Use

This test provides information about additional risk for venous thrombosis among individuals known to be heterozygous for factor V Leiden (one copy of mutation). This knowledge aids in prevention of venous thrombosis. Factor V Leiden is the most common genetic risk factor for venous thrombosis and pulmonary embolism. It is present in 5% of the Caucasian population and in 20% to 40% of individuals with a history of venous thromboembolism. Not all individuals who are heterozygous for factor V Leiden will experience a thrombotic event, and the factor V R2 DNA analysis identifies some individuals at risk. Factor V Leiden heterozygotes are at a sevenfold increased risk for venous thrombosis compared to the general population. Coexistence of the R2 polymorphism with factor V Leiden increases that risk by an additional threefold, leading to an increased risk of approximately 16-fold.