Hereditary BC is characterized by an inherited susceptibility to breast cancer on the basis of an identified germline mutation in BRCA1 and BRCA2 tumor suppressor genes, involved in double strand DNA break repairs, or in one allele of high penetrance susceptibility genes (as TP53, CDH1, PTEN, ...) or low/moderate-penetrance genes (such as ATM, CHEK2 and others) [6]. Here, ATM is linked to breast cancer.