In our patients, ABL1, ATM, CSF1R, CTNNB1, ERBB2, HRAS, MAP2K4, NF1 and PTEN mutations were found only on Her2-positive ER-negative BC (n = 13) while APC, FBXW7 and MSH2 mutations were solely found on Her2-positive ER-positive samples (n = 9). Here, ESR1 is linked to breast cancer.