Factor viii

Factor VIII (also known as Antihemophilic Factor or AHF) is an essential blood-clotting protein, also known as a coagulation factor. A deficiency of Factor VIII is the cause of the most common type of hemophilia, known as Hemophilia A.

Function

Factor VIII is produced in the liver and circulates in the bloodstream in an inactive form, bound to another molecule called von Willebrand factor, until an injury that involves bleeding occurs. In response to injury, coagulation factor VIII is activated and separates from von Willebrand factor. The active protein (sometimes written as coagulation factor VIIIa) interacts with another coagulation factor called factor IX. This interaction sets off a chain of additional chemical reactions that form a blood clot.

Role in Disease

Factor VIII is deficient or defective in individuals with Hemophilia A and can lead to excessive, often spontaneous bleeding. Treatment for Hemophilia A involves replacing the missing Factor VIII. In some cases, the immune system of a person receiving Factor VIII replacement therapy sees the treatment as foreign and develops proteins called antibodies that inactivate the Factor VIII. This response is known as an inhibitor and is the most serious complication of replacement therapy.

See Also

• Hemophilia
• Coagulation
• von Willebrand factor
• Antibodies

References

Factor viii Resources
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