Factor VIII (FVIII) is an essential blood-clotting protein, also known as anti-hemophilic factor (AHF). In humans, factor VIII is encoded by the F8 gene. Defects in this gene results in hemophilia A, a recessive X-linked coagulation disorder.
Factor VIII participates in blood coagulation; it is a cofactor for factor IXa which, in the presence of Ca+2 and phospholipids forms a complex that converts factor X to the activated form Xa. The factor VIII gene produces two alternatively spliced transcripts. Transcript variant 1 encodes a large glycoprotein, isoform a, which circulates in plasma and associates with von Willebrand factor in a noncovalent complex. This protein undergoes multiple cleavage events. Transcript variant 2 encodes a putative small protein, isoform b, which consists primarily of the phospholipid binding domain of factor VIIIc. This binding domain is essential for coagulant activity.
People with high levels of factor VIII are at increased risk for deep vein thrombosis and pulmonary embolism.
Read more about Factor VIII: Genetics, Physiology, Therapeutic Use, Contamination Scandal
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