MTHFR and deep vein thrombosis: Increased hyperhomocysteinemia (sometimes be related with MTHFR mutations) seems to be responsible for increased risk of thrombosis.7 The homozygote polymorphism of MTHFR (C677T) is the most common hereditary defect of the remethylation process.8 The coherence of these findings probably supports that hyperhomocysteinemia is clinically significant in venous thrombosis.5