5,10-methylenetetrahydrofolate reductase (MTHFR) catalyses the irreversible reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate (5-MTHF),[2, 3] the primary form of folate.[4] This conversion produces a methyl donor for the conversion of homocysteine to methionine[5] and S-adenosylmethionine …show more content…
Some individuals have a genetic mutation in one or both of their MTHFR genes. Individuals with mutations in one MTHFR gene are called “heterozygous” for the MTHFR mutation. Whereas, a person is “homozygous” for the mutation when mutations are present in both genes.[9] There is also compound heterozygous, where there is one mutated allele on both the 677 and 1298 base position. C677T and A1298C are the most commonly occurring MTHFR polymorphisms. The C677T polymorphism results in a substitution of cytosine (C) to thymine (T) at nucleotide position 677, consequently leading to a substitution of alanine for valine in the N-terminal catalytic domain of the protein.[10] In patients with C677T polymorphism, homozygotes have 30% enzyme activity, while heterozygotes have 65% of MTHFR enzyme activity.[11] The prevalence of C677T homozygote varies between populations, ethnicity and geographic location with the highest prevalence (>20%) found among US Hispanics, Colombians, and Amerindians in Brazil. The prevalence ranges from 8-20% in Europe, North America, United Kingdom, Canada, Japan, and Australia.[5]. In Black populations, there is less than 2% prevalence of MTHFR C677T.[11] Furthermore, a Japanese study found a lower frequency of homozygote MTHFR C677T among those over 80 years (7%) compared with those aged between 55-79 years (14%) and 14-55 years