Fewer differences were detected in the comparisons between the eight PALB2-associated breast cancers with mono-allelic inactivation (two ER−/HER2− and four ER+) and the 683 ER−/HER2− and ER+non-BRCA1/2/PALB2-associated breast cancers (Supplementary Fig. 4c). Here, ESR1 is linked to breast cancer.