An autoimmune form of hemolytic anemia.

A large brown, blue, or gray hamartoma of dermal melanocytes, usually on the shoulder and upper arm that is most commonly found in Asian populations and in females. It is sometimes associated with sensory changes in the involved skin area, but very rarely becomes cancerous.

Polycystic ovary syndrome is a condition that affects women in their child-bearing years and alters the levels of multiple hormones, resulting in problems affecting many body systems.\n\nMost women with polycystic ovary syndrome produce excess male sex hormones (androgens), a condition called hyperandrogenism. Having too much of these hormones typically leads to excessive body hair growth (hirsutism), acne, and male pattern baldness.\n\nHyperandrogenism and abnormal levels of other sex hormones prevent normal release of egg cells from the ovaries (ovulation) and regular menstrual periods, leading to difficulty conceiving a child (subfertility) or a complete inability to conceive (infertility). For those who achieve pregnancy, there is an increased risk of complications and pregnancy loss. Due to irregular and infrequent menstruation and hormone abnormalities, affected women have an increased risk of cancer of the uterine lining (endometrial cancer).\n\nIn polycystic ovary syndrome, one or both ovaries can contain multiple small, immature ovarian follicles that can appear as cysts on medical imaging. Normally, ovarian follicles contain egg cells, which are released during ovulation. In polycystic ovary syndrome, abnormal hormone levels prevent follicles from growing and maturing to release egg cells. Instead, these immature follicles accumulate in the ovaries. Affected women can have 12 or more of these follicles. The number of these follicles usually decreases with age.\n\nAbout half of all women with polycystic ovary syndrome are overweight or have obesity and are at increased risk of a fatty liver. Additionally, many women with polycystic ovary syndrome have elevated levels of insulin, which is a hormone that helps control levels of blood glucose, also called blood sugar. By age 40, about 10 percent of overweight women with polycystic ovary syndrome develop abnormally high blood glucose levels (type 2 diabetes), and up to 35 percent develop prediabetes (higher-than-normal blood glucose levels that do not reach the cutoff for diabetes). Obesity and increased insulin levels (hyperinsulinemia) further increase the production of androgens in polycystic ovary syndrome.\n\nWomen with polycystic ovary syndrome are also at increased risk for developing metabolic syndrome, which is a group of conditions that include high blood pressure (hypertension), increased belly fat, high levels of unhealthy fats and low levels of healthy fats in the blood, and high blood glucose levels. About 20 percent of affected adults experience pauses in breathing during sleep (sleep apnea). Women with polycystic ovary syndrome are more likely than women in the general popluation to have mood disorders such as depression.

Abnormally low concentrations of vitamin C in the blood.

The presence of a gonadoblastoma, a neoplasm of a gonad that consists of aggregates of germ cells and sex cord elements.

Interstitial lung disease (ILD), or pneumonitis, is a heterogeneous group of disorders characterized pathologically by expansion of the interstitial compartment of the lung by inflammatory cells. Fibrosis occurs in many cases (Visscher and Myers, 2006). See also interstitial lung disease-1 (ILD1; 619611). Desquamative interstitial pneumonitis (DIP) was originally described as a pathologic entity by Liebow et al. (1965). Lung biopsy shows diffuse and uniform filling of alveoli by clusters of cells which Liebow et al. (1965) speculated to be 'desquamated pneumocytes.' Since then, these cells have been shown primarily to be pigmented alveolar macrophages. Other features include thickened alveolar septa with an infiltrate of inflammatory cells and plump, cuboidal type II pneumocytes. Mild collagen deposition without architectural distortion or honeycombing may be present. Different forms of ILD represent pathologic classifications based on histologic patterns rather than clinical diagnoses and may occur in a variety of clinical contexts (Visscher and Myers, 2006). Although DIP occurs most often as a sporadic disorder in adults during the third to fifth decade of life and is highly associated with smoking (Carrington et al., 1978), reports of a familial form with onset in infancy and early death suggest a genetic basis (Sharief et al., 1994). Cases of DIP reported in infants are often more severe and refractory to treatment than those reported in adults (Nogee et al., 2001).

FLNA deficiency is associated with a phenotypic spectrum that includes FLNA-related periventricular nodular heterotopia (Huttenlocher syndrome), congenital heart disease (patent ductus arteriosus, atrial and ventricular septal defects), valvular dystrophy, dilation and rupture of the thoracic aortic, pulmonary disease (pulmonary hypertension, alveolar hypoplasia, emphysema, asthma, chronic bronchitis), gastrointestinal dysmotility and obstruction, joint hypermobility, and macrothrombocytopenia.

PAFAH1B1-related lissencephaly/subcortical band heterotopia (SBH) comprises a spectrum of severity. Affected newborns typically have mild-to-moderate hypotonia, feeding difficulties, and poor head control. During the first years, neurologic examination typically demonstrates poor visual tracking and response to sounds, axial hypotonia, and mild distal spasticity that can transition over time to more severe spasticity. Seizures occur in more than 90% of individuals with lissencephaly and often include infantile spasms. Seizures are often drug resistant, but even with good seizure control, the best developmental level achieved (excluding the few individuals with partial lissencephaly) is the equivalent of about age three to five months. In individuals with PAFAH1B1-related lissencephaly/SBH, developmental delay ranges from mild to severe. Other findings in PAFAH1B1-related lissencephaly/SBH include feeding issues and aspiration (which may result in need for gastrostomy tube placement), progressive microcephaly, and occasional developmental regression.

