The flavoenzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) regulates the flow of folate (vitamin B9) between the production of nucleotides and the supply of methyl groups during methionine synthesis [49, 50] and has major effects on the distribution of intracellular folate [51]. MTHFR also plays a pivotal role in the pathogenesis of migraine and hyperhomocysteinemia. This evidence concerns the gene MTHFR and hyperhomocysteinemia.