HER2 status in breast cancer is used as a prognostic factor, a predictive factor, and a therapy selection factor [3] for the humanized monoclonal antibody trastuzumab (Herceptin®; Genentech), which is an FDA approved drug for use as monotherapy or combined chemotherapy for treatment of breast cancer patients with amplified HER2 status. The gene discussed is ERBB2; the disease is breast cancer.