Familial BC often related to mutations of non‐BRCA1/2 genes in homologous recombination (HR) pathway (ATM, CHEK2, BARD1, BRIP1, MRE11A, NBN and etc), by DNA damage response pathway (MSH2, MLH1, MSH6, PMS2 and etc) 3, 4 and mismatch recognition pathway (MUTYH, EPCAM and etc).5, 6 Mutations of these genes have been reported to have medium‐to‐high penetrance of hereditary BC.7, 8, 9 The prevalence and spectrum of BC germline mutations in Chinese female patients have not been well investigated. The gene discussed is NBN; the disease is breast cancer.