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Genetics glossary

What is MTHFR?

Also known as: Methylenetetrahydrofolate reductase.
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Quick answer

MTHFR: definition

MTHFR is a gene that encodes the enzyme methylenetetrahydrofolate reductase, which converts folate into its active form (5-MTHF) for homocysteine recycling.

MTHFR, explained

Common variants — C677T (rs1801133) and A1298C (rs1801131) — can reduce enzyme activity. They are very common and are not a diagnosis.

Why it matters

MTHFR is one of the most frequently tested genes in wellness genetics and a key part of the methylation story.

Learn more

Genetics · GuideMTHFR: What the Gene Does, Common Variants and What Results MeanWhat is MTHFR? Learn what the gene does, how common the C677T and A1298C variants are, what results do and don't mean, folic acid vs. methylfolate, and smart next steps.Genetics · GuideMethylation: What It Is, Why It Matters and How to Support ItWhat is methylation? A plain-English guide to the methylation cycle, the nutrients that power it (folate, B12, B6, choline), related genes like MTHFR and COMT, and how to support it.Genetics · ArticleMTHFR C677T vs. A1298C: What the Two Common Variants MeanHow the two common MTHFR variants differ, what heterozygous, homozygous and compound heterozygous mean, and practical next steps to discuss.

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FAQ

MTHFR FAQs

What is MTHFR?

MTHFR is a gene that encodes the enzyme methylenetetrahydrofolate reductase, which converts folate into its active form (5-MTHF) for homocysteine recycling.

Why does MTHFR matter?

MTHFR is one of the most frequently tested genes in wellness genetics and a key part of the methylation story.

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