It can be classified into four subtypes based on the immunohistochemical expression of the following hormone receptors: human epidermal growth factor receptor (HER2), progesterone receptor (PR), and estrogen receptor (ER) [3] as luminal A, luminal HER2-positive, and triple-negative breast cancer (TNBC) [3]. The gene discussed is ESR1; the disease is triple-negative breast carcinoma.