RB1 and breast cancer: Six patients (3.6%) were found to carry a pathogenic or likely pathogenic (P/LP) variant in one of five known breast cancer susceptibility genes: 1.2% in BRCA1, 0.6% in each of BRCA2, ATM, CHEK2 and PALB. A further seven patients carried deleterious variants in one of five hereditary cancer predisposition genes exclusively investigated for truncating variants, specifically ALK, BUB1B, FANCG, RB1 and XPC (Table 1).