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Genetic and Rare Diseases Information Center (GARD)

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Homocysteinemia due to MTHFR deficiency


Other Names for this Disease

  • 5,10 alpha methylenetetrahydro-folate reductase deficiency
  • 5,10-alpha-methylenetetrahydro-folate reductase deficiency
  • Homocysteinemia due to methylenetetrahydro-folate reductase deficiency
  • Homocysteinuria due to methylenetetrahydro-folate reductase deficiency
  • Homocysteinuria due to MTHFR deficiency
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

I have MTHFR deficiency. Can you tell me more about this in lay language?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is homocysteinemia due to MTHFR deficiency?

Homocysteinemia due to MTHFR deficiency is a metabolic condition characterized by neurological problems, such as developmental delay, seizures, and microcephaly. Signs and symptoms of vary from no symptoms to severe neurologic and blood vessel disease. It is inherited in an autosomal recessive fashion and is caused by mutations in the MTHFR gene . These mutations may cause a mild to severe loss of activity of the MTHFR enzyme and result in elevated levels of homocysteine in the blood (homocysteinemia) or urine (homocysteinuria). The most common MTHFR gene mutation is the C677T mutation. Health problems tend not to be related to whether someone has a MTHFR gene mutation or even a MTHFR enzyme deficiency, but whether the deficiency is leading to elevated levels of homocysteine in the blood (homocysteinemia) or urine. [1][2]
Last updated: 7/20/2011

What are the signs and symptoms of homocysteinemia due to MTHFR deficiency?

Symptoms of MTHFR deficiency vary from no symptoms to severe neurologic and blood vessel disease. Health problems tend not to be related to whether someone has a MTHFR gene mutation or even a MTHFR enzyme deficiency, but whether the deficiency is leading to elevated levels of homocysteine in the blood or urine.[3] Elevated levels of homocysteine in the blood can damage the lining of the arteries, which increases the risk of heart disease, including coronary heart disease, and stroke in adults. However, there are many other factors that play a part in determining a person’s risk of heart disease and stroke.[4] And many people with a homocysteinemia may never have any symptoms or adverse complications.[4]

High homocysteine levels in the blood may also increase the risk of preeclampsia, miscarriage, and blood clots. In general, mild to moderate homocysteinemia has been associated with an increase risk developing blood clots in the veins often in the lower leg or calf, which can travel to the lung (i.e., pulmonary embolism). [5]
Last updated: 7/20/2011

What causes homocysteinemia due to MTHFR deficiency?

Homocysteinemia due to MTHFR deficiency is caused by mutations in the MTHFR gene, which provides the instructions for making an enzyme called MTHFR. MTHFR  is important for a chemical reaction in the body involving forms of the vitamin called folate.   A change or mutation in the MTHFR gene may result in an enzyme that doesn't work like it should. Once the MTHFR enzyme has finished its work on the folate, the folate is ready to be used in the body. One of its jobs it to process a chemical called homocysteine, changing it to methionine which is used for making proteins and other important compounds.[4] 

There are many different gene mutations that can occur in the MTHFR gene that can result in a MTHFR enzyme that is not working as it should. The most common MTHFR gene mutation is the C677T mutation.[4]
Last updated: 7/20/2011

How is homocysteinemia due to MTHFR deficiency inherited?

This condition is inherited in an autosomal recessive fashion, which means that both copies of the gene in each cell have mutations in the MTHFR gene. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.[3]
Last updated: 7/20/2011

Is genetic testing available for homocysteinemia due to MTHFR deficiency?

Genetic testing for homocysteinemia due to MTHFR deficiency is available. It should be noted that health problems tend not to be related to whether someone has a MTHFR gene mutation or even a MTHFR enzyme deficiency, but whether the deficiency is leading to elevated levels of homocysteine in the blood (homocysteinemia) or urine. GeneTests lists the names of laboratories that are performing clinical genetic testing for MTHFR deficiency. To view the contact information for the clinical laboratories conducting testing click here.

Please note: Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.
Last updated: 1/11/2011

How might homocysteinemia due to MTHFR deficiency be treated?

The optimal treatment for people with homocysteinemia due to MTHFR deficiency is unknown.  Studies of treatment with folic acid, vitamin B6, and vitamin B12 supplementation have been reported; however the benefit of this treatment is unclear. While vitamin therapy can reduce the levels of homocysteine, the evidence that these lower levles are associated with a reduction in the risk of complications due to homocysteinemia is lacking. Much of the literature on this topic is conflicting, with some studies reporting benefit, some no improvement, and some an increased risk for complications.[5][6]
Last updated: 7/20/2011

How can I find a genetics professional in my area?

Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:

Last updated: 1/21/2014

References
Other Names for this Disease
  • 5,10 alpha methylenetetrahydro-folate reductase deficiency
  • 5,10-alpha-methylenetetrahydro-folate reductase deficiency
  • Homocysteinemia due to methylenetetrahydro-folate reductase deficiency
  • Homocysteinuria due to methylenetetrahydro-folate reductase deficiency
  • Homocysteinuria due to MTHFR deficiency
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.