MedGen

The WAS-related disorders, which include Wiskott-Aldrich syndrome, X-linked thrombocytopenia (XLT), and X-linked congenital neutropenia (XLN), are a spectrum of disorders of hematopoietic cells, with predominant defects of platelets and lymphocytes caused by pathogenic variants in WAS. WAS-related disorders usually present in infancy. Affected males have thrombocytopenia with intermittent mucosal bleeding, bloody diarrhea, and intermittent or chronic petechiae and purpura; eczema; and recurrent bacterial and viral infections, particularly of the ear. At least 40% of those who survive the early complications develop one or more autoimmune conditions including hemolytic anemia, immune thrombocytopenic purpura, immune-mediated neutropenia, rheumatoid arthritis, vasculitis, and immune-mediated damage to the kidneys and liver. Individuals with a WAS-related disorder, particularly those who have been exposed to Epstein-Barr virus (EBV), are at increased risk of developing lymphomas, which often occur in unusual, extranodal locations including the brain, lung, or gastrointestinal tract. Males with XLT have thrombocytopenia with small platelets; other complications of Wiskott-Aldrich syndrome, including eczema and immune dysfunction, are usually mild or absent. Males with XLN have congenital neutropenia, myeloid dysplasia, and lymphoid cell abnormalities. [from GeneReviews]

Ethylmalonic encephalopathy (EE) is a severe, early-onset, progressive disorder characterized by developmental delay / mild-to-severe intellectual disability; generalized infantile hypotonia that evolves into hypertonia, spasticity, and (in some instances) dystonia; generalized tonic-clonic seizures; and generalized microvascular damage (diffuse and spontaneous relapsing petechial purpura, hemorrhagic suffusions of mucosal surfaces, and chronic hemorrhagic diarrhea). Infants sometimes have frequent vomiting and loss of social interaction. Speech is delayed and in some instances absent. Swallowing difficulties and failure to thrive are common. Children may be unable to walk without support and may be wheelchair bound. Neurologic deterioration accelerates following intercurrent infectious illness, and the majority of children die in the first decade. [from GeneReviews]

Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known. [from GeneReviews]

Fucosidosis is an autosomal recessive lysosomal storage disease caused by defective alpha-L-fucosidase with accumulation of fucose in the tissues. Clinical features include angiokeratoma, progressive psychomotor retardation, neurologic signs, coarse facial features, and dysostosis multiplex. Fucosidosis has been classified into 2 major types. Type 1 is characterized by rapid psychomotor regression and severe neurologic deterioration beginning at about 6 months of age, elevated sweat sodium chloride, and death within the first decade of life. Type 2 is characterized by milder psychomotor retardation and neurologic signs, the development of angiokeratoma corporis diffusum, normal sweat salinity, and longer survival (Kousseff et al., 1976). [from OMIM]

Gaucher disease (GD) encompasses a continuum of clinical findings from a perinatal lethal disorder to an asymptomatic type. The identification of three major clinical types (1, 2, and 3) and two other subtypes (perinatal-lethal and cardiovascular) is useful in determining prognosis and management. GD type 1 is characterized by the presence of clinical or radiographic evidence of bone disease (osteopenia, focal lytic or sclerotic lesions, and osteonecrosis), hepatosplenomegaly, anemia and thrombocytopenia, lung disease, and the absence of primary central nervous system disease. GD types 2 and 3 are characterized by the presence of primary neurologic disease; in the past, they were distinguished by age of onset and rate of disease progression, but these distinctions are not absolute. Disease with onset before age two years, limited psychomotor development, and a rapidly progressive course with death by age two to four years is classified as GD type 2. Individuals with GD type 3 may have onset before age two years, but often have a more slowly progressive course, with survival into the third or fourth decade. The perinatal-lethal form is associated with ichthyosiform or collodion skin abnormalities or with nonimmune hydrops fetalis. The cardiovascular form is characterized by calcification of the aortic and mitral valves, mild splenomegaly, corneal opacities, and supranuclear ophthalmoplegia. Cardiopulmonary complications have been described with all the clinical subtypes, although varying in frequency and severity. [from GeneReviews]

The WAS-related disorders, which include Wiskott-Aldrich syndrome, X-linked thrombocytopenia (XLT), and X-linked congenital neutropenia (XLN), are a spectrum of disorders of hematopoietic cells, with predominant defects of platelets and lymphocytes caused by pathogenic variants in WAS. WAS-related disorders usually present in infancy. Affected males have thrombocytopenia with intermittent mucosal bleeding, bloody diarrhea, and intermittent or chronic petechiae and purpura; eczema; and recurrent bacterial and viral infections, particularly of the ear. At least 40% of those who survive the early complications develop one or more autoimmune conditions including hemolytic anemia, immune thrombocytopenic purpura, immune-mediated neutropenia, rheumatoid arthritis, vasculitis, and immune-mediated damage to the kidneys and liver. Individuals with a WAS-related disorder, particularly those who have been exposed to Epstein-Barr virus (EBV), are at increased risk of developing lymphomas, which often occur in unusual, extranodal locations including the brain, lung, or gastrointestinal tract. Males with XLT have thrombocytopenia with small platelets; other complications of Wiskott-Aldrich syndrome, including eczema and immune dysfunction, are usually mild or absent. Males with XLN have congenital neutropenia, myeloid dysplasia, and lymphoid cell abnormalities. [from GeneReviews]

