**8.3 Factor V Leiden mutation and activated protein C resistance**

Factor V is a glycoprotein synthesized in the liver. With Factor V Leiden, a point mutation occurs when arginine is substituted by glutamine at position 506. This point mutation causes the activated Factor V to be resistant to inactivation by activated protein C thus causing a procoagulant state.

Clinically, patients may present with deep venous thrombosis in the lower extremities, or less commonly in the portal vein, cerebral vein, or superfi cial venous system.
