MTHFR Gene Test
Reviewed
This test checks a sample of your blood for two common changes (variants) in the MTHFR gene, called C677T and A1298C. The MTHFR gene helps your body use folate (a B vitamin) to break down an amino acid called homocysteine. Having one of these gene changes does not necessarily increase your risk for any health condition, nor does it guarantee high homocysteine levels. The test is usually done only if a homocysteine blood test has already shown high levels, or if a newborn has a positive result in a routine homocystinuria screening test. However, many medical experts do not recommend routine testing for these common MTHFR gene changes because treatment for high homocysteine is the same regardless of the cause.
Preparation and collection
You don't need any special preparations for this test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- Having an MTHFR gene variant does not necessarily increase your risk for any health condition, nor does it guarantee that you will have high homocysteine levels.
- Researchers are not certain whether homocysteine levels affect your risk for developing blood clots or early heart or blood vessel disease.
- Because of this uncertainty, some medical experts recommend against using MTHFR testing for this purpose.
- A negative result for common variants does not rule out rare MTHFR gene changes that can cause homocystinuria.
What to do next
If you have questions about your results, talk with your provider. Do not make changes to your health habits without first discussing them with your provider. The U.S. Centers for Disease Control and Prevention (CDC) recommends folic acid supplements for everyone who may become pregnant, even if you have an MTHFR gene variant.