MTHFR and Infertility: A study of 1633 cases and 1735 controls from seven case control studies identified the 1298C allele as a genetic risk factor for infertility, whereas a more comprehensive meta-analyses of 3,850 cases and 4,085 controls from twelve published case–control studies did not observe an association of the 1298C genotype with male infertility, although an association with the MTHFR 677T allele was detected [36], [37].