HEMOPHILIA

Transmission of hemophilia (A) Mating of affected hemophilic man and normal woman-all 1/4 also spelled haemophilia hereditary bleeding disorder caused by a deficiency of a substance necessary for blood clotting. In the classical form of hemophilia, the missing substance is factor VIII, or antihemophilic globulin (AHG). The transmission of this condition is characteristically sex-linked, being expressed mostly only in males but transmitted solely by females; sons of a hemophilic male are normal, but daughters, although outwardly normal, may transmit the trait as an overt defect to half their sons and as a recessive or hidden trait to half their daughters (see chart). The incidence of hemophilia tends to be familial; its existence in certain royal families of Europe is well known. The increased tendency to bleeding usually becomes noticeable early in life and may lead to severe anemia or even death. Large bruises of the skin and soft tissue are often seen, usually following injury so trivial as to be unnoticed. There may also be bleeding in the mouth, nose, and gastrointestinal tract. After childhood, hemorrhages in the joints-notably the knees, ankles, and elbows-are frequent, resulting in swelling and impaired function. Persons with hemophilia are ordinarily advised to avoid activities that might expose them to bodily injury. The management of bleeding episodes includes the local application of hemostatic agents, such as thrombin, and the transfusion of fresh blood (antihemophilic activity rapidly decreases in stored blood) when hemorrhage is excessive. Various commercial preparations containing antihemophilic concentrates from normal blood are also available. Hemophilia may also be attributed to a deficiency of plasma thromboplastin component (PTC), or factor IX, and of plasma thromboplastin antecedent (PTA); PTC deficiency (also called Christmas disease and hemophilia B) is clinically indistinguishable from classical hemophilia, whereas PTA deficiency may be transmitted by both males and females and is found in both sexes.