080), MTTL1 (590050), and MTTN (590010). [from OMIM]

Nonmedullary thyroid cancer (NMTC) comprises thyroid cancers of follicular cell origin and accounts for more than 95% of all thyroid cancer cases. The remaining cancers originate from parafollicular cells (medullary thyroid cancer, MTC; 155240). NMTC is classified into 4 groups: papillary, follicular (188470), Hurthle cell (607464), and anaplastic. Approximately 5% of NMTC is hereditary, occurring as a component of a familial cancer syndrome (e.g., familial adenomatous polyposis, 175100; Carney complex, 160980) or as a primary feature (familial NMTC or FNMTC). Papillary thyroid cancer (PTC) is the most common histologic subtype of FNMTC, accounting for approximately 85% of cases (summary by Vriens et al., 2009). PTC is characterized by distinctive nuclear alterations including pseudoinclusions, grooves, and chromatin clearing. PTCs smaller than 1 cm are referred to as papillary microcarcinomas. These tumors have been identified in up to 35% of individuals at autopsy, suggesting that they may be extremely common although rarely clinically relevant. PTC can also be multifocal but is typically slow-growing with a tendency to spread to lymph nodes and usually has an excellent prognosis (summary by Bonora et al., 2010). Genetic Heterogeneity of Susceptibility to Nonmedullary Thyroid Cancer Other susceptibilities to nonmedullary thyroid cancer include NMTC2 (188470), caused by mutation in the SRGAP1 gene (606523); NMTC3 (606240), mapped to chromosome 2q21; NMTC4 (616534), caused by mutation in the FOXE1 gene (602617); and NMTC5 (616535), caused by mutation in the HABP2 gene (603924). A susceptibility locus for familial nonmedullary thyroid carcinoma with or without cell oxyphilia (TCO; 603386) has been mapped to chromosome 19p. [from OMIM]

Familial hypercholesterolemia (FH) is characterized by significantly elevated low-density lipoprotein cholesterol (LDL-C) that leads to atherosclerotic plaque deposition in the coronary arteries and proximal aorta at an early age and increases the risk of premature cardiovascular events such as angina and myocardial infarction; stroke occurs more rarely. Xanthomas (cholesterol deposits in tendons) may be visible in the Achilles tendons or tendons of the hands and worsen with age as a result of extremely high cholesterol levels. Xanthelasmas (yellowish, waxy deposits) can occur around the eyelids. Individuals with FH may develop corneal arcus (white, gray, or blue opaque ring in the corneal margin as a result of cholesterol deposition) at a younger age than those without FH. Individuals with a more severe phenotype, often as a result of biallelic variants, can present with very significant elevations in LDL-C (>500 mg/dL), early-onset coronary artery disease (CAD; presenting as early as childhood in some), and calcific aortic valve disease. [from GeneReviews]

Classic hereditary persistence of fetal hemoglobin (HPFH) is characterized by a substantial elevation of fetal hemoglobin (HbF) in adult red blood cells. There are no other phenotypic or hematologic manifestations. Expression of the HBG1 and HBG2 genes, which encode the gamma isoforms of HbF, is normally suppressed shortly before birth and replaced by expression of the beta- (HBB; 141900) or delta- (HBD; 142000) chains, which form adult hemoglobin. Adults normally have less than 1% HbF, whereas heterozygotes for HPFH have 5 to 30% HbF. HPFH heterozygotes have essentially normal red cell indices and a rather homogeneous distribution of HbF among red cells, termed 'pancellular.' Homozygotes for HPFH can express HbF in up to 100% of red blood cells (Thein and Craig, 1998). Delta-beta thalassemia is a hemoglobin disorder characterized by decreased or absent synthesis of the delta- and beta-globin chains with a compensatory increase in expression of fetal gamma-chain synthesis from the affected chromosome. Individuals with delta-beta thalassemia have hypochromic, microcytic anemia and increased HbF, which may mitigate the anemia depending on the level of HbF. Delta-beta thalassemia and some forms of HPFH result from deletions within the beta-globin gene cluster on chromosome 11p15; this has been referred to as 'deletional' HPFH. HPFH can also result from point mutations in the promoter regions of the gamma globulin genes HBG1 and HBG2; this has been referred to as 'non-deletional' HPFH (Ottolenghi et al., 1982; Forget, 1998). Forget (1998) noted that HPFH and delta-beta thalassemia are not clearly distinct disorders, but rather show partially overlapping features that may defy classification. Higher expression of HbF is often termed 'pancellular,' whereas lower expression of HbF is often termed 'heterocellular,' although these represent a spectrum. Approximately 10% of the population has HPFH manifest as modest elevations of HbF (1 to 4%) present in a subset of red cells (about 4.5%) termed F cells. This is also sometimes referred to as 'heterocellular' HPFH, and is considered to be a multifactorial trait influenced by multiple genetic loci (Thein and Craig, 1998). [from OMIM]

