Activated Protein C (APC) Resistance Ratio
Activated protein C (APC) normally has an anticoagulant effect. Some patients with recurrent venous thrombosis do not show the expected anticoagulant effect when activated protein C (APC) is added to clotting tests, and these persons were termed "resistant" to the anticoagulant effect of APC. Many of these patients have an hereditary disorder (autosomal dominant inheritance) related to a mutation in factor V (Factor V Leiden) which resists proteolysis by APC when activated to factor Va.
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