For all included study groups, the pooled analysis presented MTHFR 677 polymorphisms as risks for IHD (TT: Risk ratio (RR) = 1.23, p < 0.0001; CT: RR = 1.04, p = 0.0028, and TT plus CT: RR = 1.09, p < 0.0001), with the T allele having an 11% greater risk of developing IHD (RR = 1.11, p < 0.0001). This evidence concerns the gene MTHFR and myocardial ischemia.