The G20210A transition in the prothrombin gene and venous thromboembolic disease.

Introduction. - Genetic predisposition to Venous thrombosis can be due to c oagulation inhibitor deficiencies (antithrombin, protein C or protein S) or to activated protein C resistance resulting from factor V Leiden mutation (FV Leiden). Poort et al. recently identified a new polymorphism in the 3'- untranslated region of the prothrombin gene, the G20210A transition (FII G2 0210A), which was found to be associated with an increased risk of venous t hrombosis. Exegesis. - The prevalence of the A allele is approximately 1 to 4% in the general population, and 5 to 7% in patients with venous thrombosis. Heteroz ygous carriers have a three to five limes increased risk of thrombosis. The diagnosis is based on a polymerase chain reaction technique and restrictio n enzyme digestion from genomic DNA. Recent studies aim to determine the re lative risk of thrombosis and the clinical features which are associated wi th the mutation (age of first thrombosis, recurrence). The thrombotic risk seems to be higher when FII G20210A transition is associated with the FV Le iden mutation. Conclusion. - The presence of heterozygous FII G20210A transition does not modify the management of acute thrombotic events but can lead to an increas e in the duration of the anticoagulant treatment. When such a genetic abnor mality is identified, thorough information of the patient is needed.