Among the 16 PALB2-associated breast cancers analyzed by WES, the 12 cases with bi-allelic PALB2 inactivation harbored a numerically higher somatic mutation rate (median 139.5, range 63–269) than the four cases without bi-allelic inactivation (median 103, range 59–109; P = 0.09). Here, PALB2 is linked to breast cancer.