THE PROTHROMBIN GENE G20210A VARIANT - PREVALENCE IN A UK ANTICOAGULANT CLINIC POPULATION

We have investigated the prevalence of a recently reported genetic var iation in the prothrombin gene (G20210A) in patients with an objective ly confirmed history of venous thrombosis. 12/219 patients (5.5%) were found to be heterozygous carriers of the 20210 A allele. The incidenc e of the 20210 A allele in a group of 164 healthy controls was 1.2% (a llele frequency 0.61%, 95% CI 0.08-2.19). When patients with a known a lternative hereditary risk factor for venous thrombosis (factor V Leid en mutation or deficiency of antithrombin, protein C or protein S) wer e excluded, the G20210A variant was found to increase the risk for ven ous thrombosis by approximately 5-fold (odds ratio 5.4, 95% CI 1.16-25 .0). This prothrombin gene sequence variation adds further to the list of recognized genetic risk factors for thrombophilia.