Venous thromboembolism in a young woman with combined homozygosity for factor V Leiden and prothrombin G20210A mutations.

Thrombophilia involves genetic and acquired conditions that increase the risk of venous thromboembolism (VTE). During the last decade, the identification of thrombophilic defects has increased from less than 10% to approximately 50% of patients presenting with unprovoked VTE. The factor V Arg506Gln (factor V Leiden) and the prothrombin G20210A mutations are the most prevalent abnormalities, found in 15 to 25% and 6 to 16% of unselected VTE patients, respectively. The severity of thrombophilic defects influences the individual VTE risk, the age at onset of disease and the rate of recurrence. Moreover, the clinical expression may differ between individuals bearing the same genetic background. We report the unusual carriage of double homozygous factor V Leiden and factor II mutations, in a 22-year old woman presenting with an extensive proximal deep venous thrombosis involving left common and external iliac, femoro-politeal and infra-popliteal veins. The only precipitating factor was a third-generation oral contraceptive (Meliane), begun six weeks earlier. No thrombotic event was documented among 5 first-degree relatives. No consanguinity was reported. Upon treatment with low molecular weight heparin relayed by acenocoumarol, the patient recovered uneventfully. No relapse occurred during a two-year observational period, with ongoing anticoagulation. The thrombophilia study revealed homozygosity for both factor V Arg506Gln (Leiden) and prothrombin 20210A mutations; no deficiency of protein C, S or antithrombin was found; plasma homocysteine level was normal; factor VIII-C was moderately increased to 179% of normal value, no antiphospholipid antibodies were found.