A clonal expansion of myeloid blasts in the bone marrow, blood or other tissues. The classification of acute myeloid leukemias (AMLs) encompasses four major categories: 1) AML with recurrent genetic abnormalities; 2) AML with multilineage dysplasia; 3) Therapy-related AML; 4) AML not otherwise specified. The required bone marrow or peripheral blood blast percentage for the diagnosis of AML is 20% (WHO classification) [from NCBI]

Dyslexia is a disorder manifested by difficulty learning to read despite conventional instruction, adequate intelligence, and sociocultural opportunity. It is among the most common neurodevelopmental disorders, with a prevalence of 5 to 12%. Although there is evidence for familial clustering and heritability, the disorder is considered a complex multifactorial trait (Schumacher et al., 2007). Genetic Heterogeneity of Susceptibility to Dyslexia Additional dyslexia susceptibility loci include DYX2 (600202) on chromosome 6p22, DYX3 (604254) on chromosome 2p16-p15, DYX5 (606896) on chromosome 3p12-q13, DYX6 (606616) on chromosome 18p11.2, DYX8 (608995) on chromosome 1p36-p34, and DYX9 (300509) on chromosome Xq27.3. See MAPPING for other possible dyslexia susceptibility loci, including DYX4 and DYX7. [from OMIM]

Maturity-onset diabetes of the young (MODY) is a group of several conditions characterized by abnormally high levels of blood glucose, also called blood sugar. These forms of diabetes typically begin before age 30, although they can occur later in life. In MODY, elevated blood glucose arises from reduced production of insulin, which is a hormone produced in the pancreas that helps regulate blood glucose levels. Specifically, insulin controls how much glucose (a type of sugar) is passed from the blood into cells, where it is used as an energy source.

The different types of MODY are distinguished by their genetic causes. The most common types are HNF1A-MODY (also known as MODY3), accounting for 50 to 70 percent of cases, and GCK-MODY (MODY2), accounting for 30 to 50 percent of cases. Less frequent types include HNF4A-MODY (MODY1) and renal cysts and diabetes (RCAD) syndrome (also known as HNF1B-MODY or MODY5), which each account for 5 to 10 percent of cases. At least ten other types have been identified, and these are very rare.

HNF1A-MODY and HNF4A-MODY have similar signs and symptoms that develop slowly over time. Early signs and symptoms in these types are caused by high blood glucose and may include frequent urination (polyuria), excessive thirst (polydipsia), fatigue, blurred vision, weight loss, and recurrent skin infections. Over time uncontrolled high blood glucose can damage small blood vessels in the eyes and kidneys. Damage to the light-sensitive tissue at the back of the eye (the retina) causes a condition known as diabetic retinopathy that can lead to vision loss and eventual blindness. Kidney damage (diabetic nephropathy) can lead to kidney failure and end-stage renal disease (ESRD). While these two types of MODY are very similar, certain features are particular to each type. For example, babies with HNF4A-MODY tend to weigh more than average or have abnormally low blood glucose at birth, even though other signs of the condition do not occur until childhood or young adulthood. People with HNF1A-MODY have a higher-than-average risk of developing noncancerous (benign) liver tumors known as hepatocellular adenomas.

GCK-MODY is a very mild type of the condition. People with this type have slightly elevated blood glucose levels, particularly in the morning before eating (fasting blood glucose). However, affected individuals often have no symptoms related to the disorder, and diabetes-related complications are extremely rare.

RCAD is associated with a combination of diabetes and kidney or urinary tract abnormalities (unrelated to the elevated blood glucose), most commonly fluid-filled sacs (cysts) in the kidneys. However, the signs and symptoms are variable, even within families, and not everyone with RCAD has both features. Affected individuals may have other features unrelated to diabetes, such as abnormalities of the pancreas or liver or a form of arthritis called gout. [from MedlinePlus Genetics]

With proper treatment, children with Wilms tumor have a 90 percent survival rate. However, the risk that the cancer will come back (recur) is between 15 and 50 percent, depending on traits of the original tumor. Tumors usually recur in the first 2 years following treatment and develop in the kidneys or other tissues, such as the lungs. Individuals who have had Wilms tumor may experience related health problems or late effects of their treatment in adulthood, such as decreased kidney function, heart disease, and development of additional cancers.

