What does MTHFR mean on a genetic test?

If you've taken a DNA wellness test, there's a good chance you've seen "MTHFR" on your report — and maybe felt alarmed. Here's what it actually means.

What the MTHFR gene does

MTHFR stands for methylenetetrahydrofolate reductase. The enzyme it codes for converts folate into 5-methyltetrahydrofolate, the active form used to turn homocysteine into methionine. That's one step in methylation, a process involved in making and regulating many molecules in the body.

The common variants

Tests usually report two variants:

• C677T: the most studied. Two copies (homozygous) can reduce enzyme activity substantially, and one copy modestly.
• A1298C: has a smaller effect on enzyme activity.

These variants are extremely common. In many populations, a large share of people carry at least one copy of C677T, and roughly 10–15% of some populations carry two copies. MedlinePlus notes that the C677T variant is associated with elevated homocysteine mainly when folate levels are low.

What your result doesn't mean

An MTHFR variant is not a diagnosis. The American College of Medical Genetics and Genomics (ACMG) states that MTHFR testing has minimal clinical utility and recommends against ordering it as part of an evaluation for clotting problems or recurrent pregnancy loss. If homocysteine is the concern, measuring it directly in the blood is more informative.

Practical takeaways

• Eat folate-rich foods: leafy greens, legumes, citrus.
• Make sure you get enough vitamin B12.
• Don't start high-dose supplements based on a variant alone; talk with a clinician first.

Curious about supplement forms? Read methylfolate vs folic acid, and visit our MTHFR hub for a deeper guide.