Abstract P2-07-06: Detection of germline mutations in 196 genes in Chinese breast cancer families using targeted capture and next-generation sequencing
Authors: Yang X-C , Wu J , Lu J-S , Liu G-Y , Di G-H , Chen C-M , Hou Y-F , Huang X-Y , Liu Z-B , Yan X , Han Q-X , Shen Z-Z , Shao Z-M , Hu Z 
Published: August 2014

Background: Germline mutations in BRCA1, BRCA2 and other genes predispose to high risks of breast cancer. Genetic testing for germline mutations in BRCA1 and BRCA2 has been widely used in women with severe family history of breast or ovarian cancer in many western countries. However, in China, hereditary breast cancer associated genes and their mutation types remain unclear. So far, there's no recommended guidelines for high-risk populations. Next-Generation Sequencing (NGS) technology has been proved to detect all classes of mutations cost-effectively. Here we describe the first study of germline mutations in 196 genes in Chinese breast cancer families using NGS.

Methods: Breast cancer patients were consecutively enrolled at diagnosis in our hospital between 2011-2012. Inclusion criteria were as follows: Firstly, breast cancer patients are Shanghai natives; secondly, breast cancer patients aged 35 or younger had at least another family member with any type of cancer or those between 35 and 50 years had ≥2 family members with cancer on same side of family or those above 50 years had ≥3 family members with cancer on same side of family. A total of 196 genes were tested and they included two parts. One hundred and twenty-two genes selected were associated with 54 hereditary cancer syndromes and another 74 genes were cancer susceptibility genes proved by researches published on Pubmed up to 2012. Blood samples were collected and genomic DNA were subjected to targeted capture using the Agilent SureSelect DNA kit and sequencing of exons and flanking regions corresponding to 196 genes using the Illumina HiSeq 2000 platform. All classes of genomic alterations were detected. The study was approved by the Scientific and Ethical Committee of the Cancer Hospital of Fudan University. All participants provided informed consent.

Results: Eighty-six breast cancer patients met our inclusion criteria were enrolled in our study. The 86 families totally harbored 456 cancers, mainly including 206(45.2%) breast cancers, 45(9.9%) colorectal carcinomas, 38(8.3%) lung cancers, 36(7.9%) gastric cancers, 28(6.1%) hepatic carcinomas and 17(3.7%) ovarian cancers. A total of 66 germline mutations were detected in 29 genes of 46 probands, including 18 BRCA1 or BRCA2 mutations and one recurrent mutation in each gene, one novel TP53 mutations, one germline mutation in RAD50, PALB2, FANCD2, FANCI, RAD51C, SLX4/FANCP, etc. All of these genes were previously reported in hereditary breast cancer. Of women with germline mutations, the mean age at first primary breast cancer diagnosis was 39.6 y and 10(21.7%) of them had bilateral breast cancer. As for all genomic rearrangements, bioinformatics analysis is in process.

Conclusion: This is the first study to report the spectrum of germline mutations in 196 hereditary cancer associated genes in Chinese familial breast cancer patients regardless of cancer types of family members. It will give us a reference for carrying out genetic counseling in Chinese breast cancer families. At the same time, NGS is an effective method to test many genes simultaneously at low cost.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-07-06.