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.

AIP familial isolated pituitary adenoma (AIP-FIPA) is defined as the presence of an AIP germline pathogenic variant in an individual with a pituitary adenoma (regardless of family history). The most commonly occurring pituitary adenomas in this disorder are growth hormone-secreting adenomas (somatotropinoma), followed by prolactin-secreting adenomas (prolactinoma), growth hormone and prolactin co-secreting adenomas (somatomammotropinoma), and nonfunctioning pituitary adenomas (NFPA). Rarely TSH-secreting adenomas (thyrotropinomas) are observed. Clinical findings result from excess hormone secretion, lack of hormone secretion, and/or mass effects (e.g., headaches, visual field loss). Within the same family, pituitary adenomas can be of the same or different type. Age of onset in AIP-FIPA is usually in the second or third decade.

Vascular Ehlers-Danlos syndrome (vEDS) is characterized by arterial, intestinal, and/or uterine fragility; thin, translucent skin; easy bruising; characteristic facial appearance (thin vermilion of the lips, micrognathia, narrow nose, prominent eyes); and an aged appearance to the extremities, particularly the hands. Vascular dissection or rupture, gastrointestinal perforation, or organ rupture are the presenting signs in most adults with vEDS. Arterial rupture may be preceded by aneurysm, arteriovenous fistulae, or dissection but also may occur spontaneously. The majority (60%) of individuals with vEDS who are diagnosed before age 18 years are identified because of a positive family history. Neonates may present with clubfoot, hip dislocation, limb deficiency, and/or amniotic bands. Approximately half of children tested for vEDS in the absence of a positive family history present with a major complication at an average age of 11 years. Four minor diagnostic features – distal joint hypermobility, easy bruising, thin skin, and clubfeet – are most often present in those children ascertained without a major complication.

Prothrombin deficiency is an extremely rare autosomal recessive bleeding disorder characterized by low levels of circulating prothrombin; it affects about 1 in 2,000,000 individuals. There are 2 main types: type I deficiency, known as true prothrombin deficiency or 'hypoprothrombinemia,' is defined as plasma levels of prothrombin being less than 10% of normal with a concomitant decrease in activity. These patients have severe bleeding from birth, including umbilical cord hemorrhage, hematomas, ecchymoses, hematuria, mucosal bleeding, hemarthroses, intracranial bleeding, gastrointestinal bleeding, and menorrhagia. Type II deficiency, known as 'dysprothrombinemia,' is characterized by normal or low-normal synthesis of a dysfunctional protein. Bleeding symptoms are more variable, depending on the amount of residual functional activity. Variant prothrombin gene alleles can result in 'hypoprothrombinemia' or 'dysprothrombinemia,' and individuals who are compound heterozygous for these 2 types of alleles have variable manifestations. Heterozygous mutation carriers, who have plasma levels between 40 and 60% of normal, are usually asymptomatic, but can show bleeding after tooth extraction or surgical procedures (review by Lancellotti and De Cristofaro, 2009).

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).

Deficiency of all vitamin K-dependent clotting factors leads to a bleeding tendency that is usually reversed by oral administration of vitamin K. Acquired forms of the disorder can be caused by intestinal malabsorption of vitamin K. Familial multiple coagulation factor deficiency is rare. Clinical symptoms of the disease include episodes of intracranial hemorrhage in the first weeks of life, sometimes leading to a fatal outcome. The pathomechanism is based on a reduced hepatic gamma-carboxylation of glutamic acid residues of all vitamin K-dependent blood coagulation factors, as well as the anticoagulant factors protein C (612283) and protein S (176880). Posttranslational gamma-carboxylation of proteins enables the calcium-dependent attachment of the proteins to the phospholipid bilayer of membranes, an essential prerequisite for blood coagulation. Vitamin K1 acts as a cofactor for the vitamin K-dependent carboxylase in liver microsomes, GGCX. Genetic Heterogeneity of Combined Deficiency of Vitamin K-Dependent Clotting Factors Combined deficiency of vitamin K-dependent clotting factors-2 (VKFCD2; 607473) is caused by mutation in the gene encoding vitamin K epoxide reductase (VKORC1; 608547) on chromosome 16p11.

Platelet-type bleeding disorder-8 (BDPLT8) is an autosomal recessive condition characterized by mild to moderate mucocutaneous bleeding and excessive bleeding after surgery or trauma. The defect is due to the inability of ADP to induce platelet aggregation (review by Cattaneo, 2011).

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).

