PALB2 and breast cancer: First, we showed that germline PTVs in ATM, BRCA1, BRCA2, CHEK2, and PALB2 were associated with an increased risk of IC, and were mostly associated with BRCA1, BRCA2, and PALB2. Women with a family history of BC, in combination with deleterious variants in any of these 5 genes, were 4 times more likely to develop IC compared with SDC.