URL of this page: https://medlineplus.gov/lab-tests/mthfr-mutation-test/

MTHFR Mutation Test

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:

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

Your new baby may also get an MTHFR test as part of routine newborn screening. A newborn screening is a simple blood test that checks for a variety of serious diseases.

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.

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.

References

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The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.