The spectrum of CLCN7-related osteopetrosis includes infantile malignant CLCN7-related autosomal recessive osteopetrosis (ARO), intermediate autosomal osteopetrosis (IAO), and autosomal dominant osteopetrosis type II (ADOII; Albers-Schönberg disease). ARO. Onset is at birth. Findings may include: fractures; reduced growth; sclerosis of the skull base (with or without choanal stenosis or hydrocephalus) resulting in optic nerve compression, facial palsy, and hearing loss; absence of the bone marrow cavity resulting in severe anemia and thrombocytopenia; dental abnormalities, odontomas, and risk for mandibular osteomyelitis; and hypocalcemia with tetanic seizures and secondary hyperparathyroidism. Without treatment maximal life span in ARO is ten years. IAO. Onset is in childhood. Findings may include: fractures after minor trauma, characteristic skeletal radiographic changes found incidentally, mild anemia, and occasional visual impairment secondary to optic nerve compression. Life expectancy in IAO is usually normal. ADOII. Onset is usually late childhood or adolescence. Findings may include: fractures (in any long bone and/or the posterior arch of a vertebra), scoliosis, hip osteoarthritis, and osteomyelitis of the mandible or septic osteitis or osteoarthritis elsewhere. Cranial nerve compression is rare. [from GeneReviews]

Prolidase deficiency is characterized by skin lesions (typically severe, chronic, recalcitrant, and painful skin ulcers of the lower extremities and telangiectasias of the face and hands), recurrent infections (particularly of the skin and respiratory tract), dysmorphic facial features, variable intellectual disability, and organomegaly (typically splenomegaly but occasionally associated with hepatomegaly) with elevated liver enzymes. Skeletal anomalies, chronic pulmonary disease, anemia, thrombocytopenia, hypergammaglobulinemia, and hypocomplementemia are observed in a minority of affected individuals. An association between prolidase deficiency and autoimmune conditions – particularly systemic lupus erythematosus (SLE) – has been described. [from GeneReviews]

GATA1-related cytopenia is characterized by thrombocytopenia and/or anemia ranging from mild to severe. One or more of the following may also be present: platelet dysfunction, mild ß-thalassemia, neutropenia, and congenital erythropoietic porphyria (CEP) in males. Thrombocytopenia typically presents in infancy as a bleeding disorder with easy bruising and mucosal bleeding (e.g., epistaxis). Anemia ranges from minimal (mild dyserythropoiesis) to severe (hydrops fetalis requiring in utero transfusion). At the extreme end of the clinical spectrum, severe hemorrhage and/or erythrocyte transfusion dependence are life long; at the milder end, anemia and the risk for bleeding may decrease spontaneously with age. Heterozygous females may have mild-to-moderate symptoms such as menorrhagia. [from GeneReviews]

GATA1-related cytopenia is characterized by thrombocytopenia and/or anemia ranging from mild to severe. One or more of the following may also be present: platelet dysfunction, mild ß-thalassemia, neutropenia, and congenital erythropoietic porphyria (CEP) in males. Thrombocytopenia typically presents in infancy as a bleeding disorder with easy bruising and mucosal bleeding (e.g., epistaxis). Anemia ranges from minimal (mild dyserythropoiesis) to severe (hydrops fetalis requiring in utero transfusion). At the extreme end of the clinical spectrum, severe hemorrhage and/or erythrocyte transfusion dependence are life long; at the milder end, anemia and the risk for bleeding may decrease spontaneously with age. Heterozygous females may have mild-to-moderate symptoms such as menorrhagia. [from GeneReviews]

Leukocyte adhesion deficiency-3 (LAD3), also known as LAD1 variant (LAD1V), is an autosomal recessive disorder characterized by LAD1 (116920)-like immune deficiency and Glanzmann thrombasthenia (GT; 273800)-like bleeding problems. LAD3 results from mutations in FERMT3, or KINDLIN3, which encodes an intracellular protein that interacts with beta-integrins in hematopoietic cells. In LAD3, the adhesive functions of integrins on both leukocytes and platelets are disrupted, most likely due to defects in activation-dependent alterations of surface integrins that enable high-avidity binding to ligands on target cells, a process termed 'inside-out signaling' (Svensson et al., 2009; Zimmerman, 2009). For a discussion of genetic heterogeneity of leukocyte adhesion deficiency, see 116920. [from OMIM]

Individuals with ETV6 thrombocytopenia and predisposition to leukemia most often present with a lifelong history of thrombocytopenia, which is usually in the mild to moderate range. No syndromic features or associations are consistently shared across pedigrees. Affected individuals also have a moderate risk of developing a hematologic malignancy (with B-cell acute lymphoblastic leukemia [B-ALL] being the most common) and possibly other malignant solid tumors, particularly colorectal cancer. [from GeneReviews]

