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Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test

Last updated May 9, 2019

Approved by: Krish Tangella MD, MBA, FCAP

The Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test is a test to detect the presence of an MTHFR mutation from blood cells. It is used to evaluate the cause of elevated homocysteine levels and assess the risk for cardiovascular disease.


What are the other Names for this Test? (Equivalent Terms)

  • MTHFR Blood Test
  • MTHFR DNA Blood Test

What is Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test? (Background Information)

  • Methylenetetrahydrofolate reductase (MTHFR) is an enzyme needed for amino acid conversion and vitamin B9 metabolism. It is susceptible to mutations, which can hinder its function and cause adverse effects
  • One of the functions of MTHFR enzyme is to chemically modify a protein, in order to prepare it for entering the methionine-homocysteine cycle. This cycle is important for amino acid metabolism
  • If MTHFR were unable to fulfill this function, the levels of homocysteine would accumulate. At high levels, homocysteine causes damage to the inner lining of blood vessels. This may increase the risk for cardiovascular disease
  • Another process in which MTHFR is needed involves the metabolism of folate, or vitamin B9. Generally, different types of B vitamins are essential for energy production and the production of intermediates, needed in other important pathways
  • The instructions for producing MTHFR are encoded on the MTHFR gene. Mutations in this gene may lead to the production of defective MTHFR enzyme. This may impair amino acid conversion and vitamin B9 metabolism
  • The Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test is a test to detect the presence of an MTHFR mutation from blood cells. It is used to evaluate the cause of elevated homocysteine levels and assess the risk for cardiovascular disease

What are the Clinical Indications for performing the Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test?

Following are the clinical indications for performing a Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test:

  • Following-up to a finding of elevated homocysteine levels
  • Family history of cardiovascular disease or MTHFR mutation

How is the Specimen Collected for Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test?

Following is the specimen collection process for Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected, by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the Methylenetetrahydrofolate Reductase Mutations C677T and A1298C Blood Test Result?

There are two common mutations in MTHFR, which are C677T and A1298C. These vary in significance:

  • Two copies of MTHFR C677T, or one copy of MTHFR C677T and one of A1298C, are strongly associated with elevated homocysteine levels
  • Two copies of MTHFR A1298C are not associated with elevated homocysteine levels

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.  

Additional and Relevant Useful Information:

  • MTHFR mutations are also associated with neural tube defects and pre-eclampsia. However, these associations are not definitive

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 4, 2015
Last updated: May 9, 2019