Methylenetetrahydrofolate reductase MTHFR , polymorphisms

Fisher MC, Cronstein BN (2009) Metaanalysis of methylenetetrahydrofolate reductase (MTHFR) polymorphisms affecting methotrexate toxicity. J Rheumatol 36 539-545... 

Weisberg I, et al, A second genetic polymorphism in methylenetetrahydrofolate reductase (MTHFR) associated with decreased enzyme activity. Mol Genet Metab 1998 64(3) 169-172. 

Methylenetetrahydrofolate reductase is an approximately 19,301 base pair gene with 11 exons and located on chromosome lp36.3 (2). Multiple polymorphic sites have been described, with the C677T and A1298G most often studied. As expected, allele frequency data varies by ethnicity The MTHFR C677T variant allele is present in 34% of Caucasians, 20% of Italians and Hispanics, 14% of African-Americans, and <1 % of Africans (3,4). The MTHFR A1298G allele is present in n%-36% of Western Europeans (4). 

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