Wilms tumor can develop in one or both kidneys. About 5 to 10 percent of affected individuals develop multiple tumors in one or both kidneys. Wilms tumor may spread from the kidneys to other parts of the body (metastasize). In rare cases, Wilms tumor does not involve the kidneys and occurs instead in the genital tract, bladder, abdomen, chest, or lower back. It is unclear how Wilms tumor develops in these tissues.

Wilms tumor is often first noticed because of abdominal swelling or a mass in the kidney that can be felt upon physical examination. Some affected children have abdominal pain, fever, a low number of red blood cells (anemia), blood in the urine (hematuria), or high blood pressure (hypertension). Additional signs of Wilms tumor can include loss of appetite, weight loss, nausea, vomiting, and tiredness (lethargy).

Wilms tumor is a form of kidney cancer that primarily develops in children. Nearly all cases of Wilms tumor are diagnosed before the age of 10, with two-thirds being found before age 5. [from MedlinePlus Genetics]

Pendred syndrome / nonsyndromic enlarged vestibular aqueduct (PDS/NSEVA) comprises a phenotypic spectrum of sensorineural hearing loss (SNHL) that is usually congenital and often severe to profound (although mild-to-moderate progressive hearing impairment also occurs), vestibular dysfunction, and temporal bone abnormalities (bilateral enlarged vestibular aqueduct with or without cochlear hypoplasia). PDS also includes development of euthyroid goiter in late childhood to early adulthood whereas NSEVA does not. [from GeneReviews]

Neural tube defects have a birth incidence of approximately 1 in 1,000 in American Caucasians and are the second most common type of birth defect after congenital heart defects. The most common NTDs are open spina bifida (myelomeningocele) and anencephaly (206500) (Detrait et al., 2005). Women with elevated plasma homocysteine, low folate, or low vitamin B12 (cobalamin) are at increased risk of having a child with a neural tube defect (O'Leary et al., 2005). Motulsky (1996) cited evidence from the Centers for Disease Control ( Anonymous, 1992) that folic acid given before and during the first 4 weeks of pregnancy can prevent 50% or more of neural tube defects. Botto et al. (1999) and Detrait et al. (2005) provided reviews of neural tube defects. De Marco et al. (2006) provided a detailed review of neurulation and the possible etiologies of neural tube defects. [from OMIM]

AP-4-associated hereditary spastic paraplegia (HSP), also known as AP-4 deficiency syndrome, is a group of neurodegenerative disorders characterized by a progressive, complex spastic paraplegia with onset typically in infancy or early childhood. Early-onset hypotonia evolves into progressive lower-extremity spasticity. The majority of children become nonambulatory and usually wheelchair bound. Over time spasticity progresses to involve the upper extremities, resulting in a spastic tetraplegia. Associated complications include dysphagia, contractures, foot deformities, dysregulation of bladder and bowel function, and a pseudobulbar affect. About 50% of affected individuals have seizures. Postnatal microcephaly (usually in the -2SD to -3SD range) is common. All have developmental delay. Speech development is significantly impaired and many affected individuals remain nonverbal. Intellectual disability in older children is usually moderate to severe. [from GeneReviews]

Mucopolysaccharidosis type I (MPS I) is a progressive multisystem disorder with features ranging over a continuum of severity. While affected individuals have traditionally been classified as having one of three MPS I syndromes (Hurler syndrome, Hurler-Scheie syndrome, or Scheie syndrome), no easily measurable biochemical differences have been identified and the clinical findings overlap. Affected individuals are best described as having either a phenotype consistent with either severe (Hurler syndrome) or attenuated MPS I, a distinction that influences therapeutic options. Severe MPS I. Infants appear normal at birth. Typical early manifestations are nonspecific (e.g., umbilical or inguinal hernia, frequent upper respiratory tract infections before age 1 year). Coarsening of the facial features may not become apparent until after age one year. Gibbus deformity of the lower spine is common and often noted within the first year. Progressive skeletal dysplasia (dysostosis multiplex) involving all bones is universal, as is progressive arthropathy involving most joints. By age three years, linear growth decreases. Intellectual disability is progressive and profound but may not be readily apparent in the first year of life. Progressive cardiorespiratory involvement, hearing loss, and corneal clouding are common. Without treatment, death (typically from cardiorespiratory failure) usually occurs within the first ten years of life. Attenuated MPS I. Clinical onset is usually between ages three and ten years. The severity and rate of disease progression range from serious life-threatening complications leading to death in the second to third decade, to a normal life span complicated by significant disability from progressive joint manifestations and cardiorespiratory disease. While some individuals have no neurologic involvement and psychomotor development may be normal in early childhood, learning disabilities and psychiatric manifestations can be present later in life. Hearing loss, cardiac valvular disease, respiratory involvement, and corneal clouding are common. [from GeneReviews]

