APC resistance

a.k.a. Activated-protein C resistance can be either acquired or inherited. The most common cause of APC resistance is due to a mutation at the cleavage site in Factor V, in which the amino acid Arg506 is replaced with Gln, producing Factor V Leiden. This mutation prevents APC from inactivating Factor V. APC resistance is usually associated with Factor V Leiden and results in an increased risk of thrombosis.