African iron overload is a distinct iron-loading disorder prevalent in Africa. Formerly termed Bantu siderosis, the disorder results from a predisposition to iron loading that is exacerbated by excessive intake of dietary iron. It is particularly a problem among Africans who drink a traditional beer brewed in non-galvanized steel drums. Although the disorder was once attributed to dietary excess alone, serious iron overload does not develop in all beer drinkers, and not all patients with iron overload consume excessive amounts of the beer (summary by Andrews, 1999).

Xanthinuria, which was first described by Dent and Philpot (1954), is characterized by excretion of large amounts of xanthine in the urine and a tendency to form xanthine stones. Uric acid is strikingly diminished in serum and urine. Two clinically similar but distinct forms of xanthinuria are recognized. In type I there is an isolated deficiency of xanthine dehydrogenase, and in type II (XAN2; 603592) there is a dual deficiency of xanthine dehydrogenase and aldehyde oxidase (603592). Type I patients can metabolize allopurinol, whereas type II patients cannot (Simmonds et al., 1995). Xanthinuria also occurs in molybdenum cofactor deficiency (252150). Type II xanthinuria is caused by mutation in the MOCOS gene (613274), which encodes the enzyme that sulfurates the molybdenum cofactor for XDH and AOX1 (602841).

Aspartylglucosaminuria (AGU) is a severe autosomal recessive lysosomal storage disorder that involves the central nervous system and causes skeletal abnormalities as well as connective tissue lesions. The most characteristic feature is progressive mental retardation. The disorder is caused by deficient activity of the lysosomal enzyme glycosylasparaginase, which results in body fluid and tissue accumulation of a series of glycoasparagines, i.e., glycoconjugates with an aspartylglucosamine moiety at the reducing end. AGU belongs to the group of disorders commonly referred to as the Finnish disease heritage (summary by Mononen et al., 1993 and Arvio and Arvio, 2002).

HSD17B3 deficiency is an autosomal recessive disorder that manifests, in males, as undermasculinization characterized by hypoplastic-to-normal internal genitalia (epididymis, vas deferens, seminal vesicles, and ejaculatory ducts) but female external genitalia and the absence of a prostate. This phenotype is caused by inadequate testicular synthesis of testosterone, which, in turn, results in insufficient formation of dihydrotestosterone in the anlage of the external genitalia and prostate during fetal development. At the expected time of puberty, there is a marked increase in plasma leuteinizing hormone and, consequently, in testicular secretion of androstenedione. Hence, a diagnostic hallmark of this disorder is a decreased plasma testosterone-to-androstenedione ratio. Significant amounts of the circulating androstenedione are, however, converted to testosterone, in peripheral tissues, thereby causing virilization (summary by Lindqvist et al., 2001).

Pseudovaginal perineoscrotal hypospadias is a form of male pseudohermaphroditism in which 46,XY males show ambiguous genitalia at birth, including perineal hypospadias and a blind perineal pouch, and develop masculinization at puberty. The name of the disorder stems from the finding of a blind-ending perineal opening resembling a vagina and a severely hypospadiac penis with the urethra opening onto the perineum.

Aland Island eye disease (AIED) is an X-linked recessive retinal disease characterized by fundus hypopigmentation, decreased visual acuity, nystagmus, astigmatism, protan color vision defect (303900), progressive myopia, and defective dark adaptation. Although AIED has been referred to as a form of albinism, there is no misrouting of the optic nerves, which excludes it from the formal diagnosis of classic albinism (King et al., 2001).

A disorder that is characterized by increased glutathione concentration in the plasma and urine.

A type of central congenital hypothyroidism, a permanent thyroid deficiency that is present from birth, characterized by low levels of thyroid hormones due to a deficiency in TSH synthesis.

A rare inflammatory and suppurating type of tinea capitis, a skin infection caused by <i>Trichophyton</i> or <i>Microsporum</i> fungi, that predominantly affects the scalp and that is characterized by the development of painful crusty lesions covered with follicular pustules and surrounded by erythematous alopecic areas, that can later evolve into abscesses and leave permanent cicatricial alopecia. Lesions can be associated with regional lymphadenopathy.

Signs and symptoms of congenital hypothyroidism result from the shortage of thyroid hormones. Affected babies may show no features of the condition, although some babies with congenital hypothyroidism are less active and sleep more than normal. They may have difficulty feeding and experience constipation. If untreated, congenital hypothyroidism can lead to intellectual disability and slow growth. In the United States and many other countries, all hospitals test newborns for congenital hypothyroidism. If treatment begins in the first two weeks after birth, infants usually develop normally.\n\nCongenital hypothyroidism occurs when the thyroid gland fails to develop or function properly. In 80 to 85 percent of cases, the thyroid gland is absent, severely reduced in size (hypoplastic), or abnormally located. These cases are classified as thyroid dysgenesis. In the remainder of cases, a normal-sized or enlarged thyroid gland (goiter) is present, but production of thyroid hormones is decreased or absent. Most of these cases occur when one of several steps in the hormone synthesis process is impaired; these cases are classified as thyroid dyshormonogenesis. Less commonly, reduction or absence of thyroid hormone production is caused by impaired stimulation of the production process (which is normally done by a structure at the base of the brain called the pituitary gland), even though the process itself is unimpaired. These cases are classified as central (or pituitary) hypothyroidism.\n\nCongenital hypothyroidism can also occur as part of syndromes that affect other organs and tissues in the body. These forms of the condition are described as syndromic. Some common forms of syndromic hypothyroidism include Pendred syndrome, Bamforth-Lazarus syndrome, and brain-lung-thyroid syndrome.\n\nCongenital hypothyroidism is a partial or complete loss of function of the thyroid gland (hypothyroidism) that affects infants from birth (congenital). The thyroid gland is a butterfly-shaped tissue in the lower neck. It makes iodine-containing hormones that play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism). People with congenital hypothyroidism have lower-than-normal levels of these important hormones.

