Several genes have been shown to be associated with an increased risk of breast cancer, such as damaged DNA repair genes (BRCA1 and BRCA2), tumor protein p53 (TP53), Checkpoint kinase 2 (CHEK2), methylenetetrahydrofolate reductase (MTHFR), fibroblast growth factor receptor 2 (FGFR2) and glutathione S-transferase mu 1 (GSTM1) [4]. Here, GSTM1 is linked to breast cancer.