What is MTHFR? Why This Gene Matters for Your Health

If you have spent any time looking into genetic health, you have probably encountered the gene MTHFR. It stands for methylenetetrahydrofolate reductase -- a mouthful, but the concept is straightforward.

What does MTHFR do?

MTHFR produces an enzyme that converts folate (vitamin B9) into its active form, methylfolate. Methylfolate is essential for a process called methylation, which affects DNA repair, neurotransmitter production, detoxification, and dozens of other cellular processes.

The key variants

Two SNPs (single nucleotide polymorphisms) in the MTHFR gene are the most studied:

• C677T (rs1801133): The most researched variant. Having two copies of the T allele (TT homozygous) can reduce enzyme activity by up to 70%. This is found in roughly 10-15% of certain populations.
• A1298C (rs1801131): A second variant that can also reduce enzyme activity, though typically less dramatically than C677T.

Why it matters

Reduced MTHFR activity can lead to elevated homocysteine levels, which research has linked to cardiovascular risk, pregnancy complications, and mood disorders. People with reduced function variants may benefit from supplementing with methylfolate instead of folic acid, though you should always discuss this with a healthcare provider.

What GenomeHack tells you

When you upload your raw DNA data, GenomeHack checks your MTHFR variants and provides a clear explanation of your genotype, what the research says, and practical considerations. It is one of the markers included in every free DNA Snapshot report.