Inherited thrombophilia is a genetic tendency to venous thromboembolism (VTE), including deep vein thrombosis (DVT), pulmonary embolism, and cerebral vein thrombosis. Women with inherited thrombophilias are at higher risk of VTE, especially in settings such as during use of estrogen-progestin contraceptives or pregnancy (the risk of VTE is much higher in pregnancy/postpartum than with use of an estrogen-progestin contraceptive ). In making contraceptive choices, women need to balance the risk of VTE associated with use of effective contraception against the risk of VTE associated with an unintended pregnancy resulting from use of less effective contraceptive methods.
Factor V Leiden (FVL) is the most common hereditary risk factor for VTE. In unselected Caucasian patients with an initial symptomatic episode of DVT, 12 to 20 percent will be heterozygous for the FVL mutation compared with approximately 6 percent of asymptomatic controls . The prevalence of FVL heterozygosity in Caucasian American women is about 4.85 percent and is less frequent in Hispanic Americans (2.21 percent), Native Americans (1.25 percent), African Americans (1.23 percent), and Asian Americans (0.45 percent) .
The prothrombin gene mutation (G20210A) is the second most common genetic risk factor for VTE: G20210A heterozygosity is identified in 6 percent of patients with VTE compared with 2 percent of asymptomatic controls; deficiencies in protein S, protein C, and antithrombin account for most of the remaining cases [2,4].
Inherited thrombophilia is discussed in detail separately: