MTHFR (Methylenetetrahydrofolate Reductase): MTHFR is a gene that helps your body process folate (vitamin B9) and homocysteine, which are important for cell health, DNA production, and heart and brain health. Normal MTHFR function supports healthy metabolism of folate and homocysteine. MTHFR gene variations (mutations) can affect how efficiently your body processes these nutrients, which may increase homocysteine levels, potentially impacting cardiovascular health, mood, fertility, and detoxification.