Triple-negative breast cancer (TNBC) that do not express estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) represent an aggressive subgroup of breast cancer (Brewster et al., 2014) with poor prognosis and limited treatment options in the clinic (Foulkes et al., 2010). The gene discussed is ESR1; the disease is breast carcinoma.