CHEK2 and breast cancer: Mutations in ATM, CHEK2, and PALB2 accounted for the majority of mutations (4%), consistent with other studies showing that these are the most commonly mutated genes other than BRCA1 and BRCA2 that are associated with an increased risk of FBC.9, 10, 14, 26 While the assayed genes differ slightly between previously reported studies, our results showing a 4.3% mutation rate (Fig. 2) in high and moderate risk breast cancer predisposition genes among BRCA-negative FBC women, are also consistent with these reports.