BRCA1 and breast cancer: Similar to that in many BRCA1- and BRCA2-associated tumors (Maxwell et al., 2017; Riaz et al., 2017), many PALB2-associated breast cancers (i.e., 67%) show loss of the PALB2 wild type allele via acquired pathogenic somatic variants, or via loss-of-heterozygosity (LOH) (Lee et al., 2018; Li et al., 2019).