The MTHFR gene and its Function The MTHFR gene begins the methylation process as it is responsible for producing the MTHFR. This enzyme metabolises folic acid into 5-methyltetrahydrofolate (5-MTHF) which is this vitamins active form. 5-MTHF converts the amino acid homocysteine down into another essential amino acid called methionine, which is used by your body … Continue reading MTHFR Mutation