In particular, breast cancer is associated with a few frequently mutated genes together with many rare mutations.2, 15 Among breast cancer subtypes, we confirmed that ER-negative/HER2-negative breast cancers have the highest overall mutation rate.1 This increased mutation frequency is likely due to the intrinsic genomic instability and the high rate of sequence alterations in genes involved in DNA damage response (e.g., BRCA1/2 and TP53), which characterise TNBC.15–17 Moreover, we demonstrated different genetic variations in additional potential candidate cancer genes. The gene discussed is ERBB2; the disease is breast cancer.