PALB2 and breast cancer: Rare high risk alleles such as BRCA1 [3, 4], BRCA2 [5, 6], TP53 [7], STK11, PTEN and CDH1 explain approximately 20–30% of the inherited susceptibility, intermediate-risk alleles in genes such as CHEK2, ATM, BRIP1(FANCJ) [8–10] and PALB2 (FANCN) [11–15] explain an additional 5%, while common lower penetrance alleles explain approximately 16% of the breast cancer risk [16–23].