MTHFR Mutation Genotype

MTHFR is the gene encoding methylenetetrahydrofolate reductase, the enzyme that converts folate into the active form used to clear homocysteine from the blood. This test identifies the two common variants, C677T and A1298C, that reduce enzyme activity and can raise homocysteine, particularly when folate intake is low. The genotype is a risk factor, not a diagnosis: these variants do not independently raise risk of homocysteine-related conditions unless homocysteine is actually elevated, so measuring total plasma homocysteine is the more useful functional marker. The one situation where the genotype directly informs care is folate-dependent chemotherapy such as methotrexate, where sharing your result with the prescribing physician matters. Major guidelines do not recommend testing these variants to evaluate clotting or pregnancy risk, given limited evidence of clinical utility.

No fasting or special preparation is needed. This is a genetic test, so the result is fixed for life and never needs repeating. If you also want to know your actual homocysteine level, which is the marker that shows whether the genotype is having any functional effect, that requires a separate blood test.