Pathogenic variants (PVs) in BRCA1, BRCA2, PALB2, RAD51C, RAD51D, and BRIP1 cancer susceptibility genes (CSGs) confer an increased ovarian cancer (OC) risk, with BRCA1, BRCA2, PALB2, RAD51C, and RAD51D PVs also conferring an elevated breast cancer (BC) risk. This evidence concerns the gene BRCA1 and breast cancer.