ABSTRACT
Objective To investigate the pathogenic mutations of BRCA1 and BRCA2 in patients with early-onset breast cancer(≤35 years) and explore the relationships between BRCA1/2 mutations and clinical features.Methods Seventy-four patients with early-onset breast cancer were enrolled,who were treated in Hospital 307 between September 2014 and June 2016.High-throughput sequencing was used to test the 49 exon sequences and adjacent sequences of BRCA1 and BRCA2.χ2 test was used to analyze the distribution of BRCA1/2 pathogenic mutations in each group that was set up according to clinical features.Results Fifteen mutations(20.27%) were identified,including 5(6.76%) in BRCA1 and 10(13.51%) in BRCA2.Eleven new pathogenic mutations were discovered,and BRCA1:c.5470_5477delTGCCCAAT was found in one patient.The frequency of BRCA1/2 mutations in the group with a family history of breast cancer or ovarian cancer was higher than in the group without a family history (40.91% vs 11.54%) (χ2=6.534,P=0.011).Conclusion BRCA1/2 pathogenic mutation is significant for early-onset breast cancer,especially for those with a family history of breast or ovarian cancer.The new mutations may be specific to Chinese people.BRCA1:c.5470_5477delTGCCCAAT may be the ancestor mutation among the Chinese.