What does the MTHFR test look for?
It looks for the two most common changes in a gene called MTHFR. MedlinePlus explains that the gene makes a protein that helps your body use folate, a B vitamin, to break down an amino acid called homocysteine. The test checks for two variants, C677T and A1298C, and reports whether you carry none, one copy or two copies of each.
These variants are common. MedlinePlus Genetics estimates that about 25 percent of Hispanic people and 10 to 15 percent of North American white people carry two copies of C677T. The C677T change makes the enzyme less stable at higher temperatures, so it works less efficiently. There is no numeric range: the result is a genotype, and because it is inherited, it never changes.
What does each result mean?
The meaning depends on how many copies you carry and which ones. This is how MedlinePlus reads the main combinations:
| Your result | What it means | Usual next step |
|---|---|---|
| No variants found | Neither common MTHFR change is present | If homocysteine is high, look for other causes |
| One copy of C677T or A1298C | Unlikely to cause any health problems | Usually nothing changes |
| Two copies of A1298C | Probably not the reason for a high homocysteine | Look for other causes if homocysteine is high |
| Two copies of C677T, or one C677T plus one A1298C | Probably explains a high homocysteine, if one is found | Check homocysteine |
The other causes MedlinePlus lists for a high homocysteine include a lack of B vitamins, certain medicines, older age, an underactive thyroid and kidney disease. Those are usually easier to find and fix than the gene, which is why the gene result rarely stands alone.
Why does a two-copy result lead to a homocysteine check?
Because the variant only matters through what it does to homocysteine. MedlinePlus Genetics notes that people with the C677T change, especially in both copies, have higher homocysteine, and that two copies have been linked to a higher risk of vascular disease, including heart disease and stroke. Measuring homocysteine tells you whether that is actually happening in your body.
If homocysteine is normal, a two-copy result has done its work by prompting the check, and there is nothing to treat. If it is high, MedlinePlus explains that treatment is the same whether or not MTHFR is the cause: B vitamins that include folic acid, with methylfolate sometimes used instead for people with the variant. Your provider makes that choice and sets any dose. Our homocysteine blood test page covers the other causes and what lowering it does and does not do, and the folate blood test page covers the vitamin side.
What do genetics experts say about testing?
They are skeptical of routine MTHFR testing. The American College of Medical Genetics and Genomics concluded that MTHFR testing has minimal clinical utility and should not be ordered as part of a routine evaluation for blood clotting disorders. The same guideline notes that meta-analyses have disproven a link between MTHFR status and venous blood clots, and between mildly raised homocysteine and coronary heart disease risk.
MedlinePlus reflects that caution, saying medical experts do not recommend testing for common MTHFR changes in most cases. It describes narrower reasons to test: a high homocysteine plus a close relative with an MTHFR change, early heart or blood vessel disease in you or your family, or a plan to take methotrexate. That is the fair way to read your result: useful context, not a diagnosis or a forecast.
How Ultimate Male reads an MTHFR result
MTHFR is part of our Cancer Risk Insight Panel, alongside HLA-B27 with optional BRCA screening, described on the genetic risk screening panel page. It is also on the published marker list for our comprehensive panel, which includes homocysteine, folate and B12, so a two-copy result can be checked against your actual homocysteine from the same on-site draw at San Gabriel or Downey.
At the review, a PA-C or MD explains what your genotype does and does not mean, and whether homocysteine or folate needs attention. The HLA-B27 test page explains the other marker on the panel, and our overview of whether a genetic risk panel makes sense for men helps you decide if it is worth doing at all. All options are listed on our preventative blood testing page.
