More than ten genes with breast cancer predisposition have been identified over the past 25 years including the high- penetrant tumor-suppressor genes BRCA1, BRCA2, PTEN, TP53, CDH1, STK11, PALB2 and numerous moderate-penetrant genes like CHEK2, BRIP1 and ATM [4–6]. Here, CHEK2 is linked to breast cancer.