Severely reduced physical and mental growth associated with pyramidal and extrapyramidal signs and symptoms, due to dietary iodine deficiency.

A rare, genetic, benign disorder of cobalamin transport, due to variable degrees of transcobalamin I deficiency, characterized by mildly low to almost undetectable plasma transcobalamin I levels and slighly low to absent serum cobalamin levels. Normal methylmalonic acid and homocysteine serum values and absence of megaloblastic anemia are reported. No specific clinical manifestations are associated and patients are typically asymptomatic.

The thiopurines include azathioprine (a pro-drug for mercaptopurine), mercaptopurine and thioguanine. They are used to treat a variety of immunological disorders such as rheumatoid arthritis, non- Hodgkin lymphoma and ulcerative colitis. Both mercaptopurine and thioguanine can exert cytotoxic effects through the formation of thioguanine nucleotides (TGNs), active metabolites that incorporate into DNA. Mercaptopurine and thioguanine are directly inactivated by thiopurine S-methyltransferase (TPMT). Individuals with two nonfunctional TPMT alleles are at 100% risk of potentially fatal myelosuppression, due to an increased buildup of toxic TGNs. Alternative agents or a drastically reduced dose are recommended for patients with this genotype. Patients heterozygous for a nonfunctional TPMT allele are at increased risk of myelosuppression, and reduced dosing is recommended for these individuals. These dosing guidelines have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website.

Congenital disorders of glycosylation (CDGs) are divided into 2 main groups: type I CDGs (see, e.g., 212065) comprise defects in the assembly of the dolichol lipid-linked oligosaccharide (LLO) chain and its transfer to the nascent protein, whereas type II CDGs (see, e.g., 212066) refer to defects in the trimming and processing of the protein-bound glycans either late in the endoplasmic reticulum or the Golgi compartments. Conventionally, untyped and unclassified cases are labeled 'CDG-x' (Orlean, 2000; Marquardt and Denecke, 2003). The phenotypes described in this entry most likely do not represent a single disorder, but have been referred by the authors as CDG-x and are included here pending further molecular characterization. In a review of CDGs, Marquardt and Denecke (2003) stated that more than 20% of CDG patients identified still cannot be ascribed to a known enzyme defect and are thus named CDG-x.

A rare primary immunodeficiency due to a defect in innate immunity characterized by a marked decrease or absence of myeloperoxidase activity in neutrophils and monocytes. Clinically, most patients are asymptomatic. Occasionally, severe infectious complications may occur, particularly recurrent candida infections, being especially severe in the setting of comorbid diabetes mellitus.

Congenital disorder of glycosylation type IIc (CDG2C) is an autosomal recessive disorder characterized by moderate to severe psychomotor retardation, mild dysmorphism, and impaired neutrophil motility. It is a member of a group of disorders with a defect in the processing of protein-bound glycans. For a general overview of congenital disorders of glycosylation (CDGs), see CDG1A (212065) and CDG2A (212066). Frydman (1996) contended that the neutrophil defect in CDG2C, which has been referred to as 'leukocyte adhesion deficiency type II' (LAD2), is a manifestation of the disorder and that there are no cases of 'primary' LAD II. Etzioni and Harlan (1999) provided a comprehensive review of both leukocyte adhesion deficiency-1 (LAD1; 116920) and LAD2. While the functional neutrophil studies are similar in the 2 LADs, the clinical course is milder in LAD2. Furthermore, patients with LAD2 present other abnormal features, such as growth and mental retardation, which are related to the primary defect in fucose metabolism. Delayed separation of the umbilical cord occurs in LAD1. For a discussion of genetic heterogeneity of LAD, see 116920.

An autosomal recessive condition caused by mutation(s) in the CPN1 gene, encoding carboxypeptidase N catalytic chain. It may be characterized by episodic angioedema, chronic urticaria, asthma and/or allergic hypersensitivity.

GAPO syndrome is the acronymic designation for a complex of growth retardation, alopecia, pseudoanodontia (failure of tooth eruption), and progressive optic atrophy (Tipton and Gorlin, 1984). Ilker et al. (1999) and Bayram et al. (2014) noted that optic atrophy is not a consistent feature of the disorder.

Spinocerebellar ataxia type 2 (SCA2) is characterized by progressive cerebellar ataxia, including nystagmus, slow saccadic eye movements, and in some individuals, ophthalmoparesis or parkinsonism. Pyramidal findings are present; deep tendon reflexes are brisk early on and absent later in the course. Age of onset is typically in the fourth decade with a ten- to 15-year disease duration.

