Resistance to activated protein C and factor V Leiden as risk factors for venous thrombosis.

The recent discovery of the factor V Leiden mutation as the molecular defect in the large majority of APC-resistant individuals, has drastically changed our view on familial thrombophilia and it has contributed to a better understanding of the interaction of genetic and environmental risk factors. It has offered firm support for the view that venous thrombosis is a multifactorial disease and that the risk of thrombosis will increase as the number of genetic and/or environmental risk factors increases.