Effect of the MTHFRC677T variant on risk of venous thromboembolism: interaction with factor V Leiden and prothrombin (F2G20210A) mutations

Odds ratios for the MTHFR C677T variant were determined in a large case–control study of 558 unselected patients with venous thromboembolism and 500 control subjects. The odds ratios for MTHFR C677T heterozygosity and homozygosity were 1.07 (95%CI 0.84–1.36) and 0.71 (95%CI 0.48–1.03). In patients with the factor V Leiden or the F2 G20210A mutations there was no apparent increase in risk of venous thromboembolism due to the MTHFR C677T polymorphism.
Thrombophilia testing should not include genotyping for the MTHFR C677T polymorphism.