Glanzmann thrombasthenia is a bleeding disorder that is characterized by prolonged or spontaneous bleeding starting from birth. People with Glanzmann thrombasthenia tend to bruise easily, have frequent nosebleeds (epistaxis), and may bleed from the gums. They may also develop red or purple spots on the skin caused by bleeding underneath the skin (petechiae) or swelling caused by bleeding within tissues (hematoma). Glanzmann thrombasthenia can also cause prolonged bleeding following injury, trauma, or surgery (including dental work). Women with this condition can have prolonged and sometimes abnormally heavy menstrual bleeding. Affected women also have an increased risk of excessive blood loss during pregnancy and childbirth.\n\nAbout a quarter of individuals with Glanzmann thrombasthenia have bleeding in the gastrointestinal tract, which often occurs later in life. Rarely, affected individuals have bleeding inside the skull (intracranial hemorrhage) or joints (hemarthrosis).\n\nThe severity and frequency of the bleeding episodes in Glanzmann thrombasthenia can vary greatly among affected individuals, even in the same family. Spontaneous bleeding tends to become less frequent with age.

Von Willebrand disease (VWD), a congenital bleeding disorder caused by deficient or defective plasma von Willebrand factor (VWF), may only become apparent on hemostatic challenge, and bleeding history may become more apparent with increasing age. Recent guidelines on VWD have recommended taking a VWF level of 30 or 40 IU/dL as a cutoff for those diagnosed with the disorder. Individuals with VWF levels greater than 30 IU/dL and lower than 50 IU/dL can be described as having a risk factor for bleeding. This change in guidelines significantly alters the proportion of individuals with each disease type. Type 1 VWD (~30% of VWD) typically manifests as mild mucocutaneous bleeding. Type 2 VWD accounts for approximately 60% of VWD. Type 2 subtypes include: Type 2A, which usually manifests as mild-to-moderate mucocutaneous bleeding; Type 2B, which typically manifests as mild-to-moderate mucocutaneous bleeding that can include thrombocytopenia that worsens in certain circumstances; Type 2M, which typically manifests as mild-moderate mucocutaneous bleeding; Type 2N, which can manifest as excessive bleeding with surgery and mimics mild hemophilia A. Type 3 VWD (<10% of VWD) manifests with severe mucocutaneous and musculoskeletal bleeding.

Von Willebrand disease (VWD), a congenital bleeding disorder caused by deficient or defective plasma von Willebrand factor (VWF), may only become apparent on hemostatic challenge, and bleeding history may become more apparent with increasing age. Recent guidelines on VWD have recommended taking a VWF level of 30 or 40 IU/dL as a cutoff for those diagnosed with the disorder. Individuals with VWF levels greater than 30 IU/dL and lower than 50 IU/dL can be described as having a risk factor for bleeding. This change in guidelines significantly alters the proportion of individuals with each disease type. Type 1 VWD (~30% of VWD) typically manifests as mild mucocutaneous bleeding. Type 2 VWD accounts for approximately 60% of VWD. Type 2 subtypes include: Type 2A, which usually manifests as mild-to-moderate mucocutaneous bleeding; Type 2B, which typically manifests as mild-to-moderate mucocutaneous bleeding that can include thrombocytopenia that worsens in certain circumstances; Type 2M, which typically manifests as mild-moderate mucocutaneous bleeding; Type 2N, which can manifest as excessive bleeding with surgery and mimics mild hemophilia A. Type 3 VWD (<10% of VWD) manifests with severe mucocutaneous and musculoskeletal bleeding.

RUNX1 familial platelet disorder with associated myeloid malignancies (RUNX1-FPDMM) is characterized by prolonged bleeding and/or easy bruising and an increased risk of developing a hematologic malignancy. RUNX1-FPDMM is characterized by thrombocytopenia with normal platelet size; bleeding is often greater than expected due to qualitative platelet dysfunction. Myeloid malignancies are the most common, including acute myelogenous leukemia (and myelodysplastic syndrome. T- and B-cell acute lymphoblastic leukemias and lymphomas have also been reported, as well as skin manifestations (e.g., eczema, psoriasis).

