BRCA1/2 mutation spectrum in Chinese early-onset breast cancer

Breast cancer is the most commonly diagnosed cancer among women. Although many studies have reported the mutations among breast cancer patients, few studies have focused among Chinese early-onset breast cancer patients. The purpose of this study is to identify and mutation features and their clinical significance of early-onset Chinese breast cancer patients. A total of 54 female patients diagnosed with breast cancer were enrolled in this study, of which 27 were younger than 40 (study group, mean age 32 years, range, 23-40 years) and 27 were older than 40 (control group, mean age 52 years, range, 41-68 years). Tumor FFPE samples were collected for somatic mutation test, while blood samples or normal tissue were used for germline mutation by both PGM and Miseq platform. All codon exons and functional introns for were covered. The clinical significance of mutation types was cross analyzed in several available database. The novel mutations were confirmed by sanger sequencing. In study group, 14.8% (4/27) and 3.7% (1/27) patients had deleterious germline and somatic mutations respectively. While in control group, only 3.7% (1/27) and 7.4% (2/27) had deleterious germline and somatic mutations respectively. germline mutation c.2623C>T and germline mutation c.5852G>A were found to be novel mutation sites and confirmed by sanger sequencing. Our study found two novel mutation sites in early-onset breast cancer, and also showed that early-onset breast cancer patients are more likely to harbor germline mutations with deleterious and uncertain significance.