Thus, the subtypes are luminal A (ER+, PR+, HER-2 negative, Ki-67 < 14%); luminal B HER2- (ER+, PR+, HER-2 negative, Ki-67 ≥ 14%); luminal B HER2+ (ER+, PR+, HER-2+, any Ki-67); HER2 enriched (ER-, PR-, HER2+++); and triple negative (TNBC), (ER-, PR-, HER2-) breast cancer [50]. The gene discussed is ESR1; the disease is breast cancer.