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Methylenetetrahydrofolate Reductase (MTHFR), DNA Mutation Analysis

Test code(s) 36165, 10078 (NY), 17911X, 17912X (NY)

This is an outdated version of this FAQ. It was effective 09/12/2012 to 05/07/2015.

The current version is available here.

Question 1. What is methylenetetrahydrofolate reductase (MTHFR) DNA mutation analysis, and what conditions are associated with mutations?

MTHFR DNA mutation analysis tests for the presence or absence of two mutations in the MTHFR gene: 677C>T and 1298A>C. Testing for these mutations helps assess whether an individual is at increased risk for hyperhomocysteinemia and thus increased risk for vascular diseases, venous thrombosis, and neural tube defects.

Question 2. Can I test my patient while he/she is anticoagulated with heparin or warfarin?

Yes. This genetic test is performed by extracting DNA from the patient’s leukocytes and then testing that DNA for the presence or absence of two MTHFR gene mutations (677C>T and 1298A>C). Heparin and warfarin are not known to affect this testing methodology.

Question 3. My patient has had recurrent miscarriages. How do I interpret the result of this test  in that context?      

The role of MTHFR mutations in miscarriage is controversial; most evidence shows that MTHFR mutation status does not predict thrombophilia or pregnancy loss in pregnant women.1 Consider investigating the presence or absence of other risk factors.

Question 4. What is the clinical significance of 677C>T mutations?     

Patients who are heterozygous for the 677C>T mutation are unlikely to have hyperhomocysteinemia and are thus unlikely to need any medical treatment based on this single test result. However, patients who are homozygous, ie, those with two copies of the 677C>T mutation, are at greater risk for hyperhomocysteinemia. Measuring the patient’s blood homocysteine level is the best way to assess clinical status to determine if your patient needs treatment.

Question 5. What is the significance of my patient being heterozygous for the 1298A>C mutation?

Patients who are heterozygous for the 1298A>C mutation are not at risk for hyperhomocysteinemia. However, patients who are compound heterozygotes (ie, those who have one copy of 1298A>C on one chromosome and one copy of 677C>T on the other chromosome) may be at risk for hyperhomocysteinemia. Measuring the patient’s blood homocysteine level is the best way to assess clinical status and determine if your patient needs treatment.

Reference

  1. Practice Bulletin no.113: inherited thrombophilias in pregnancy. Obstet Gynecol. 2010:116:212-222.
This FAQ is provided for informational purposes only and is not intended as medical advice. A physician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.

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