MTHFR Gene Test
Reviewed
Also called: methylenetetrahydrofolate reductase mutation, C677T and A1298C, MTHFR DNA assay, MTHFR DNA testing, MTHFR gene variants, MTHFR gene polymorphisms 677T>C & 1298A>C mutations
An MTHFR gene test checks a sample of your blood for two very common changes in a gene called MTHFR.
Specimen: blood
Why this test may be ordered
- You had a blood test showing higher than normal homocysteine levels and a close relative was diagnosed with an MTHFR gene change.
- You had a blood test showing higher than normal homocysteine levels and you and/or close family members have early heart or blood vessel disease.
- Your provider prescribes methotrexate (used for certain cancers, psoriasis, or rheumatoid arthritis) and wants to choose a safe dose.
- A newborn has a positive result in a routine homocystinuria screening test.
Preparation and collection
You don't need any special preparations for an MTHFR gene test.
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
The results of an MTHFR gene test tell you whether you have one or both of the two most common changes in the MTHFR gene.
- Positive: A positive test result means that you have an MTHFR gene change in one or both of your MTHFR genes. Limitation: Having a change in only one of your MTHFR genes is unlikely to cause any health problems. Next step: Before making changes in your health habits, talk with your provider.
- Negative: A negative test result means that neither of the common MTHFR gene changes were found in your blood sample. Limitation: If you have an increased homocysteine level, it's probably from another condition, such as a lack of B vitamins, taking certain medicines, older age, hypothyroidism, kidney disease, or another disease. Next step: If you have questions about your results, talk with your provider.
- 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.
- What do my MTHFR test results mean for my health?
- Do I need a homocysteine blood test?
- Should I take vitamin B supplements, and if so, which type?
- How often should I have my homocysteine levels checked?
- Do I need to see a genetic counselor?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.