Contribution of the glycoprotein Ia 807TT, methylene tetrahydrofolate reductase 677TT and prothrombin 20210GA genotypes to prothrombotic risk among factor V 1691GA (Leiden) carriers

The cooperative effects of the GPIa 807TT, MTHFR 677TT and prothrombin 2021 0GA genotypes with the FV Leiden 1691GA (FVL) genotype were evaluated by co mparing these genotype frequencies in 77 asymptomatic and 156 symptomatic h eterozygous FVL carriers. The GPIa 807TT and MTHFR 677TT genotypes did not segregate within the symptomatic FVL carrier group and did not contribute t o venous thrombotic risk in this patient cohort. There was no difference in the prothrombin 20210GA genotype frequency between asymptomatic FVL carrie rs and a random Caucasian control group; however, the prothrombin 20210GA g enotype was nearly 5 times as prevalent (19/156 v 2/77; P < 0.02) in the sy mptomatic FVL carriers (odds ratio 5.21: 95% confidence interval 1.20-47.62 ), demonstrating that this important prothrombotic risk factor acts synergi stically with FVL.