In addition to germline mutations in BRCA1 and BRCA2, which confer a very high lifetime risk of BCOC (39%–65% and 11%–37%, respectively),1–3 a growing list of moderate-risk and lower-risk markers specific to each cancer type have been identified.4–10 These influence cancer development in a larger proportion of the population despite small-effect sizes. This evidence concerns the gene BRCA1 and cancer.