Recent developments in genetics and molecular biology have classified breast cancer into subtypes based on tumor markers of estrogen (ER), progesterone (PR) and human epidermal growth Factor-2 receptors (Her-2), with the basal-like (ER−, PR−, Her2−) subtype commonly referred to as “triple negative” breast cancer (TNBC) being the most aggressive. The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.