The majority of hereditary breast cancer cases result from mutations in BRCA1 and BRCA2 genes, whereas the rest have been linked to less frequent germline mutations in other high penetrance genes such as TP53, STK11, PTEN, CDH1, and PALB2, as well as moderate penetrance genes like ATM and CHEK2 (2). This evidence concerns the gene BRCA1 and breast cancer.