Free sialic acid storage disorders (FSASDs) are a spectrum of neurodegenerative disorders resulting from increased lysosomal storage of free sialic acid. Historically, FSASD was divided into separate allelic disorders: Salla disease, intermediate severe Salla disease, and infantile free sialic acid storage disease (ISSD). The mildest type was Salla disease, characterized by normal appearance and absence of neurologic findings at birth, followed by slowly progressive neurologic deterioration resulting in mild-to-moderate psychomotor delays, spasticity, athetosis, and epileptic seizures. Salla disease was named for a municipality in Finnish Lapland where a specific founder variant is relatively prevalent. However, the term Salla has been used in the literature to refer to less severe FSASD. More severe FSASD is historically referred to as ISSD, and is characterized by severe developmental delay, coarse facial features, hepatosplenomegaly, and cardiomegaly; death usually occurs in early childhood.

Ribose-5-P isomerase deficiency is an extremely rare, hereditary, disorder of pentose phosphate metabolism characterized by progressive leukoencephalopathy and a highly increased ribitol and D-arabitol levels in the brain and body fluids. Clinical presentation includes psychomotor delay, epilepsy, and childhood-onset slow neurological regression with ataxia, spasticity, optic atrophy and sensorimotor neuropathy.

Sjogren syndrome is an autoimmune disease that mainly affects the exocrine glands. It is clinically characterized by keratoconjunctivitis sicca and xerostomia (Goransson et al., 2006). See 200400 for association of Sjogren syndrome with achalasia in sisters.

Macular corneal dystrophy (MCD) is an autosomal recessive disorder in which progressive punctate opacities in the cornea result in bilateral loss of vision, eventually necessitating corneal transplantation. MCD is classified into 2 subtypes, type I and type II, defined by the respective absence and presence of sulfated keratan sulfate in the patient serum, although both types have clinically indistinguishable phenotypes (summary by Akama et al., 2000).

A chronic adhesive arachnoiditis in the spinal arachnoid, with root and spinal cord symptoms similar to those caused by pressure from a tumor.

This syndrome has characteristics of short stature presenting in the neonatal period, associated with osteochondrodysplastic lesions and facial dysmorphism. It has been described in two members from the same family.

A rare hyperthyroidism characterized by mild to severe hyperthyroidism, presence of goiter, absence of features of autoimmunity, frequent relapses while on treatment and a positive family history.

Emanuel syndrome is characterized by pre- and postnatal growth deficiency, microcephaly, hypotonia, severe developmental delays, ear anomalies, preauricular tags or pits, cleft or high-arched palate, congenital heart defects, kidney abnormalities, and genital abnormalities in males.

AICA-ribosuria is characterized by severe to profound global neurodevelopmental impairment, severe visual impairment due to chorioretinal atrophy, ante-postnatal growth impairment, and severe scoliosis. Dysmorphic features include coarse facies and upturned nose. Early-onset epilepsy may occur. Less common features may include aortic coarctation, chronic hepatic cytolysis, minor genital malformations, and nephrocalcinosis (Ramond et al., 2020).

This syndrome is characterized by osteopetrosis, agenesis of the corpus callosum, cerebral atrophy and a small hippocampus.

Properdin (factor P) is a plasma protein that is active in the alternative complement pathway of the innate immune system. It is a positive regulatory factor that binds to many microbial surfaces to stabilize the C3b,Bb convertase. Deficiency of properdin is associated in particular with a heightened susceptibility to Neisseria species (Janeway et al., 2001).

Any azoospermia in which the cause of the disease is a mutation in the TEX11 gene.

Glomuvenous malformations, also known as 'venous malformations with glomus cells' or glomangiomas, are similar to mucocutaneous venous malformations (VMCM; 600195), but clinically are distinguishable: they have a cobble-stone appearance, have a consistency harder than that of venous malformations, and are painful on palpation. Histologically, GVMs are distinguishable by the presence of pathognomonic rounded cells (glomus cells) around the distended vein-like channels. The term glomus (Latin for ball) stems from the morphologically similar contractile cells of the Sucquet-Hoyer arteriovenous anastomoses in glomus bodies that are involved in cutaneous thermoregulation. Glomus cells in GVMs appear to be incompletely or improperly differentiated vascular smooth muscle cells, since they stain positively with smooth muscle cell alpha-actin (102620) and vimentin (193060) (summary by Brouillard et al., 2002). The genetic distinctness of glomuvenous malformations from mucocutaneous venous malformations is indicated by the fact that mutations have been found in the TIE2/TEK gene (600221) in mucocutaneous venous malformations and not in glomuvenous malformations.

Autosomal dominant limb-girdle muscular dystrophy-2 (LGMDD2) is a myopathy characterized by proximal muscle weakness primarily affecting the lower limbs, but also affecting the upper limbs in most patients. Affected individuals also have distal muscle weakness of the hands and lower leg muscles. There is variability in presentation and progression. Some patients present in early childhood with mildly delayed walking and difficulty running and jumping, whereas others present as adults with mainly pelvic-girdle weakness. Patients with early onset tend to have a more severe disorder, and may develop contractures, loss of independent ambulation, and respiratory insufficiency. Muscle biopsy shows dystrophic changes with abnormal nuclei, rimmed vacuoles, and filamentous inclusions (summary by Melia et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of autosomal dominant limb-girdle muscular dystrophy, see LGMDD1 (603511).