DFNA1 is an autosomal dominant form of progressive hearing loss with onset in the first decade. Some patients have mild thrombocytopenia and enlarged platelets, although most of these individuals do not have significant bleeding tendencies (summary by Neuhaus et al., 2017).

Bartter syndrome refers to a group of disorders that are unified by autosomal recessive transmission of impaired salt reabsorption in the thick ascending loop of Henle with pronounced salt wasting, hypokalemic metabolic alkalosis, and hypercalciuria. Clinical disease results from defective renal reabsorption of sodium chloride in the thick ascending limb (TAL) of the Henle loop, where 30% of filtered salt is normally reabsorbed (Simon et al., 1997). Patients with antenatal forms of Bartter syndrome typically present with premature birth associated with polyhydramnios and low birth weight and may develop life-threatening dehydration in the neonatal period. Patients with classic Bartter syndrome (see BARTS3, 607364) present later in life and may be sporadically asymptomatic or mildly symptomatic (summary by Simon et al., 1996 and Fremont and Chan, 2012). For a discussion of genetic heterogeneity of Bartter syndrome, see 607364.

Sitosterolemia is characterized by: Hypercholesterolemia (especially in children) which (1) shows an unexpected significant lowering of plasma cholesterol level in response to low-fat diet modification or to bile acid sequestrant therapy; or (2) does not respond to statin therapy; Tendon xanthomas or tuberous (i.e., planar) xanthomas that can occur in childhood and in unusual locations (heels, knees, elbows, and buttocks); Premature atherosclerosis, which can lead to angina, aortic valve involvement, myocardial infarction, and sudden death; Hemolytic anemia, abnormally shaped erythrocytes (stomatocytes), and large platelets (macrothrombocytopenia). On occasion, the abnormal hematologic findings may be the initial presentation or the only clinical feature of this disorder. Arthritis, arthralgias, and splenomegaly may sometimes be seen and one study has concluded that "idiopathic" liver disease could be undiagnosed sitosterolemia. The clinical spectrum of sitosterolemia is probably not fully appreciated due to underdiagnosis and the fact that the phenotype in infants is likely to be highly dependent on diet.

Platelet prostaglandin-endoperoxidase synthase-1 deficiency is a hematologic disorder characterized by mildly increased bleeding due to a platelet defect. The PTGS1 gene (176805) encodes prostaglandin-endoperoxidase synthase-1, also known as COX1 or PGHS1, which catalyzes the formation of prostaglandin G2 (PGG2) and prostaglandin H2 from arachidonic acid, and the downstream formation of thromboxane A2 (TXA2) and prostacyclin. Thromboxane A2 is important for platelet aggregation (summary by Matijevic-Aleksic et al., 1996).

Hermansky-Pudlak syndrome (HPS) is characterized by oculocutaneous albinism, a bleeding diathesis, and, in some individuals, pulmonary fibrosis, granulomatous colitis, or immunodeficiency. Ocular findings include reduced iris pigment with iris transillumination, reduced retinal pigment, foveal hypoplasia with significant reduction in visual acuity (usually in the range of 20/50 to 20/400), nystagmus, and increased crossing of the optic nerve fibers. Hair color ranges from white to brown; skin color ranges from white to olive and is usually a shade lighter than that of other family members. The bleeding diathesis can result in variable bruising, epistaxis, gingival bleeding, postpartum hemorrhage, colonic bleeding, and prolonged bleeding with menses or after tooth extraction, circumcision, and other surgeries. Pulmonary fibrosis, a restrictive lung disease, typically causes symptoms in the early thirties and can progress to death within a decade. Granulomatous colitis is severe in about 15% of affected individuals. Neutropenia and/or immune defects occur primarily in individuals with pathogenic variants in AP3B1 and AP3D1.

