What it measures
A gene test showing whether a person carries the C677T variant of the MTHFR gene, and in how many copies. The gene makes an enzyme the body uses to process folate and homocysteine.
Why people test it
- Checked when homocysteine is raised, since the MTHFR enzyme is part of how the body clears it.
- Asked about by people looking into how their body handles folate.
- Sometimes checked when a relative is known to carry the variant.
Typical range
Reported as a genotype, not a number: no copies of the variant, one copy (heterozygous) or two copies (homozygous). Labs word the result differently, and the report states which variant was read.
Finger-prick or vein?
Offered as a vein draw only. The variant is read from DNA in the blood cells, and the result does not change over a lifetime.
The variant is common, and many people who carry one or two copies have normal homocysteine levels.