Habib et al. (1973) recognized 2 morphologic classes for the glomerular changes seen in patients with mesangiocapillary (membranoproliferative) glomerulonephritis (MPGN). Type I is characterized by double contour appearance of the capillary walls due to mesangial cell interposition, with nonargyrophilic subendothelial deposits which are finely granular on electron microscopy. Type II is characterized by linear dense deposits within the basement membrane and only rare double contours. These 2 types appear to be distinct with no conversion of one type to another on serial biopsy. Strife et al. (1977) described a third variety in which there are not only subendothelial deposits but also numerous subepithelial and intramembranous deposits, associated with replication of the lamina densa and frequently disruption of the whole basement membrane.

Fingerprint body myopathy is a congenital benign muscle disorder characterised by congenital hypotonia and weakness and by the presence of numerous fingerprint bodies located at the periphery of the muscle fibers. Prevalence is unknown. Less than 20 patients have been described. Few sporadic cases have been observed, as well as cases of recessive transmission.

X-linked infantile spinal muscular atrophy (XL-SMA) is characterized by congenital hypotonia, areflexia, and evidence of degeneration and loss of anterior horn cells (i.e., lower motor neurons) in the spinal cord and brain stem. Often congenital contractures and/or fractures are present. Intellect is normal. Life span is significantly shortened because of progressive ventilatory insufficiency resulting from chest muscle involvement.

X-linked sideroblastic anemia and ataxia is a rare condition characterized by a blood disorder called sideroblastic anemia and movement problems known as ataxia. This condition occurs only in males.\n\nSideroblastic anemia results when developing red blood cells called erythroblasts do not make enough hemoglobin, which is the protein that carries oxygen in the blood. People with X-linked sideroblastic anemia and ataxia have mature red blood cells that are smaller than normal (microcytic) and appear pale (hypochromic) because of the shortage of hemoglobin. This disorder also leads to an abnormal accumulation of iron in red blood cells. The iron-loaded erythroblasts, which are present in bone marrow, are called ring sideroblasts. These abnormal cells give the condition its name. Unlike other forms of sideroblastic anemia, X-linked sideroblastic anemia and ataxia does not cause a potentially dangerous buildup of iron in the body. The anemia is typically mild and usually does not cause any symptoms.\n\nX-linked sideroblastic anemia and ataxia causes problems with balance and coordination that appear early in life. The ataxia primarily affects the trunk, making it difficult to sit, stand, and walk unassisted. In addition to ataxia, people with this condition often have trouble coordinating movements that involve judging distance or scale (dysmetria) and find it difficult to make rapid, alternating movements (dysdiadochokinesis). Mild speech difficulties (dysarthria), tremor, and abnormal eye movements have also been reported in some affected individuals.

An extremely rare autosomal recessively inherited neuromuscular disease characterised by ocular manifestations such as ptosis and diplopia followed by chronic diarrhoea, malnutrition and intestinal pseudo-obstruction.

This syndrome has characteristics of intrauterine growth retardation, renal dysgenesis and a unilobed or absent thymus. It has been described in three girls born to a nonconsanguineous couple.

Progesterone prepares the endometrium for blastocyst implantation and allows maintenance of pregnancy. The major sources of progesterone are the corpus luteum during the second half of the menstrual cycle and at the beginning of pregnancy, and the placenta. The main hormones responsible for stimulation of progesterone secretion are luteinizing hormone (LH) for the corpus luteum of the menstrual cycle and chorionic gonadotropin for the corpus luteum of pregnancy. Complete end-organ resistance to progesterone would be incompatible with reproductive competence in females. Males would not be expected to be affected since progesterone has no known function in men. Failure of the uterus to respond to progesterone would lead to the development of a 'constantly proliferative' endometrium incompatible with blastocyst implantation. Partial resistance to progesterone, on the other hand, would be expected to be associated with various degrees of incomplete maturation of the endometrium, perhaps expressed clinically as infertility or early abortions. The syndrome would present with the clinical and histologic picture of a luteal phase defect in which the life span of the corpus luteum and the plasma progesterone concentrations would be normal or elevated.

Kowarski syndrome, or short stature associated with bioinactive growth hormone, is characterized clinically by normal or slightly increased GH secretion, pathologically low IGF1 (147440) levels, and normal catch-up growth on GH replacement therapy (Besson et al., 2005).

A rare multiple congenital anomalies/dysmorphic syndrome with characteristics of profound intellectual disability, choreoathetosis, progressive spastic diplegia, progressive tapetoretinal degeneration with loss of retinal vessels and glomerulopathy resulting in death late in the first or early in the second decade of life. Absence of the cerebellar granular layer has been reported.

This disease has characteristics of retinitis pigmentosa, trichodysplasia, dental anomalies, and onychodysplasia. It has been described in two siblings (brother and sister) born to first cousin parents. Transmission appears to be autosomal recessive.

Neutrophil actin dysfunction (NAD) is an immunologic disorder characterized by early onset of recurrent infections, including oral, skin, and respiratory. Organisms are mainly bacterial and fungal. Patients tend to develop fever and hepatosplenomegaly with continued infection; bone marrow transplant is an effective treatment. The disorder results from impaired neutrophil mobility and chemotaxis associated with abnormal actin dynamics. Although a causative mutation has not been identified, studies have shown an association between the disorder and increased levels of a 47-kD F-actin-binding protein known as LSP1 (153432) and decreased levels of an unknown 89-kD protein (summary by Coates et al., 1991 and Howard et al., 1998).

