Common C677T Polymorphism of the Methylenetetrahydrofolate Reductase Gene and the Risk of Venous Thromboembolism: Meta-Analysis of 31 Studies

The classic MTHFR C677T gene polymorphism is weakly associated with an increased risk of VTE. It is unlikely that the purported relationship between hyperhomocysteinemia and VTE is mediated by this gene defect to a substantial degree, although other undiscovered gene polymorphisms may explain this association. Until more compelling data are made available, we do not recommend that testing for the MTHFR C677T polymorphism be routinely included as part of any clinical thrombophilia assessment.