Summary

The results concerning the risk of recurrent venous thromboembolism(VTE) in carriers of the G1691A mutation in the coagulationfactor V gene are not consistent and this risk in carriers of the G20210Apolymorphism in the prothrombin gene has hitherto not been reported.We followed 534 patients for 48 months after their first episode ofobjectively documented VTE. The prevalence of the G1691A allele in467 (87.5%) of the patients and in 207 controls was 25.3% and 8.2%,respectively, in heterozygote form and 2.4% and 0.5%, respectively, inhomozygote form. The adjusted odds ratio (OR) for the first VTE was4.4 (95% CI 2.6-7.8). The risk of recurrent VTE in heterozygotes wasnot statistically different from non-carriers (17.8% vs 17.6%), with85% power to detect a hazard ratio of 2.35. Homozygotes had a significantlyincreased risk (p = 0.036) of recurrent VTE. The prevalence ofthe G20210A allele in 456 patients and 207 controls was 6.1% and1.4%, respectively. The adjusted OR was 4.6 (95% CI 1.6-19.3) for thefirst VTE in 28 carriers of this polymorphism. The risk of recurrentVTE for these was not statistically different from non-carriers with anOR of 0.9 (95% CI 0.2-2.9).