The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The lipopigment pattern seen most often in CLN1 is referred to as granular osmiophilic deposits (GROD). The patterns most often observed in CLN2 and CLN3 are 'curvilinear' and 'fingerprint' profiles, respectively. CLN4, CLN5, CLN6, CLN7, and CLN8 show mixed combinations of granular, curvilinear, fingerprint, and rectilinear profiles. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). Zeman and Dyken (1969) referred to these conditions as the 'neuronal ceroid lipofuscinoses.' Goebel (1995) provided a comprehensive review of the NCLs and noted that they are possibly the most common group of neurodegenerative diseases in children. Mole et al. (2005) provided a detailed clinical and genetic review of the neuronal ceroid lipofuscinoses. Genetic Heterogeneity of Neuronal Ceroid Lipofuscinosis See also CLN2 (204500), caused by mutation in the TPP1 gene (607998) on chromosome 11p15; CLN3 (204200), caused by mutation in the CLN3 gene (607042) on 16p12; CLN4 (162350), caused by mutation in the DNAJC5 gene (611203) on 20q13; CLN5 (256731), caused by mutation in the CLN5 gene (608102) on 13q22; CLN6A (601780) and CLN6B (204300), both caused by mutation in the CLN6 gene (606725) on 15q21; CLN7 (610951), caused by mutation in the MFSD8 gene (611124) on 4q28; CLN8 (600143) and the Northern epilepsy variant of CLN8 (610003), both caused by mutation in the CLN8 gene (607837) on 8p23; CLN10 (610127), caused by mutation in the CTSD gene (116840) on 11p15; CLN11 (614706), caused by mutation in the GRN gene (138945) on 17q21; CLN13 (615362), caused by mutation in the CTSF gene (603539) on 11q13; and CLN14 (611726), caused by mutation in the KCTD7 gene (611725) on 7q11. CLN9 (609055) has not been molecularly characterized. A disorder that was formerly designated neuronal ceroid lipofuscinosis-12 (CLN12) is now considered to be a variable form of Kufor-Rakeb syndrome (KRS; 606693).

A rare congenital myopathy syndrome characterized by nonprogressive myopathy (manifesting with mild facial and generalized weakness, bilateral ptosis, and severe lumbar lordosis), severe intellectual disability, short stature, and sexual infantilism (due to hypogonadotropic hypogonadism). The presence of a small pituitary fossa was also noted. There have been no further descriptions in the literature since 1985.

A rare developmental defect with connective tissue involvement characterized by multiple joint dislocations, flattened facial appearance, abnormal palmar creases, laryngotracheomalacia, and pulmonary hypoplasia. Additional signs may include a bifid tongue, micrognathia, non-immune hydrops fetalis, and brain dysplasia. The disease is lethal shortly after birth due to respiratory insufficiency.

Hypermetabolism due to uncoupled mitochondrial oxidative phosphorylation-1 (HUMOP1) is characterized by an increased basal metabolic rate (BMR) manifest as increased sweating, polyphagia with poor weight gain, increased basal temperature, tachycardia, and tachypnea. Some patients may have mild muscle weakness. Skeletal muscle biopsy shows enlarged irregular mitochondria with proliferation of the cristae and inclusions. Biochemical studies show excessive oxygen consumption and mitochondrial respiratory activity that is loosely coupled or uncoupled to phosphorylation of ADP to ATP (summary by Haydar et al., 1971). See also HUMOP2 (620085), caused by mutation in the ATP5F1B gene (102910) on chromosome 12q13.

Gamma-glutamylcysteine synthetase deficiency is 1 of 4 diseases involving enzymes in the gamma-glutamyl cycle (Meister, 1974). The other 3 disorders are glutathione synthetase deficiency (231900), 5-oxoprolinuria, which is a severe or generalized form of glutathione synthetase deficiency (266130), and gamma-glutamyl transpeptidase deficiency (231950). All except gamma-glutamyl transpeptidase deficiency are accompanied by hemolytic anemia (Larsson and Anderson, 2001).

A rare, genetic, epilepsy syndrome characterized by epilepsy, palpebral conjunctival telangiectasias, borderline to moderate intellectual disability, diminished serum IgA levels, shortened fifth fingers and dysmorphic facial features (including frontal hirsutism, synophrys, anteverted nostrils, prominent ears, long philtrum, irregular teeth implantation, micrognathia). No new cases have been described in the literature since 1978.

The proliferative vasculopathy and hydranencephaly-hydrocephaly syndrome is a rare, autosomal recessive, usually prenatally lethal disorder characterized by hydranencephaly, a distinctive glomerular vasculopathy in the central nervous system and retina, and diffuse ischemic lesions of the brain stem, basal ganglia, and spinal cord with calcifications. It is usually diagnosed by ultrasound between 26 and 33 weeks' gestation (summary by Meyer et al., 2010). Rarely, affected individuals may survive, but are severely impaired with almost no neurologic development (Kvarnung et al., 2016).

Ectodermal dysplasia-intellectual disability-central nervous system malformation syndrome is a rare, multiple developmental anomalies syndrome characterized by the triad of ectodermal dysplasia (mostly hypohidrotic with dry skin and reduced sweating and sparse, fair scalp hair, eyebrows and eyelashes), severe intellectual disability and variable central nervous system anomalies (cerebellar hypoplasia, dilatation of ventricles, corpus callosum agenesis, Dandy-Walker malformation). Distinct craniofacial dysmorphism with macrocephaly, frontal bossing, midfacial hypoplasia and high arched or cleft palate, as well as cryptorchidism, feeding difficulties and hypotonia, are associated. There have been no further descriptions in the literature since 1998.

