Risk of thrombosis in patients with antiphospholipid antibodies and factorV Leiden mutation

Objective. Antiphospholipid antibodies (aPL) are thrombophilic risk markers in patients with systemic lupus erythematosus (SLE) or primary antiphospho lipid syndrome (APS). The risk factors for recurrent venous or arterial thr ombosis and indications for longterm anticoagulation therapy are debated. W e hypothesized that carrying a second thrombophilic defect, factor V Leiden mutation, would increase the risk for thrombosis in patients with aPL. Methods. Seventy-five patients with primary APS and 83 with SLE and aPL wit h or without thrombosis followed at 2 university hospitals were studied. Fa ctor V mutation rate was analyzed in patients and in 200 healthy blood dono rs by polymerase chain reaction analysis. Results. The prevalence of factor V Leiden mutation in patients with SLE an d aPL or primary APS was similar to controls. Patients with deep vein throm bosis or arterial thrombosis did not have a significantly increased rate of factor V mutation compared to controls or to patients with aPL without thr ombosis. Conclusion, Factor V Leiden mutation is not significantly associated with v ein thrombosis in patients with aPL. However, due to the sample size we can not rule out synergy between both factor V Leiden and aPL. A trend toward i ncreased risk for thrombosis was detected in patients with the mutation and this should be analyzed in a larger study.