Marburg I polymorphism of factor VII-activating protease and risk of recurrent venous thromboembolism.

Whether a single nucleotide polymorphism (1601 G > A) in the factor VII-activating protease gene (FSAP Marburg I) is a risk factor for venous thromboembolism (VTE) is unclear. We investigated the relevance of the variant with respect to recurrentVTE. 854 patients with a first unprovoked VTE were followed for an average of 41 months after discontinuation of anticoagulation. Study endpoint was symptomatic recurrent VTE. VTE recurred in 7 of 41 patients (17%) with and in 106 of 813 patients (13%) without the variant. After 3 years, the probability of recurrence was 20.0% (95% CI, 5.3% to 34.6%) among patients with and 12.2% (95% CI, 9.6% to 14.8%) among those without FSAP Marburg I (p = 0.5). The relative recurrence risk among carriers of the variant was 1.3 (95% CI, 0.6 to 2.8; p = 0.5) before and 1.5 (95% CI, 0.7 to 3.3; p = 0.3) after adjustment for potentially confounding factors. We conclude that FSAP Marburg I is, if at all, only a mild factor for recurrent VTE. Patients with FSAP Marburg I most probably will not benefit from extended anticoagulation.