Autoimmune lymphoproliferative syndrome (ALPS), caused by defective lymphocyte homeostasis, is characterized by the following: Non-malignant lymphoproliferation (lymphadenopathy, hepatosplenomegaly with or without hypersplenism) that often improves with age. Autoimmune disease, mostly directed toward blood cells. Lifelong increased risk for both Hodgkin and non-Hodgkin lymphoma. In ALPS-FAS (the most common and best-characterized type of ALPS, associated with heterozygous germline pathogenic variants in FAS), non-malignant lymphoproliferation typically manifests in the first years of life, inexplicably waxes and wanes, and then often decreases without treatment in the second decade of life; in many affected individuals, however, neither splenomegaly nor the overall expansion of lymphocyte subsets in peripheral blood decreases. Although autoimmunity is often not present at the time of diagnosis or at the time of the most extensive lymphoproliferation, autoantibodies can be detected before autoimmune disease manifests clinically. In ALPS-FAS caused by homozygous or compound heterozygous (biallelic) pathogenic variants in FAS, severe lymphoproliferation occurs before, at, or shortly after birth, and usually results in death at an early age. ALPS-sFAS, resulting from somatic FAS pathogenic variants in selected cell populations, notably the alpha/beta double-negative T cells (a/ß-DNT cells), appears to be similar to ALPS-FAS resulting from heterozygous germline pathogenic variants in FAS, although lower incidence of splenectomy and lower lymphocyte counts have been reported in ALPS-sFAS and no cases of lymphoma have yet been published. [from GeneReviews]

Platelet-type bleeding disorder-16 (BDPLT16) is an autosomal dominant form of congenital macrothrombocytopenia associated with platelet anisocytosis. It is a disorder of platelet production. Affected individuals may have no or only mildly increased bleeding tendency. In vitro studies show mild platelet functional abnormalities (summary by Kunishima et al., 2011 and Nurden et al., 2011). Genetic Heterogeneity of Glanzmann Thrombasthenia-like with Macrothromocytopenia See BDPLT24 (619271), caused by mutation in the ITGB3 gene (173470) on chromosome 17q21.32. Together the ITGB2B and ITBG3 genes form an integrin, known as platelet glycoprotein GPIIb/III, that is expressed on platelets. [from OMIM]

A Bernard-Soulier syndrome characterized by autosomal dominant inheritance of mild to moderate bleeding tendency, thrombocytopenia, and an increased mean platelet size that has material basis in heterozygous mutations in the GP1BA gene on chromosome 17p. [from MONDO]

Platelet-type bleeding disorder-17 is an autosomal dominant disorder characterized by increased bleeding tendency due to abnormal platelet function. It is a type of 'gray platelet syndrome' because the platelets appear abnormal on light microscopy. Electron microscopy shows decreased or absent alpha-granules within platelets, and bone marrow biopsy shows increased numbers of abnormal megakaryocytes, suggesting a defect in megakaryopoiesis and platelet production. The bleeding severity is variable (summary by Monteferrario et al., 2014). [from OMIM]

MIRAGE syndrome is an acronym for the major findings of myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy. Cytopenias are typically seen soon after birth; thrombocytopenia is the most common followed by anemia and pancytopenia. Recurrent infections from early infancy include pneumonia, urinary tract infection, gastroenteritis, meningitis, otitis media, dermatitis, subcutaneous abscess, and sepsis. Reported genital phenotypes in those with 46,XY karyotype included hypospadias, microphallus, bifid shawl scrotum, ambiguous genitalia, or complete female genitalia. Hypoplastic or dysgenetic ovaries have been reported in females. Gastrointestinal complications include chronic diarrhea and esophageal dysfunction. Moderate-to-severe developmental delay is reported in most affected individuals. Autonomic dysfunction and renal dysfunction are also reported. [from GeneReviews]

Radioulnar synostosis with amegakaryocytic thrombocytopenia (RUSAT) is characterized by thrombocytopenia that progresses to pancytopenia, in association with congenital proximal fusion of the radius and ulna that results in extremely limited pronation and supination of the forearm (summary by Niihori et al., 2015). Genetic Heterogeneity of Radioulnar Synostosis with Amegakaryocytic Thrombocytopenia Radioulnar synostosis with amegakaryocytic thrombocytopenia-2 (RUSAT2; 616738) is caused by heterozygous mutation in the MECOM gene (165215) on chromosome 3q26. [from OMIM]

Alpha-N-acetylgalactosaminidase (NAGA) deficiency is a very rare lysosomal storage disorder with atypical features. It is clinically heterogeneous with 3 main phenotypes: type I is an infantile-onset neuroaxonal dystrophy (609241); type II, also known as Kanzaki disease, is an adult-onset disorder characterized by angiokeratoma corporis diffusum and mild intellectual impairment; and type III is an intermediate disorder (see 609241) with mild to moderate neurologic manifestations (Desnick and Schindler, 2001). [from OMIM]