Hereditary breast cancer is an autosomal dominant syndrome caused by germ-line mutations in the human breast cancer genes, BRCA1 and BRCA2. Mutations in either BRCA1 or BRCA2 are the major causes of familial and early-onset breast cancer. The present study investigated a 33-year-old Chinese female patient with breast cancer using targeted next generation sequencing. A novel heterozygous deletion-insertion was also identified in the BRCA1 gene, c.311_312delinsAGGTTTGCA, which causes the formation of a truncated BRCA1 protein of 109 amino acids instead of a wild-type BRCA1 protein of 1,863 amino acids. These results could potentially expand the mutational spectra of BRCA1-associated breast cancer. In addition, these findings may be valuable for the mutation-based screening and genetic diagnosis of breast cancer.