Factor v resistance to activated protein c (apc)

[Oralee]

Mutations of factor V make it resistant to its normal cleavage and inactivation by activated protein C, and they predispose to venous thrombosis.
(See also Overview of Thrombotic Disorders.)
Activated protein C (APC), in complex with protein S, degrades coagulation factors Va and VIIIa, thus inhibiting coagulation (see figure Pathways in blood coagulation). Any of several mutations to factor V make it resistant to inactivation by APC, increasing the tendency for thrombosis.
Factor V Leiden is the most common of these mutations. Homozygous mutations increase the risk of thrombosis more than do heterozygous mutations.
Factor V Leiden as a single gene defect is present in about 5% of European populations, but it rarely occurs in native Asian or African populations. It is present in 20 to 60% of patients with quot;spontaneousquot; venous thrombosis.