The MTHFR gene provides instructions for making an enzyme called methylenetetrahydrofolate reductase. This enzyme plays a role in processing amino acids, the building blocks of proteins. Methylenetetrahydrofolate reductase is important for a chemical reaction involving the vitamin folate (also called vitamin B9).
The MTHFR (methylenetetrahydrofolate reductase) gene produces an enzyme involved in the processing of folate and regulation of homocysteine in the body. Folate is a critical nutrient involved in methylation, DNA synthesis, and amino acid metabolism. Impaired folate metabolism due to MTHFR enzyme inactivity or a low folate level results in elevated plasma homocysteine. Homocysteine is an amino acid synthesized by the body through demethylation of methionine.
In the presence of adequate B-vitamins, homocysteine is either irreversibly degraded to cysteine or it is remethylated back to methionine, an essential amino acid. An elevated homocysteine level is known to be an independent risk factor for ischemic stroke, thrombotic and cardiovascular diseases. Folate, vitamin B6 and vitamin B12 are all necessary molecules for the proper conversion of homocysteine into methionine. A deficiency in any one of these molecules can cause homocysteine levels to rise.
Genetic Markers Included
The two single nucleotide variants known to affect MTHFR function are the C677T (a change from cytosine to thymine at position 677 within the gene) and A1298C (a change from adenine to cytosine at position 1298 within the gene) mutations. It is not uncommon for some individuals to have both MTHFR variants.
Clinical relevance is associated with homozygosity for either C677T or A1298C, and the compound heterozygous state (presence of both heterozygous alleles C677T/ A1298C). In general, these variants produce an MTHFR enzyme with reduced function and activity.
Reduced functionality of MTHFR can cause homocysteine levels to escalate, and this issue is intensified with low levels of folate. Genotyping of the MTHFR gene can inform physicians of a patient’s predispositions for elevated homocysteine. Elevated homocysteine is associated with atherosclerosis and blood clots. With this knowledge, physicians can recommend a proper diet and make medical recommendations to help decrease elevated plasma homocysteine.
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