Hemophilia is a relatively rare hereditary genetic disorder characterized by an inability to produce a clot capable of stopping bleeding. Mainly men are affected by hemophilia A (factor VIII-deficient) and hemophilia B (factor IX-deficient), as is the case with most recessive, X-chromosomal disorders. In congenital hemophilia, the impaired production or functioning of one of the factors involved in the coagulation cascade is responsible for compromised blood coagulation, leading to uncontrolled and prolonged bleeding. The current standard of treatment for these patients is the replacement of the missing factor via clotting factor concentrate products. However, some patients develop antibodies against these therapies, called inhibitors, making treatment much more difficult.
Patients without hemophilia who develop inhibitors against clotting factor VIII or factor IX are diagnosed as having acquired hemophilia A or B, respectively. Although acquired hemophilia patients and congenital hemophilia patients with inhibitors share some similar traits and treatment options, acquired hemophilia affects men and women similarly, and has a distinct bleeding pattern.
Another disease associated with blood coagulation dysfunction is von Willebrand disease, which is caused by a deficiency in von Willebrand factor. Although von Willebrand disease is more common than hemophilia, it is relatively less severe, with most patients exhibiting mild disease that does not require regular treatment unless bleeding episodes caused by trauma or invasive procedures are uncontrollable.