Hemophilia

Hemophilia, hereditary disease in which the blood clots very slowly, such that a minor cut or bruise can cause prolonged bleeding, and there is a tendency to bleed internally without any obvious cause. It affects only males, but is transmitted in the genes of females. The genetic defect is the inability to synthesize a protein—factor VIII—needed for normal clotting of the blood. The severity of the disease depends on how much factor VIII is produced by the body; in severe cases, where no factor VIII is made, internal bleeding can lead to massive hemorrhages and can erode the joints of the arms and legs. The disease can now be controlled by giving the hemophiliac transfusions or intravenous injections of factor VIII that has been collected from donated blood. A small percentage of hemophiliacs lack clotting factor IX; this type of hemophilia is known as Christmas disease.

See also: Blood.