Its subtype, called triple-negative breast cancer (TNBC), is characterized by the lack of human epidermal growth factor receptor 2 (HER2), estrogen receptors (ER) and progesterone receptors (PR), and accounts for a disproportionately high percentage of breast-cancer fatalities, while constituting only ~ 15% of all invasive cases [2]. The gene discussed is ESR1; the disease is breast carcinoma.