Based on the immunohistochemistry (IHC) expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), BCs can be categorized into 4 distinct molecular subtypes as follows: HER2 overexpression, luminal A, luminal B, and triple-negative breast cancer (TNBC) (2). The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.