CHEK2 and breast carcinoma: By this approach, we identified loss‐of‐function mutations in 6/20 (30%) probands, five of which occurred on BRCA1, CHEK2, and ATM and are esteemed to be risk‐relevant according to our studies (Table 2, Fig. 1), while a novel RAD50 truncating mutation is most likely unrelated to breast cancer.