Maturity-onset diabetes of the young (MODY) is a group of several conditions characterized by abnormally high levels of blood glucose, also called blood sugar. These forms of diabetes typically begin before age 30, although they can occur later in life. In MODY, elevated blood glucose arises from reduced production of insulin, which is a hormone produced in the pancreas that helps regulate blood glucose levels. Specifically, insulin controls how much glucose (a type of sugar) is passed from the blood into cells, where it is used as an energy source.

The different types of MODY are distinguished by their genetic causes. The most common types are HNF1A-MODY (also known as MODY3), accounting for 50 to 70 percent of cases, and GCK-MODY (MODY2), accounting for 30 to 50 percent of cases. Less frequent types include HNF4A-MODY (MODY1) and renal cysts and diabetes (RCAD) syndrome (also known as HNF1B-MODY or MODY5), which each account for 5 to 10 percent of cases. At least ten other types have been identified, and these are very rare.

HNF1A-MODY and HNF4A-MODY have similar signs and symptoms that develop slowly over time. Early signs and symptoms in these types are caused by high blood glucose and may include frequent urination (polyuria), excessive thirst (polydipsia), fatigue, blurred vision, weight loss, and recurrent skin infections. Over time uncontrolled high blood glucose can damage small blood vessels in the eyes and kidneys. Damage to the light-sensitive tissue at the back of the eye (the retina) causes a condition known as diabetic retinopathy that can lead to vision loss and eventual blindness. Kidney damage (diabetic nephropathy) can lead to kidney failure and end-stage renal disease (ESRD). While these two types of MODY are very similar, certain features are particular to each type. For example, babies with HNF4A-MODY tend to weigh more than average or have abnormally low blood glucose at birth, even though other signs of the condition do not occur until childhood or young adulthood. People with HNF1A-MODY have a higher-than-average risk of developing noncancerous (benign) liver tumors known as hepatocellular adenomas.

GCK-MODY is a very mild type of the condition. People with this type have slightly elevated blood glucose levels, particularly in the morning before eating (fasting blood glucose). However, affected individuals often have no symptoms related to the disorder, and diabetes-related complications are extremely rare.

RCAD is associated with a combination of diabetes and kidney or urinary tract abnormalities (unrelated to the elevated blood glucose), most commonly fluid-filled sacs (cysts) in the kidneys. However, the signs and symptoms are variable, even within families, and not everyone with RCAD has both features. Affected individuals may have other features unrelated to diabetes, such as abnormalities of the pancreas or liver or a form of arthritis called gout. [from MedlinePlus Genetics]

Approximately 5 to 20% of all patients with neurofibromatosis type I (162200) carry a heterozygous deletion of approximately 1.4 Mb involving the NF1 gene and contiguous genes lying in its flanking regions (Riva et al., 2000; Jenne et al., 2001), which is caused by nonallelic homologous recombination of NF1 repeats A and C (Dorschner et al., 2000). The 'NF1 microdeletion syndrome' is often characterized by a more severe phenotype than that observed in the majority of NF1 patients. In particular, patients with NF1 microdeletion often show variable facial dysmorphism, mental retardation, developmental delay, an excessive number of early-onset neurofibromas (Venturin et al., 2004), and an increased risk for malignant peripheral nerve sheath tumors (De Raedt et al., 2003). [from OMIM]

