hemophilia (redirected from hemophilia B)

hemophilia (hē'məfĭl`ēə,–fēl`yə), genetic disease in which the clotting ability of the blood is impaired and excessive bleeding results. The disease is transmitted through females but almost invariably affects male offspring only. A male born to a carrier mother has a 50% chance of having the disease. A hemophiliac cannot pass the disease to his sons, but all his daughters will be carriers. There are two diseases usually classified as hemophilia: hemophilia A (classical hemophilia, or Factor VIII deficiency) and hemophilia B (Christmas disease, or Factor IX deficiency).

Small wounds and punctures are usually not a problem for hemophiliacs and can be treated as in a nonhemophiliac. Uncontrolled internal bleeding, however, can result in pain and swelling and permanent damage, especially to joints and muscles. The symptoms often first appear in toddlers as their joints begin to bear weight.

Treatment and Screening

There is no cure for hemophilia, but treatment has been refined in recent years. In the 1960s, infusion of concentrated clotting factors replaced the whole-blood or plasma transfusions previously necessary, allowing most to administer preventive treatment at home. In the 1980s, however, many hemophiliacs became infected with hepatitis or HIV (the AIDS virus) that was present in contaminated concentrated clotting factor. Blood donors are now screened, and commercial products are now heat-treated to kill the viruses. Genetic screening can identify carriers of hemophilia, and the status of fetuses can be now be ascertained early in pregnancy. Treatments under study include gene therapy by insertion of healthy factor VIII or IX genes and fetal tissue implants.

In History

Examples of the transmission of hemophilia have been found in several royal families. The family of Queen Victoria of England and, later, that of her granddaughter the Czarina Alexandra Feodorovna were affected. The apparent ability of Rasputin to check the hemophilia of the czarina's son was the basis of his hold over her and the czar. The family of Alfonso XIII of Spain, who married another granddaughter of Victoria, was also affected.

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hemophilia

Hereditary bleeding disorder caused by deficiency of a coagulation factor. Lack of factor VIII causes classic hemophilia; other types are caused by deficiency of factor IX or XI. The first two are transmitted by sex-linked heredity; the third has dominant inheritance and occurs in females as well as males. Spontaneous bleeding may occur. Even trivial injury can cause life-threatening blood loss. Drugs can be given to stop bleeding. Heavy blood loss requires blood transfusions.