The 12 PALB2-associated breast cancers analyzed by WES were found to harbor a number of somatic mutations (median 139.5, range 63–269) comparable to that of 17 BRCA1-associated breast cancers with bi-allelic inactivation from TCGA (median 143, range 54–1223; P > 0.05, Mann–Whitney U test), and higher than that of the 16 BRCA2-associated breast cancers with bi-allelic inactivation from TCGA (median 74.5, range 38–209; P = 0.006, Mann–Whitney U test). This evidence concerns the gene BRCA2 and breast cancer.