According to St Gallen Conference 2013, breast cancer subtypes are classified as; luminal A (ER and PGR-positive, low rate of Ki-67 and HER2-negative), luminal B1, HER2-negative (ER-positive, PGR <10% or negative, high rate of Ki-67), luminal B2 HER2-positive (ER-positive and PGR-negative), HER2-positive non-luminal (ER and PGR-negative) and basal-like (ER, PGR and HER2-negative). The gene discussed is ERBB2; the disease is breast cancer.