Women diagnosed with triple negative breast cancer (TNBC: oestrogen, progesterone and human epidermal growth factor receptor 2 [HER2] negative) comprise 10–15% of all breast cancer diagnoses [2] and are more likely to carry a germline BRCA1 pathogenic variant (PV) than hormone positive breast cancers [3–5]. The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.