Darier-White disease (DAR), also known as keratosis follicularis, is an autosomal dominant skin disorder characterized by warty papules and plaques in seborrheic areas (central trunk, flexures, scalp, and forehead), palmoplantar pits, and distinctive nail abnormalities (Sakuntabhai et al., 1999). Onset is usually before the third decade, and penetrance is complete in adults, although expressivity is variable. Involvement may be severe, with widespread itchy malodorous crusted plaques, painful erosions, blistering, and mucosal lesions. Secondary infection is common. Sun, heat, and sweating exacerbate the symptoms. Darier disease never remits, but oral retinoids may reduce hyperkeratosis. Neuropsychiatric abnormalities, including mild mental retardation and epilepsy, have been described in association with Darier disease in a few families (Burge and Wilkinson, 1992); whether this is an association based on pleiotropism of the mutant gene or reflects coincidence is not clear. Histologic findings are (1) mild nonspecific perivascular infiltration in the dermis; (2) dermal villi protruding into the epidermis; (3) suprabasal detachment of the spinal layer leading to the formation of lacunae containing acantholytic cells; (4) in the more superficial epidermis, dyskeratotic round epidermal cells ('corps ronds'), the most distinctive feature; and (5) in the stratum corneum, 'grains' that resemble parakeratotic cells embedded in a hyperkeratotic horny layer. Electron microscopy reveals loss of desmosomal attachments, perinuclear aggregations of keratin filaments, and cytoplasmic vacuolization. Ultrastructural and immunologic studies suggest the disease results from an abnormality in the desmosome-keratin filament complex leading to a breakdown in cell adhesion. [from OMIM]

Maraviroc is a chemokine receptor antagonist that is used in combination with other antiretroviral agents to treat human immunodeficiency virus type 1 (HIV-1) infection. Maraviroc exerts its therapeutic activity by blocking entry of the HIV-1 virus into immune cells—specifically the CD4-expressing T-helper cells, which play a major role in protecting the body from infection—precursor cells, and dendritic cells. HIV-1 infection is classified in two major forms according to the co-receptor it employs to gain entry in to the cell, namely the chemokine receptor 5 (CCR5) or the CXC chemokine receptor 4 (CXCR4). These co-receptors are expressed on different types of cells, and HIV tropism refers to the types of cells and tissues in which the virus infects and replicates. A tropism assay is conducted to determine which co-receptor the HIV-1 virus uses, i.e., whether the virus is CCR5-tropic, CXCR4-tropic, dual tropic (i.e., HIV-1 virus that is able to use both receptors), or mixed tropic (i.e., a mixture of HIV-1 viruses, some of which use CCR5 and others that use CXCR4). Maraviroc is only indicated for treatment of adults with CCR5 tropic HIV-1 and is not recommended when the CXCR4-tropic virus has been detected. The FDA-approved drug label for maraviroc states that “prior to initiation of maraviroc, test all patients for CCR5 tropism using a highly sensitive tropism assay”. [from Medical Genetics Summaries]

MN antigens reside on GYPA, one of the most abundant red-cell glycoproteins. The M and N antigens are 2 autosomal codominant antigens encoded by the first 5 amino acids of GYPA and include 3 O-linked glycans as part of the epitope. M and N differ at amino acids 1 and 5, where M is ser-ser-thr-thr-gly, and N is leu-ser-thr-thr-glu. M is the ancestral GYPA allele and is common in all human populations and Old World apes. GYPA, glycophorin B (GYPB; 617923), and glycophorin E (GYPE; 138590) are closely linked on chromosome 4q31. The N terminus of GYPB is essentially identical to that of GYPA except that it always expresses the N antigen, denoted 'N' or N-prime. Antigens of the Ss blood group (111740) reside on GYPB, and recombination and gene conversion between GYPA, GYPB, and GYPE lead to hybrid glycophorin molecules and generation of low-incidence antigens. Thus, the MN and Ss blood groups are together referred to as the MNSs or MNS blood group system. The U antigen refers to a short extracellular sequence in GYPB located near the membrane. Recombination results in 3 glycophorin-null phenotypes: En(a-) cells lack GYPA due to recombination between GYPA and GYPB; GYPB-negative (S-s-U-) cells lack GYPB due to recombination in GYPB; and M(k) cells (M-N-S-s-U-) lack both GYPA and GYPB due to recombination between GYPA and GYPE. Individuals with glycophorin-null phenotypes have decreased sialic acid content and increased resistance to malarial infection (see 611162). GYPA and GYPB are not essential for red-cell development or survival, and GYPA- and GYPB-null phenotypes are not associated with anemia or altered red-cell function (review by Cooling, 2015). [from OMIM]

