Research has identified mutations in moderate penetrance genes like CHEK2, PALB2, ATM, BIRP1, RAD51C, XRCC2, BARD1 in addition to high penetrance genes such as BRCA1/2, P53, PTEN, STK11, CDH1 attributing to the significant familial risk of breast cancer [7]. The gene discussed is ATM; the disease is breast cancer.