I have recently been diagnosed with the C677T heterozygous gene mutation. What I would most like to know is: does this mutation have any bearing or is it something I do not need to concern myself with?
MTHFR is a gene. We all carry two copies of MTHFR. MTHFR tells our body how to create an enzyme involved in breaking down the amino acid homocysteine. As is true for any gene, the DNA code of the MTHFR gene can vary. When we identify a part of the sequence that varies, we call it a "variant." Genetic research aims to identify specific variants that cause harm or benefit to health.
There are two MTHFR gene variants, called C677T and A1298C, that have been an active area of study. These variants are common. In America, about 25% of people who are Hispanic, and 10-15% of people who are Caucasian have two copies of C677T.
Studies have found that women with two C677T gene variants have an increased risk for having a child with a neural tube defect. Studies have also found that men and women with two C677T gene variants and elevated homocysteine levels may be at a mild increased risk for blood clots (venous thromboembolism).
Very high homocysteine levels rarely result from having two common variants alone. People with very high homocysteine levels should be carefully evaluated for other factors known to affect homocysteine. Doing so may bring to light dietary deficiencies, thyroid disease, diabetes, high cholesterol, or life-style factors (physical inactivity, smoking and obesity) which can impact homocystine levels. If high levels of homocysteine cannot be explained by these factors, a consultation with a genetics professional may be helpful in identifying rare genetic causes of the high homocysteine. To learn more about rare genetic causes, visit: Homocystinuria due to MTHFR Deficiency.
Last updated: 1/25/2018
Does having one C677T mutation in the MTHFR gene increase a person's risk of developing blood clots?
Having one mutation in the MTHFR gene is typically not associated with an increased risk of blood clots, because it usually does not lead to high levels of homocysteine in the blood.
Liew SC & Gupta ED. Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism: epidemiology, metabolism and the associated diseases. Eur J Med Genet. January 2015; 58(1):1-10. https://www.ncbi.nlm.nih.gov/pubmed/25449138.
Wilcken B & cols. Geographical and ethnic variation of the 677C>T allele of 5,10 methylenetetrahydrofolate reductase (MTHFR): Findings from over 7000 newborns from 16 areas world wide. J Med Genet 2003; 40(8):619–25. https://www.ncbi.nlm.nih.gov/pubmed/12920077.