This syndrome is characterized by the association of a progressive leukodystrophy marked by generalized mental and motor impairment with the presence of thickened and wrinkled skin. It has been described in a Japanese brother and sister born to healthy parents. Both patients died in early childhood.

A group of congenital cardiac outflow tract anomalies that include such defects as tetralogy of Fallot, pulmonary atresia with ventricular septal defect, double-outlet right ventricle (DORV), double-outlet left ventricle, truncus arteriosus and transposition of the great arteries (TGA), among others. This group of defects is frequently found in patients with 22q11.2 deletion syndrome . A deletion of chromosome 22q11.2 has equally been associated in a subset of patients with various types of isolated non-syndromic conotruncal heart malformations (with the exception of DORV and TGA where this is very uncommon).

Familial reactive perforating collagenosis is a very rare genetic skin disease characterized by transepidermal elimination of collagen fibers presenting as recurrent spontaneously involuting keratotic papules or nodules.

This syndrome has characteristics of intellectual deficit, calcification of the choroid plexus and elevated levels of cerebrospinal fluid protein. It has been described in two sibships from two unrelated families. The seven children of one of the sibships were born to consanguineous parents. Some patients also had strabismus, hyperactive deep tendon reflexes and foot deformities.

PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism (delayed puberty and lack of secondary sex characteristics). The hypogonadotropic hypogonadism occurs either in isolation or as part of anterior hypopituitarism (growth hormone, thyroid hormone, or gonadotropin deficiencies). Common but less frequent features are peripheral neuropathy (usually of axonal type manifesting as reduced distal reflexes, diminished vibratory sensation, and/or distal muscle wasting); hair anomalies (long eyelashes, bushy eyebrows, or scalp alopecia); short stature; and impaired cognitive functioning (learning disabilities in children; deficits in attention, visuospatial abilities, and recall in adults). Some of these features can occur in distinct clusters on the phenotypic continuum: Boucher-Neuhäuser syndrome (cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism); Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes); Oliver-McFarlane syndrome (trichomegaly, chorioretinal dystrophy, short stature, intellectual disability, and hypopituitarism); Laurence-Moon syndrome; and spastic paraplegia type 39 (SPG39) (upper motor neuron involvement, peripheral neuropathy, and sometimes reduced cognitive functioning and/or cerebellar ataxia).

A rare syndrome characterized by congenital ptosis and posterior fusion of the lumbosacral vertebrae. It has been described in a mother and her two daughters.

Lymphocytic vasculitis is one of several skin conditions which are collectively referred to as cutaneous vasculitis. In lymphocytic vasculitis, white blood cells (lymphocytes) cause damage to blood vessels in the skin. This condition is thought to be caused by a number of factors, but the exact cause of most cases is not known. This disease can present with a variety of symptoms, depending on the size, location, and severity of the affected area. In a minority of patients, cutaneous vasculitis can be part of a more severe vasculitis affecting other organs in the body - this is known as systemic vasculitis.

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.

Any hypothyroidism, congenital, nongoitrous in which the cause of the disease is a mutation in the NKX2-5 gene.

10q26 deletion syndrome is a condition that results from the loss (deletion) of a small piece of chromosome 10 in each cell. The deletion occurs on the long (q) arm of the chromosome at a position designated 10q26.\n\nThe signs and symptoms of 10q26 deletion syndrome vary widely, even among affected members of the same family. Among the more common features associated with this chromosomal change are distinctive facial features, mild to moderate intellectual disability, growth problems, and developmental delay. People with 10q26 deletion syndrome often have delayed development of speech and of motor skills such as sitting, crawling, and walking. Some have limited speech throughout life. Affected individuals may experience seizures, attention-deficit/hyperactivity disorder (ADHD), poor impulse control (impulsivity), or exhibit autistic behaviors that affect communication and social interaction.\n\nA range of facial features is seen in people with 10q26 deletion syndrome, but not all affected individuals have these features. Facial features of people with 10q26 deletion syndrome may include a prominent or beaked nose, a broad nasal bridge, a small jaw (micrognathia), malformed ears that are low set, a thin upper lip, and an unusually small head size (microcephaly). Many affected individuals have widely spaced eyes (hypertelorism) that do not look in the same direction (strabismus). Some people with this condition have a short neck with extra folds of skin (webbed neck).\n\nLess common signs and symptoms can occur in 10q26 deletion syndrome. Skeletal problems include a spine that curves to the side (scoliosis), limited movement in the elbows or other joints, or curved fifth fingers and toes (clinodactyly). Slow growth before and after birth can also occur in affected individuals. Males with this condition may have genital abnormalities, such as a small penis (micropenis), undescended testes (cryptorchidism), or the urethra opening on the underside of the penis (hypospadias). Some people with 10q26 deletion syndrome have kidney abnormalities, heart defects, breathing problems, recurrent infections, or hearing or vision problems.

Hereditary sensory and autonomic neuropathy type II (HSAN2) is characterized by progressively reduced sensation to pain, temperature, and touch. Onset can be at birth and is often before puberty. The sensory deficit is predominantly distal with the lower limbs more severely affected than the upper limbs. Over time sensory function becomes severely reduced. Unnoticed injuries and neuropathic skin promote ulcerations and infections that result in spontaneous amputation of digits or the need for surgical amputation. Osteomyelitis is common. Painless fractures can complicate the disease. Autonomic disturbances are variable and can include hyperhidrosis, tonic pupils, and urinary incontinence in those with more advanced disease.