XLANP is an X-linked recessive hematologic disorder characterized by early-onset anemia and bone marrow erythroid hypoplasia with variable neutropenia. Some patients may have low platelets or platelet abnormalities. The severity is variable. Some patients have shown a favorable response to corticosteroid treatment (summary by Hollanda et al., 2006 and Sankaran et al., 2012). In some cases, the disorder may resemble Diamond-Blackfan anemia (see, e.g., DBA1; 105650) (Sankaran et al., 2012; Parrella et al., 2014; Klar et al., 2014).

Hermansky-Pudlak syndrome (HPS) is characterized by oculocutaneous albinism, a bleeding diathesis, and, in some individuals, pulmonary fibrosis, granulomatous colitis, or immunodeficiency. Ocular findings include reduced iris pigment with iris transillumination, reduced retinal pigment, foveal hypoplasia with significant reduction in visual acuity (usually in the range of 20/50 to 20/400), nystagmus, and increased crossing of the optic nerve fibers. Hair color ranges from white to brown; skin color ranges from white to olive and is usually a shade lighter than that of other family members. The bleeding diathesis can result in variable bruising, epistaxis, gingival bleeding, postpartum hemorrhage, colonic bleeding, and prolonged bleeding with menses or after tooth extraction, circumcision, and other surgeries. Pulmonary fibrosis, a restrictive lung disease, typically causes symptoms in the early thirties and can progress to death within a decade. Granulomatous colitis is severe in about 15% of affected individuals. Neutropenia and/or immune defects occur primarily in individuals with pathogenic variants in AP3B1 and AP3D1.

Hermansky-Pudlak syndrome (HPS) is characterized by oculocutaneous albinism, a bleeding diathesis, and, in some individuals, pulmonary fibrosis, granulomatous colitis, or immunodeficiency. Ocular findings include reduced iris pigment with iris transillumination, reduced retinal pigment, foveal hypoplasia with significant reduction in visual acuity (usually in the range of 20/50 to 20/400), nystagmus, and increased crossing of the optic nerve fibers. Hair color ranges from white to brown; skin color ranges from white to olive and is usually a shade lighter than that of other family members. The bleeding diathesis can result in variable bruising, epistaxis, gingival bleeding, postpartum hemorrhage, colonic bleeding, and prolonged bleeding with menses or after tooth extraction, circumcision, and other surgeries. Pulmonary fibrosis, a restrictive lung disease, typically causes symptoms in the early thirties and can progress to death within a decade. Granulomatous colitis is severe in about 15% of affected individuals. Neutropenia and/or immune defects occur primarily in individuals with pathogenic variants in AP3B1 and AP3D1.

BDPLT21 is a hematologic disorder characterized by increased risk of bleeding resulting from a functional platelet defect. Platelets have decreased or even absent dense bodies and abnormally enlarged and fused alpha-granules, and they show defective secretion and aggregation responses to agonists. Platelets are usually enlarged, and some patients may have mild to moderate thrombocytopenia (summary by Saultier et al., 2017).

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.

Recurrent gastrointestinal ulceration with dysfunctional platelets (GURDP) is an autosomal recessive disorder characterized by onset of severe gastrointestinal mucosal ulceration in early childhood. Affected individuals may have secondary iron deficiency anemia or malnourishment. Studies of platelet aggregation show a functional defect associated with decreased thromboxane-A2 production and decreased eicosanoid biosynthesis. The gastrointestinal disease is believed to result from decreased or absent production of prostaglandins that protect the gut mucosa (summary by Adler et al., 2008 and Faioni et al., 2014).

Autosomal dominant isolated macrothrombocytopenia-1 (MACTHC1) is characterized by the finding of low platelet numbers and abnormally large platelets with irregular shapes. Affected individuals do not have increased bleeding episodes and platelet function is normal; macrothrombocytopenia is usually an incidental laboratory finding (Kunishima et al., 2009). Genetic Heterogeneity of Isolated Macrothrombocytopenia See also MACTHC2 (619840), caused by mutation in the TUBA8 gene (605742) on chromosome 22q11.