Risk factors for clinical manifestation in carriers of Factor V Leiden and prothrombin gene mutations

Background. Carriers of Factor V Leiden (FVL) and prothrombin G20210A gene mutations (PGM) have an increased risk of developing thromboembolic events and adverse outcomes of pregnancy.;Objective. To identify risk factors which may predispose carriers of FVL and/or PGM to develop thromboembolic events and adverse outcomes of pregnancy.;Methods. Retrospective case control study of 217 carriers of FVL and/or PGM at two tertiary centers between January 2000 and December 2006. Symptomatic carriers (cases) were compared with asymptomatic carriers (controls) for the following risk factors: environmental, cardiovascular, family history of thrombosis and presence of other thrombophilias. For female carriers, we included the use of female hormones, pregnancy, and the post-partum period.;Results. Of the 217 carriers, there were 155 (71%) cases and 62 (29%) controls. Of the 155 cases, 90 (58%) had venous thrombosis and 26 (17%) arterial thrombosis. Among the 123 symptomatic female carriers, 55 (45%) had recurrent pregnancy losses, and 9 (7%) other adverse outcomes of pregnancy. The postoperative state and the presence of antiphospholipid antibodies (aPLAs) were risk factors for thromboembolic events and adverse outcomes of pregnancy in 10 (6%) and 22 (13%) cases, respectively. The presence of aPLAs in symptomatic carriers increased the risk of developing thromboembolic events 4.4-fold.;Conclusions. The postoperative state and the presence of aPLAs were significant risk factors for thromboembolic events and adverse outcomes of pregnancy among FVL and/or PGM carriers. Testing for the presence of aPLAs may be warranted in FVL and/or PGM carriers who develop these adverse clinical manifestations.;Key words. case-control study; hereditary thrombophilia FVL; PGM, risk factors; aPLAs; venous thrombosis; arterial thrombosis; recurrent pregnancy loss.