In order to determinate the association between 3 MTHFR gene polymorphisms (C677T, A1298C, and G1793A) and male infertility in Iranian population, Safarinejad and colleagues showed that only C677T polymorphism was associated with an increased risk of idiopathic male infertility, and the 677T allele carriers (TC or TT) had a significantly increased risk of infertility compared with the CC homozygote’s (104). This evidence concerns the gene MTHFR and male infertility.