With advances in next generation sequencing (NGS) and expression profiling studies, breast cancer is now understood as a collection of highly heterogeneous diseases with distinct clinical and molecular phenotypes (luminal A, luminal B, HER2-enriched and basal), each leading to unique clinical outcomes in terms of patients’ survival, disease progression rate, and treatment responses (Kalimutho et al., 2015). The gene discussed is ERBB2; the disease is breast cancer.