The Risk of Recurrent Deep Venous Thrombosis among Heterozygous Carriers of Both Factor V Leiden and the G20210A Prothrombin Mutation

Inherited resistance to activated protein C is a thrombophilic condition resulting from a mutant factor V (factor V Leiden). 1 The mutation is relatively common among whites, with a frequency of 5 percent in the general population of European ancestry and 11 to 21 percent among patients with venous thromboembolism. 2 The estimated risk of deep venous thrombosis is 7 times as high among heterozygous carriers of the mutation as among persons without the mutation, and 80 times as high among homozygotes. 3 There is disagreement whether factor V Leiden is associated with an increased risk of recurrent deep venous thrombosis. Several studies . . .