However, we observed no statistically significant associations between the combined genotypes of MTR A2756G and either MTHFR A1298C or C667T and breast cancer risk, nor could we test the joint effects of MTR with MTRR or cSHMT genes since MTRR and cSHMT genes were not available in the present study. This evidence concerns the gene MTHFR and breast carcinoma.