Since the identification of BRCA1 (1) and BRCA2 (2) as breast cancer (BC) and ovarian cancer (OC) predisposing genes, which are involved in the homologous recombination (HR) DNA repair pathway (3), no other major high risk gene has been reported to account for the remaining familial cancer cases found to be negative for germline pathogenic variants (PVs) in these genes (4). Here, BRCA1 is linked to breast cancer.