Nonmedullary thyroid cancer (NMTC) comprises thyroid cancers of follicular cell origin and accounts for more than 95% of all thyroid cancer cases. The remaining cancers originate from parafollicular cells (medullary thyroid cancer, MTC; 155240). NMTC is classified into 4 groups: papillary, follicular, Hurthle cell (607464), and anaplastic. Approximately 5% of NMTC is hereditary, occurring as a minor component of a familial cancer syndrome (e.g., familial adenomatous polyposis, 175100, Carney complex, 160980) or as a primary feature (familial NMTC or FNMTC). Papillary thyroid cancer (PTC) is the most common histologic subtype of FNMTC, accounting for approximately 85% of cases (summary by Vriens et al., 2009). Follicular thyroid cancer (FTC) accounts for approximately 15% of NMTC and is defined by invasive features that result in infiltration of blood vessels and/or full penetration of the tumor capsule, in the absence of the nuclear alterations that characterize papillary carcinoma. FTC is rarely multifocal and usually does not metastasize to the regional lymph nodes but tends to spread via the bloodstream to the lung and bones. An important histologic variant of FTC is the oncocytic (Hurthle cell, oxyphilic) follicular carcinoma composed of eosinophilic cells replete with mitochondria (summary by Bonora et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of NMTC, see NMTC1 (188550). [from OMIM]

Hereditary angioedema is a disorder characterized by recurrent episodes of severe swelling (angioedema). The parts of the body that are most often affected by swelling are the limbs, face, intestinal tract, and airway. Minor trauma or stress may trigger an attack, but swelling often occurs without a known trigger. Episodes involving the intestinal tract cause severe abdominal pain, nausea, and vomiting. Swelling in the airway can restrict breathing and lead to life-threatening obstruction of the airway. About one-third of people with this condition develop a non-itchy rash called erythema marginatum during an attack.

Symptoms of hereditary angioedema typically begin in childhood and worsen during puberty.  On average, untreated individuals have swelling episodes every 1 to 2 weeks, and most episodes last for about 3 to 4 days. The frequency and duration of attacks vary greatly among people with hereditary angioedema, even among people in the same family.

Hereditary angioedema is broadly divided into two types, which are distinguished by levels of a protein called C1 inhibitor (C1-INH) in the blood. These types are known as hereditary angioedema due to C1-INH deficiency and hereditary angioedema with normal C1-INH. 



Hereditary angioedema due to C1-INH deficiency is further divided into two types: type I occurs when C1-INH levels are low, and type II occurs when the C1-INH protein is not functioning correctly. 

The different types of hereditary angioedema have similar signs and symptoms.  [from MedlinePlus Genetics]

Azoospermia, a condition in which there are no sperm present in the ejaculate, has historically been divided into 2 broad categories, obstructive (e.g., 277180) and nonobstructive. Among the genetically based, inherited nonobstructive causes are defects of spermatogenesis, which may interrupt the development of the sperm at various stages, either before (e.g., 415000) or during meiosis. SPGF4 is a form of azoospermia due to perturbations of meiosis. For a discussion of phenotypic and genetic heterogeneity of spermatogenic failure, see SPGF1 (258150). Recurrent Pregnancy Loss Miscarriage, the commonest complication of pregnancy, is the spontaneous loss of a pregnancy before the fetus has reached viability. The term therefore includes all pregnancy losses from the time of conception until 24 weeks' gestation. Recurrent miscarriage, defined as 3 or more consecutive pregnancy losses, affects about 1% of couples; when defined as 2 or more losses, the scale of the problem increases to 5% of all couples trying to conceive (summary by Rai and Regan, 2006). Pregnancy losses have traditionally been designated 'spontaneous abortions' if they occur before 20 weeks' gestation and 'stillbirths' if they occur after 20 weeks. Subtypes of spontaneous abortions can be further distinguished on the basis of embryonic development and include anembryonic loss in the first 5 weeks after conception (so-called 'blighted ovum'), embryonic loss from 6 to 9 weeks' gestation, and fetal loss from 10 weeks' gestation through the remainder of the pregnancy. These distinctions are important because the causes of pregnancy loss vary over gestational ages, with anembryonic losses being more likely to be associated with chromosomal abnormalities, for example. Possible etiologies for recurrent pregnancy loss include uterine anatomic abnormalities, cytogenetic abnormalities in the parents or fetus, single gene disorders, thrombophilic conditions, and immunologic or endocrine factors as well as environmental or infectious agents (summary by Warren and Silver, 2008). For a discussion of genetic heterogeneity of recurrent pregnancy loss, see RPRGL1 (614389). [from OMIM]