Besides, peculiar genetic aberrations are associated with specific BC subtypes, as CDH1 mutations in Luminal A tumors, CCND1, FGF3, FGF19, and FGFR1 copy gains in estrogen receptor positive BC, whereas MYC amplification, NF1 mutations and BRCA1/2 pathogenic variants were recurrent in triple negative tumors [16,17,18,19]. The gene discussed is ESR1; the disease is breast cancer.