Up to 50% of women with high-grade serous ovarian carcinoma may harbour a mutation in, or epigenetic silencing of, genes involved in HR repair [14, 79–84] and preclinical data suggested cells deficient in BRCA1/2 and non-BRCA HR repair genes are sensitive to PARPi [6, 7, 10, 85, 86]. The gene discussed is BRCA1; the disease is ovarian serous carcinoma.