Factor VIII

Factor eight, a key factor in the process of blood coagulation (clotting). Lack of normal factor VIII causes hemophilia (hemophilia A). The gene for classic hemophilia was long known to be on the X chromosome. Females carry the gene and transmit it to their hemophiliac sons. Female carriers are normal since they have another X chromosome that contains a normal gene to make factor VIII. Each of their sons has a one-half (50:50) risk of being a hemophiliac. Because the gene for hemophilia was clearly on the X chromosome, it was correctly inferred that the normal gene for Factor VIII was on the X. Factor VIII is also known as antihemophiliac factor or antihemophiliac globulin.

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factor VIII -'āt n a glycoprotein clotting factor of blood plasma that is essential for blood clotting and is absent or inactive in hemophilia called also antihemophilic factor, thromboplastinogen

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a coagulation factor normally present in blood. Deficiency of the factor, which is inherited by males from their mothers, results in haemophilia A. See also von Willebrand's disease.

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see under coagulation f's.