The tests, to find if a patient with breast cancer will benefit from HER2 directed therapy, focus on identifying HER2 protein overexpression or gene amplification [copy number variation (CNV)], by immunohistochemistry (IHC) or in situ hybridization (ISH) respectively, as per ASCO-College of American Pathologists (CAP) guidelines [11]. The gene discussed is ERBB2; the disease is breast cancer.