BRCA1 and breast cancer: Hereditary breast and ovarian cancer (HBOC) caused by germline BRCA1/2 pathogenic mutations (gBRCAms) is predicted to be responsible for about 5% of breast cancers as well as the 15–18% of all ovarian cancers, and an additional 5–7% show somatic BRCA1/2 pathogenic mutations (sBRCAms) [8,9].