The Impact of Prothrombotic Mutations on Factor Consumption in Adult Patients with Severe Hemophilia

About 10% of patients with severe hemophilia exhibit a milder clinical phenotype with less frequent bleeds. Among many other factors, coinheritance of prothrombotic mutations have been proposed to act as modulators of clinical severity in severe hemophilia. We conducted a study to evaluate the impact of 3 prothrombotic mutations (factor V Leiden, factor II, and methylenetetrahydrofolate reductase mutations) on clinical phenotype of patients with severe hemophilia in our institution. For this purpose we compared the average annual factor concentrate consumption between carriers and noncarriers of prothrombotic mutations. A total of 38 hemophilia A and B patients with factor levels less than 1 were recruited between October 2006 and October 2007. Prothrombotic mutations were detected in venous blood using polymerase chain reaction amplification technique. Eighteen patients (47%) carried no prothrombotic mutations. The remaining 20 patients (53%) were found to be carriers of either 1 or 2 mutations. Median a...