What is an MTHFR mutation test?
This test looks for mutations (changes) in a gene called MTHFR. Genes are the basic units of heredity passed down from your mother and father.
Everyone has two MTHFR genes, one inherited from your mother and one from your father. Mutations can occur in one or both MTHFR genes. There are different types of MTHFR mutations. An MTHFR test looks for two of these mutations, also known as variants. The MTHFR variants are called C677T and A1298C.
The MTHFR gene helps your body break down a substance called homocysteine. Homocysteine is a type of amino acid, a chemical your body uses to make proteins. Normally, folic acid and other B vitamins break down homocysteine and change it into other substances your body needs. There should then be very little homocysteine left in the bloodstream.
If you have an MTHFR mutation, your MTHFR gene may not work right. This may cause too much homocysteine to build up in the blood, leading to various health problems, including:
- Homocystinuria, a disorder that affects the eyes, joints, and cognitive abilities. It usually starts in early childhood.
- An increased risk of heart disease, stroke, high blood pressure, and blood clots
In addition, women with MTHFR mutations have a higher risk of having a baby with one of the following birth defects:
- Spina bifida, known as a neural tube defect. This is a condition in which the bones of the spine do not completely close around the spinal cord.
- Anencephaly, another type of neural tube defect. In this disorder, parts of the brain and/or skull may be missing or deformed.
You can reduce your homocysteine levels by taking folic acid or other B vitamins These can be taken as supplements or added through dietary changes. If you need to take folic acid or other B vitamins, your health care provider will recommend which option is best for you.
Other names: plasma total homocysteine, methylenetetrahydrofolate reductase DNA mutation analysis
What is it used for?
This test is used to find out if you have one of two MTHFR mutations: C677T and A1298C. It is often used after other tests show you have higher than normal homocysteine levels in the blood. Conditions such as high cholesterol, thyroid disease, and dietary deficiencies can also raise homocysteine levels. An MTHFR test will confirm whether the raised levels are caused by a genetic mutation.
Even though an MTHFR mutation brings a higher risk of birth defects, the test is not usually recommended for pregnant women. Taking folic acid supplements during pregnancy can greatly reduce the risk of neural tube birth defects. So most pregnant women are encouraged to take folic acid, whether or not they have an MTHFR mutation.
Why do I need an MTHFR mutation test?
You may need this test if:
- You had a blood test that showed higher than normal levels of homocysteine
- A close relative was diagnosed with an MTHFR mutation
- You and/or close family members have a history of premature heart disease or blood vessel disorders
What happens during an MTHFR mutation 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.
For a newborn screening, a health care professional will clean your baby's heel with alcohol and poke the heel with a small needle. He or she will collect a few drops of blood and put a bandage on the site.
Testing is most often done when a baby is 1 to 2 days old, usually in the hospital where he or she was born. If your baby wasn't born in the hospital or if you have left the hospital before the baby could be tested, talk to your health care provider about scheduling testing as soon as possible.
Will I need to do anything to prepare for the test?
You don't need any special preparations for an MTHFR mutation test.
Are there any risks to the test?
There is very little risk to you or your baby with MTHFR testing. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Your baby may feel a little pinch when the heel is poked, and a small bruise may form at the site. This should go away quickly.
What do the results mean?
Your results will show whether you are positive or negative for an MTHFR mutation. If positive, the result will show which of the two mutations you have, and whether you have one or two copies of the mutated gene. If your results were negative, but you have high homocysteine levels, your health care provider may order more tests to find out the cause.
Regardless of the reason for high homocysteine levels, your health care provider may recommend taking folic acid and/or other vitamin B supplements, and/or changing your diet. B vitamins can help bring your homocysteine levels back to normal.
If you have questions about your results, talk to your health care provider.
Learn more about laboratory tests, reference ranges, and understanding results.
Is there anything else I need to know about an MTHFR mutation test?
Some health care providers choose to only test for homocysteine levels, rather than doing a MTHFR gene test. That is because treatment is often the same, whether or not high homocysteine levels are caused by a mutation.
