MTHFR Gene Test
An MTHFR gene test identifies common genetic variants that may affect how your body processes folate, potentially influencing homocysteine levels.
What is an MTHFR gene test?
An MTHFR gene test checks a sample of your blood for two very common changes in a gene called MTHFR. Changes in your genes are also called gene variants or mutations.
Genes are parts of DNA in your cells that you inherit from your parents. You inherit two copies of each gene, one coming from each parent. The MTHFR gene provides instructions for making the MTHFR protein. This protein helps your body use folate, a type of B vitamin. Normally, your body uses folate and other B vitamins to break down an amino acid called homocysteine. If you have a change in the MTHFR gene, the protein may not process folate as well as it should, which may result in increased levels of homocysteine in your blood.
Health Implications
While medical researchers are not certain that increased homocysteine levels directly cause health problems, some studies suggest they can damage the inside of blood vessels, potentially increasing the risk for blood clots, heart disease, and stroke. Higher homocysteine levels during pregnancy can increase the risk of:
- A baby with neural tube defects.
- Early pregnancy loss (a miscarriage).
- Preeclampsia.
What is it used for?
The test looks for the two most common MTHFR gene variants: C677T and A1298C. Having these variants does not guarantee high homocysteine levels or health conditions. Providers may order this test if a homocysteine blood test has already shown high levels to determine if these variants are the cause, or to estimate risks for blood clots or heart disease in those with a family history.
However, many experts recommend against using MTHFR testing for these purposes because the treatment for high homocysteine is the same regardless of the cause, and the link between these specific variants and heart disease remains uncertain.
Why do I need an MTHFR gene test?
Medical experts generally do not recommend testing for common MTHFR changes. However, a provider may order it if you have high homocysteine levels and:
- A close relative was diagnosed with an MTHFR gene change.
- You or close family members have early heart or blood vessel disease.
- You are prescribed the medicine methotrexate, as the MTHFR protein helps your body use this drug properly.
What happens during an MTHFR gene test?
A health care professional will take a blood sample from a vein in your arm using a small needle. The process typically takes less than five minutes.
What do the results mean?
- Positive result: You have an MTHFR gene change in one or both genes. Having a change in only one gene is unlikely to cause health problems. If you have high homocysteine, having two copies of C677T or one copy each of C677T and A1298C suggests these variants are likely the cause.
- Negative result: Neither of the common MTHFR gene changes were found. High homocysteine levels in this case are likely due to other factors, such as lack of B vitamins, older age, or other medical conditions.