5,10-Methylenetetrahydrofolate reductase polymorphisms and pharmacogenetics: a new role of single nucleotide polymorphisms in the folate metabolic pathway in human health and disease.

Knowledge about the role of folate, a water-soluble B vitamin, and single nucleotide polymorphisms (SNPs) in the folate metabolic pathway in human health and disease has been rapidly expanding. Recently, functionally significant SNPs in 5,10-methylenetetrahydrofolate reductase (MTHFR), a critical enzyme for intracellular folate homeostasis and metabolism, have been identified and characterized. An emerging body of in vitro and clinical evidence suggests that these MTHFR SNPs may be an important pharmacogenetic determinant of predicting response to and toxicity of methotrexate and 5-fluorouracil-based cancer and anti-inflammatory treatments because of their well-defined and highly relevant biochemical effects on intracellular folate composition and one-carbon transfer reactions.