- Cleveland Clinic [Internet]. Cleveland (OH): Cleveland Clinic; c2018. A Genetic Test You Don't Need; 2013 Sep 27 [cited 2018 Aug 18]; [about 4 screens]. Available from: https://health.clevelandclinic.org/a-genetic-test-you-dont-need
- Huemer M, Kožich V, Rinaldo P, Baumgartner MR, Merinero B, Pasquini E, Ribes A, Blom HJ. Newborn screening for homocystinurias and methylation disorders: systematic review and proposed guidelines. J Inherit Metab Dis [Internet]. 2015 Nov [cited 2018 Aug 18]; 38(6): 1007–1019. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4626539
- Jha S, Kumar P, Kumar R, Das A. Effectiveness of add-on l-methylfolate therapy in a complex psychiatric illness with MTHFR C677 T genetic polymorphism. Asian J Psychiatr [Internet]. 2016 Aug [cited 2020 May 20]; 22:74-5. Available from: https://pubmed.ncbi.nlm.nih.gov/27520898/?from_term=Das+A&from_cauthor_id=27520898&from_pos=1
- Kids Health from Nemours [Internet]. The Nemours Foundation; c1995–2018. Newborn Screening Tests; [cited 2018 Aug 18]; [about 3 screens]. Available from: https://kidshealth.org/en/parents/newborn-screening-tests.html?ref=search&WT.ac=msh-p-dtop-en-search-clk
- Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2018. Homocysteine; [updated 2018 Mar 15; cited 2018 Aug 18]; [about 2 screens]. Available from: https://labtestsonline.org/tests/homocysteine
- Lab Tests Online [Internet]. Washington D.C.; American Association for Clinical Chemistry; c2001–2018. MTHFR Mutation; [updated 2017 Nov 5; cited 2018 Aug 18]; [about 2 screens]. Available from: https://labtestsonline.org/tests/mthfr-mutation
- March of Dimes [Internet]. White Plains (NY): March of Dimes; c2018. Newborn Screening Tests For Your Baby; [cited 2018 Aug 18]; [about 3 screens]. Available from: https://www.marchofdimes.org/baby/newborn-screening-tests-for-your-baby.aspx
- Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2018. Test ID: MTHFR: 5,10-Methylenetetrahydrofolate Reductase C677T, Mutation, Blood: Clinical and Interpretive; [cited 2018 Aug 18]; [about 4 screens]. Available from: https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/81648
- Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2018. Homocystinuria; [cited 2018 Aug 18]; [about 2 screens]. Available from: https://www.merckmanuals.com/home/children-s-health-issues/hereditary-metabolic-disorders/homocystinuria
- National Cancer Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; NCI Dictionary of Cancer Terms: gene; [cited 2018 Aug 18]; [about 3 screens]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/search?contains=false&q=gene
- National Center for Advancing Translational Sciences: Genetic and Rare Diseases Information Center [Internet]. Gaithersburg (MD): U.S. Department of Health and Human Services; Homocystinuria due to MTHFR deficiency; [cited 2018 Aug 18]; [about 2 screens]. Available from: https://rarediseases.info.nih.gov/diseases/2734/homocystinuria-due-to-mthfr-deficiency
- National Center for Advancing Translational Sciences: Genetic and Rare Diseases Information Center [Internet]. Gaithersburg (MD): U.S. Department of Health and Human Services; MTHFR gene variant; [cited 2018 Aug 18]; [about 2 screens]. Available from: https://rarediseases.info.nih.gov/diseases/10953/mthfr-gene-mutation
- NIH U.S. National Library of Medicine: Genetics Home Reference [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; MTHFR gene; 2018 Aug 14 [cited 2018 Aug 18]; [about 3 screens]. Available from: https://ghr.nlm.nih.gov/gene/MTHFR
- NIH U.S. National Library of Medicine: Genetics Home Reference [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; What is a gene mutation and how do mutations occur?; 2018 Aug 14 [cited 2018 Aug 18]; [about 3 screens]. Available from: https://ghr.nlm.nih.gov/primer/mutationsanddisorders/genemutation
- National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests; [cited 2018 Aug 18]; [about 3 screens]. Available from: https://www.nhlbi.nih.gov/health-topics/blood-tests
- Quest Diagnostics [Internet]. Quest Diagnostics; c2000–2017. Test Center: Methylenetetrahydrofolate Reductase (MTHFR), DNA Mutation Analysis; [cited 2018 Aug 18]; [about 3 screens]. Available from: https://www.questdiagnostics.com/testcenter/TestDetail.action?ntc=17911&searchString=MTHFR
- Varga EA, Sturm AC, Misita CP, and Moll S. Homocysteine and MTHFR Mutations: Relation to Thrombosis and Coronary Artery Disease. Circulation [Internet]. 2005 May 17 [cited 2018 Aug 18]; 111(19): e289–93. Available from: https://www.ahajournals.org/doi/10.1161/01.CIR.0000165142.37711.E7
- Wan L, Li Y, Zhang Z, Sun Z, He Y, Li R. Methylenetetrahydrofolate reductase and psychiatric diseases. Transl Psychiatry. [Internet]. 2018 Nov 5 [cited 2020 May 20]; 8(1):242. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6218441