Hemophilia A: Classic hemophilia, which is due to a profound deficiency in the activity of clotting factor VIII. Affected individuals suffer hemorrhage into joints and muscles, easy bruising, and prolonged bleeding from wounds. The disease is inherited as an X-linked trait, so males are affected and females carry the gene. Treatment involves administration of blood products that introduce clotting factor VIII and replace lost blood. Use of contaminated blood products exposed many people with hemophilia to HIV infection in the 1980s and 1990s. Hemophilia A has affected the Russian royal house and the descendants of Queen Victoria.