Hypochromic microcytic anemia with iron overload is a condition that impairs the normal transport of iron in cells. Iron is an essential component of hemoglobin, which is the substance that red blood cells use to carry oxygen to cells and tissues throughout the body. In this condition, red blood cells cannot access iron in the blood, so there is a decrease of red blood cell production (anemia) that is apparent at birth. The red blood cells that are produced are abnormally small (microcytic) and pale (hypochromic). Hypochromic microcytic anemia with iron overload can lead to pale skin (pallor), tiredness (fatigue), and slow growth.\n\nIn hypochromic microcytic anemia with iron overload, the iron that is not used by red blood cells accumulates in the liver, which can impair its function over time. The liver problems typically become apparent in adolescence or early adulthood.

White sponge nevus is a rare autosomal dominant disorder of noncornifying squamous epithelial differentiation that presents clinically as white, soft, thick plaques of the oral mucosa. Less frequently, the mucous membranes of the nose, esophagus, genitalia, and rectum are involved. Histopathologic features, including epithelial thickening, parakeratosis, extensive vacuolization of the suprabasal keratinocytes, and compact aggregates of keratin intermediate filaments in the upper spinus layers resemble those found in epidermal disorders shown to be associated with keratin defects (summary by Richard et al., 1995). Genetic Heterogeneity of White Sponge Nevus White sponge nevus-2 (WSN2; 615785) is caused by mutation in the KRT13 gene (148065) on chromosome 17q21.

Methemoglobinemia and ambiguous genitalia (METAG) is due to isolated 17,20-lyase deficiency, defined by apparently normal 17-alpha-hydroxylase activity but severely reduced 17,20-lyase activity of the CYP17A1 enzyme (609300), which results in sex steroid deficiency but normal glucocorticoid and mineralocorticoid reserve. The clinical phenotype is characterized by male undermasculinization, with absent or disturbed pubertal development in both 46,XY and 46,XX individuals. Mild to severe methemoglobinemia has been reported in these patients (Idkowiak et al., 2012). Other autosomal recessive methemoglobinemias include types I and II (see 250800), caused by mutation in the CYB5R3 gene (613213). Isolated 17,20-lyase deficiency can also be caused by mutation in the CYP17A1 gene (609300), and mutation in the POR gene can manifest clinically as isolated 17,20-lyase deficiency (see 124015.0016).

VLDLR cerebellar hypoplasia (VLDLR-CH) is characterized by non-progressive congenital ataxia that is predominantly truncal and results in delayed ambulation, moderate-to-profound intellectual disability, dysarthria, strabismus, and seizures. Children either learn to walk very late (often after age 6 years) or never achieve independent ambulation. Brain MRI findings include hypoplasia of the inferior portion of the cerebellar vermis and hemispheres, simplified gyration of the cerebral hemispheres, and small brain stem – particularly the pons.

The phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS) is now known to be a continuum that includes the classic phenotype as well as paroxysmal exercise-induced dyskinesia and epilepsy (previously known as dystonia 18 [DYT18]) and paroxysmal choreoathetosis with spasticity (previously known as dystonia 9 [DYT9]), atypical childhood absence epilepsy, myoclonic astatic epilepsy, and paroxysmal non-epileptic findings including intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The classic phenotype is characterized by infantile-onset seizures, delayed neurologic development, acquired microcephaly, and complex movement disorders. Seizures in classic early-onset Glut1 DS begin before age six months. Several seizure types occur: generalized tonic or clonic, focal, myoclonic, atypical absence, atonic, and unclassified. In some infants, apneic episodes and abnormal episodic eye-head movements similar to opsoclonus may precede the onset of seizures. The frequency, severity, and type of seizures vary among affected individuals and are not related to disease severity. Cognitive impairment, ranging from learning disabilities to severe intellectual disability, is typical. The complex movement disorder, characterized by ataxia, dystonia, and chorea, may occur in any combination and may be continuous, paroxysmal, or continual with fluctuations in severity influenced by environmental factors such as fasting or with infectious stress. Symptoms often improve substantially when a ketogenic diet is started.

Epidermodysplasia verruciformis (EV) is a rare genodermatosis associated with a high risk of skin cancer. EV results from an abnormal susceptibility to specific related human papillomavirus (HPV) genotypes and to the oncogenic potential of some of them, mainly HPV5. Infection with EV-associated HPV leads to the early development of disseminated flat wart-like and pityriasis versicolor-like lesions. Patients are unable to reject their lesions, and cutaneous Bowen carcinomas in situ and invasive squamous cell carcinomas develop in about half of them, mainly on sun-exposed areas (summary by Ramoz et al., 2000). Genetic Heterogeneity of Susceptibility to Epidermodysplasia Verruciformis Susceptibility to EV2 (618231) is conferred by mutation in the TMC8 gene (605829) on chromosome 17q25; EV3 (618267) by mutation in the CIB1 gene (602293) on chromosome 15q26; EV4 (618307) by mutation in the RHOH gene (602037) on chromosome 4p13; and EV5 (618309) by mutation in the IL7 gene (146660) on chromosome 8q12.

Any secretory diarrhea in which the cause of the disease is a mutation in the SPINT2 gene.