BRCA1 and breast cancer: Depending on the population studied, carriers of pathogenic variants in BRCA1 or BRCA2 have been identified in 40–85% of OC with a family history of breast cancer (BC) and/or OC (i.e., hereditary breast and ovarian cancer (HBOC) syndrome families) and 10–15% of all epithelial OC [6], regardless of the family history of cancer.