BRCA1 and breast cancer: It is estimated that around 5% of breast cancer cases harbor PVs in established breast cancer susceptibility genes (ATM, BARD1, BRCA1, BRCA2, CHEK2, PALB2, RAD51C, RAD51D, TP53), of which the most prevalent occur in BRCA2, CHEK2 and BRCA1 (Dorling et al., 2021; Hu et al., 2021).