Detection Of BRCA1/2 Germline Mutations In Chinese Han Woman With Breast Cancer Based On Next-generation Sequencing

Breast cancer is one of the most common malignant tumor for women in the world.It is a serious threat to every woman's health and quality of life.The incidence and mortality of breast cancer in European and American countries has decreased in recent years.Screening for breast cancer in high-risk groups to achieve early detection and then take corresponding prevention and treatment is the mainly way for them.In China,however,with the development of economy,the incidence of breast cancer is progressively increasing,especially in the developed cities such as Beijing,Shanghai and Guangzhou.Breast cancer has become the most common female malignancy in these cities.It has been confirmed that Breast cancer susceptibility genes,BRCA1 and BRCA2 are two most important genes in the development of breast cancer.They are two important tumor-suppressor genes,which involved in DNA repair and maintain the integrity of the genome in the normal circumstances.These functions can regulate the tumor cells negatively.However,when these two genes mutate,cell will grow abnormally for losing its normal adjustment function.In the end,tumor happens.According to studies between BRCA1/2 and breast cancer,carries of germline mutations in these genes are at increased risk of 80%to develop breast cancer by the age of 70,which the onset age will be early.Therefore,females who are at high risk for BRCA1/2 germline mutation should have a gene screening to diagnose and prevent breast cancer so as to reduce the incidence and mortality of breast cancer.Today,the large size of the genes?5592bp and 10257bp,respectively?and lack of hotspot sites make BRCA1/2 gene detection time consuming and costly.Recently progress in next-generation sequencing?NGS?has solved these problems with its high throughput and efficiency.Moreover NGS shows a good performance in detecting a broad spectrum of mutations.Therefore,NGS has a great potential and advantage for the detection of BRCA1/2 mutations.This study is based on the NGS technology to screened entire coding sequences of BRCAl/2 genes so as to study the characteristics of BRCA1/2 mutation for breast cancer patients of Chinese han nationality.Meanwhile,this study is at the aim of finding people who is at high risk of BRCAl/2 gene mutation.This can provide datas for the development of genetic screening guidelines of breast cancer for Chinese female.Methods:595 breast cancer patients in China were divided into two groups according to their clinical information.Coding regions of genes were detected using NGS in a Personal Genome Machine?PGM?.All found pathogenic mutations were confirmed by Sanger sequencing.PolyPhen-2 and SIFT were used to predict the potential of pathopoiesia for variants of uncertain significant?VUS?.Result:The prevalence of BRCA1/2 mutations was 8.07%in Chinese han nationality populations.42 pathogenic mutations were identified in 48 cases,17 cases in BRCA1 and 31 cases in BRCA2 including 19 novel mutations.11 mutations of BRCA1 gene locate in the 10th exon and 10 mutations of BRCA2 gene locate in the 11st exon.One"founder mutation",c.3109C>T,was found in 6 unrelated cases and One recurrent mutation c.9400₉400delG was detected in two cases.9 uncertain significant variants were predicted to be deleterious by PolyPhen-2 and SIFT.There was significant difference between the high risk group and the low risk group for the BRCA1/2 mutation?p<0.05?.In 13 mutational triple-negative breast cancer patients,76.92%carries BRCA1 mutations.There are 6 BRCA2 mutations in 8 family history breast cancer patients who carries mutations.And 77.78%cases carries BRCA2 mutations in 7 mutational early-onset breast cancer patients.All pathogenic mutation were confirmed by Sanger sequencing with an accuracy of 100%.Conclusions:These results suggested that NGS is useful as a rapid,high-throughput and cost-effective screening tool for the analysis of BRCA1/2 mutations.Based on this panel,we found BRCA1/2 germline mutation in China exhibits its own characteristic compared to the Caucasian.Patients who are family history breast cancer?triple-negative breast cancer or early-onset breast cancer should detecte BRCAI/2 genes.