Hemophilia B is characterized by deficiency in factor IX clotting activity that results in prolonged oozing after injuries, tooth extractions, or surgery, and delayed or recurrent bleeding prior to complete wound healing. The age of diagnosis and frequency of bleeding episodes are related to the level of factor IX clotting activity. In any individual with hemophilia B, bleeding episodes may be more frequent in childhood and adolescence than in adulthood. Individuals with severe hemophilia B are usually diagnosed during the first two years of life. Without prophylactic treatment, they may average up to two to five spontaneous bleeding episodes each month, including spontaneous joint or muscle bleeds, and prolonged bleeding or excessive pain and swelling from minor injuries, surgery, and tooth extractions. Individuals with moderate hemophilia B seldom have spontaneous bleeding, although it varies between individuals; however, they do have prolonged or delayed oozing after relatively minor trauma and are usually diagnosed before age five to six years. The frequency of bleeding episodes varies from once a month to once a year. Individuals with mild hemophilia B do not have spontaneous bleeding episodes; however, without pre- and postoperative treatment, abnormal bleeding occurs with surgery or tooth extractions. The frequency of bleeding may vary from once a year to once every ten years. Individuals with mild hemophilia B are often not diagnosed until later in life. Approximately 30% of heterozygous females have factor IX clotting activity lower than 40% and are at risk for bleeding (even if the affected family member has mild hemophilia B). As in males, bleeding severity generally correlates with factor levels. After major trauma or invasive procedures, prolonged or excessive bleeding usually occurs, regardless of severity.

Hemophilia A is characterized by deficiency in factor VIII clotting activity that results in prolonged bleeding after injuries, tooth extractions, or surgery, and delayed or recurrent bleeding prior to complete wound healing. The age of diagnosis and frequency of bleeding episodes are related to the level of factor VIII clotting activity. Individuals with severe hemophilia A are usually diagnosed during the first two years of life following oral or soft tissue bleeding either with procedures or due to a known family history of hemophilia. Without prophylactic treatment, individuals may average up to two to five spontaneous bleeding episodes each month including spontaneous joint bleeds or deep-muscle hematomas, and prolonged bleeding or excessive pain and swelling from minor injuries, surgery, and tooth extractions. Individuals with moderate hemophilia A seldom have spontaneous bleeding, although it varies between individuals; however, they do have prolonged or delayed bleeding after relatively minor trauma and are usually diagnosed before age five to six years; the frequency of bleeding episodes varies, usually from once a month to once a year. Individuals with mild hemophilia A do not have spontaneous bleeding episodes; however, without pre- and postoperative treatment, abnormal bleeding occurs with surgery or tooth extractions; the frequency of bleeding episodes varies widely, typically from once a year to once every ten years. Individuals with mild hemophilia A are often not diagnosed until later in life. Approximately 30% of heterozygous females have factor VIII clotting activity below 40% and are at risk for bleeding (even if males in the family are only mildly affected). After major trauma or invasive procedures, prolonged or excessive bleeding usually occurs, regardless of severity. In addition, 25% of heterozygous females with normal factor VIII clotting activity report an increased bleeding tendency.

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).

A rare, genetic, congenital vitamin K-dependant coagulation factor deficiency disorder characterized by decreased levels or absence of coagulation factor VII (FVII), resulting in bleeding diathesis of variable severity.

A rare inherited bleeding disorder with a decreased antigen and/or activity of factor X (FX) and characterized by mild to severe bleeding symptoms.

Von Willebrand disease (VWD) is characterized by mucocutaneous bleeding and excessive bleeding with trauma and procedures. Individuals with more severe forms of VWD are also at-risk for musculoskeletal bleeding. Mucocutaneous bleeding can include easy bruising, prolonged bleeding from minor wounds, epistaxis, oral cavity bleeding, heavy menstrual bleeding, gastrointestinal bleeding, and bleeding with hemostatic challenges such as dental work, childbirth, and surgery. Bleeding severity can vary widely in VWD, even between affected individuals within the same family. For some with VWD the bleeding phenotype may only become apparent upon hemostatic challenge, while others may have frequent spontaneous bleeding.

Von Willebrand disease (VWD) is characterized by mucocutaneous bleeding and excessive bleeding with trauma and procedures. Individuals with more severe forms of VWD are also at-risk for musculoskeletal bleeding. Mucocutaneous bleeding can include easy bruising, prolonged bleeding from minor wounds, epistaxis, oral cavity bleeding, heavy menstrual bleeding, gastrointestinal bleeding, and bleeding with hemostatic challenges such as dental work, childbirth, and surgery. Bleeding severity can vary widely in VWD, even between affected individuals within the same family. For some with VWD the bleeding phenotype may only become apparent upon hemostatic challenge, while others may have frequent spontaneous bleeding.

The WAS-related disorders, which include Wiskott-Aldrich syndrome, X-linked thrombocytopenia (XLT), and X-linked neutropenia (XLN), are a spectrum of disorders of hematopoietic cells, with predominant defects of platelets and lymphocytes. Wiskott-Aldrich syndrome usually presents in infancy. Affected males have thrombocytopenia with intermittent mucosal bleeding, bloody diarrhea, and intermittent or chronic petechiae and purpura; recurrent bacterial, viral, fungal, and/or opportunistic infections; and eczema. Approximately 25%-40% of those who survive the early complications develop one or more autoimmune conditions including hemolytic anemia, immune thrombocytopenic purpura, immune-mediated neutropenia, vasculitis, rheumatoid arthritis, 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 small platelet volume and thrombocytopenia. Severe disease-related events include severe bleeding episodes (14%), autoimmunity (12%), life-threatening infections (7%), and malignancy (5%). Males with XLN typically have congenital neutropenia associated with myelodysplasia, hyperactive neutrophils, increased myeloid cell apoptosis, and lymphoid cell abnormalities.

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.

Quebec platelet disorder is an autosomal dominant bleeding disorder due to a gain-of-function defect in fibrinolysis. Although affected individuals do not exhibit systemic fibrinolysis, they show delayed onset bleeding after challenge, such as surgery. The hallmark of the disorder is markedly increased PLAU levels within platelets, which causes intraplatelet plasmin generation and secondary degradation of alpha-granule proteins. The disorder shows a favorable therapeutic response to fibrinolytic inhibitors (summary by Diamandis et al., 2009).

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.

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).

Alpha-2-plasmin inhibitor deficiency is a rare autosomal recessive hemorrhagic diathesis. Most bleeds are severe, appear during childhood, and, in a few cases, umbilical bleeding is the first manifestation. Some homozygous patients present only moderate bleeding (Favier et al., 2001).