The subgroup of women who are at highest risk for ER- and PR-negative breast cancers are women who carry a germline mutation in BRCA1. These women typically develop "triple-negative" breast cancers (TNBCs), which are defined by the absence of ER, PR and Her2 expression and are thought to be caused by genetic instability that results from a germline mutation in BRCA1 [4]. The gene discussed is ESR1; the disease is triple-negative breast carcinoma.