Bleeding problems are common in the vascular type of Ehlers-Danlos syndrome and are caused by unpredictable tearing (rupture) of blood vessels and organs. These complications can lead to easy bruising, internal bleeding, a hole in the wall of the intestine (intestinal perforation), or stroke. During pregnancy, women with vascular Ehlers-Danlos syndrome may experience rupture of the uterus. Additional forms of Ehlers-Danlos syndrome that involve rupture of the blood vessels include the kyphoscoliotic, classical, and classical-like types.\n\nOther types of Ehlers-Danlos syndrome have additional signs and symptoms. The cardiac-valvular type causes severe problems with the valves that control the movement of blood through the heart. People with the kyphoscoliotic type experience severe curvature of the spine that worsens over time and can interfere with breathing by restricting lung expansion. A type of Ehlers-Danlos syndrome called brittle cornea syndrome is characterized by thinness of the clear covering of the eye (the cornea) and other eye abnormalities. The spondylodysplastic type features short stature and skeletal abnormalities such as abnormally curved (bowed) limbs. Abnormalities of muscles, including hypotonia and permanently bent joints (contractures), are among the characteristic signs of the musculocontractural and myopathic forms of Ehlers-Danlos syndrome. The periodontal type causes abnormalities of the teeth and gums.\n\nMany people with the Ehlers-Danlos syndromes have soft, velvety skin that is highly stretchy (elastic) and fragile. Affected individuals tend to bruise easily, and some types of the condition also cause abnormal scarring. People with the classical form of Ehlers-Danlos syndrome experience wounds that split open with little bleeding and leave scars that widen over time to create characteristic "cigarette paper" scars. The dermatosparaxis type of the disorder is characterized by loose skin that sags and wrinkles, and extra (redundant) folds of skin may be present.\n\nAn unusually large range of joint movement (hypermobility) occurs in most forms of Ehlers-Danlos syndrome, and it is a hallmark feature of the hypermobile type. Infants and children with hypermobility often have weak muscle tone (hypotonia), which can delay the development of motor skills such as sitting, standing, and walking. The loose joints are unstable and prone to dislocation and chronic pain. In the arthrochalasia type of Ehlers-Danlos syndrome, infants have hypermobility and dislocations of both hips at birth.\n\nThe various forms of Ehlers-Danlos syndrome have been classified in several different ways. Originally, 11 forms of Ehlers-Danlos syndrome were named using Roman numerals to indicate the types (type I, type II, and so on). In 1997, researchers proposed a simpler classification (the Villefranche nomenclature) that reduced the number of types to six and gave them descriptive names based on their major features. In 2017, the classification was updated to include rare forms of Ehlers-Danlos syndrome that were identified more recently. The 2017 classification describes 13 types of Ehlers-Danlos syndrome.\n\nEhlers-Danlos syndrome is a group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. Defects in connective tissues cause the signs and symptoms of these conditions, which range from mildly loose joints to life-threatening complications.

Factor XIII deficiency is an autosomal recessive hematologic disorder characterized by increased bleeding and poor wound healing. Most cases of congenital factor XIII deficiency result from mutation in the A subunit (Kangsadalampai et al., 1999). Ichinose et al. (1996, 2000) proposed a classification of factor XIII deficiency: XIIIA deficiency (formerly 'type II' F13 deficiency) and XIIIB deficiency (formerly 'type I' F13 deficiency), as well as a possible combined deficiency of the 2.

Factor XIII deficiency is an autosomal recessive hematologic disorder characterized by increased bleeding and poor wound healing. Most cases of congenital factor XIII deficiency result from mutation in the A subunit (Kangsadalampai et al., 1999). Ichinose et al. (1996, 2000) proposed a classification of factor XIII deficiency: XIIIA deficiency (formerly 'type II' F13 deficiency) and XIIIB deficiency (formerly 'type I' F13 deficiency), as well as a possible combined deficiency of the 2.

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.

Autosomal dominant Bernard-Soulier syndrome type A2 (BSSA2) is characterized by chronic macrothrombocytopenia with mild or no clinical symptoms, normal platelet function, and normal megakaryocyte count. When present, clinical findings include excessive ecchymoses, frequent epistaxis, gingival bleeding, prolonged menstrual periods, or prolonged bleeding after tooth extraction (Savoia et al., 2001). Genetic Heterogeneity of Bernard-Soulier Syndrome Homozygous or compound heterozygous mutations in the GP1BA gene cause classic autosomal recessive Bernard-Soulier syndrome (BSSA1; 231200).

Susceptibility to platelet-type bleeding disorder-13 is due to a defective thromboxane A2 receptor on platelets. The susceptibility is inherited in an autosomal dominant pattern, but clinical features, including mild mucocutaneous bleeding, occur only in the presence of a 'second hit' affecting platelet function; this second hit may be either in the TBXA2R gene or in another gene affecting the coagulation cascade (summary by Mumford et al., 2010).

Platelet-type bleeding disorder-11 is an autosomal recessive mild to moderate bleeding disorder caused by defective platelet activation and aggregation in response to collagen (summary by Dumont et al., 2009).

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.

Noncirrhotic portal hypertension-2 (NCPH2) is an autosomal recessive disorder characterized by signs of liver dysfunction that become apparent in the first decades of life. Affected individuals have jaundice, hyperbilirubinemia, pancytopenia, including neutropenia, lymphopenia, and thrombocytopenia, hepatosplenomegaly, and esophageal varices. Some patients may have recurrent infections or features suggestive of an immunodeficiency. Liver biopsy is notable for the absence of cirrhosis and the presence of nodular regeneration. Liver sinusoidal endothelial cells (LSECs) have abnormal expression of CD34 (142230) (summary by Drzewiecki et al., 2021). For a discussion of genetic heterogeneity of NCPH, see 617068.