In this report, two most representative groups of patients were analyzed, women carriers of the breast cancer gene group (ATM, BRCA1, BRCA2, CHEK2, CDH1, PALB2, PTEN and TP53) and women carriers of mismatch repair (MMR) gene group (MLH1, MSH2, MSH6, PMS2 and EPCAM deletion). The gene discussed is CHEK2; the disease is breast carcinoma.