Abstract LB-044: Germline mutations in patients with hereditary breast and ovarian cancer establish ERCC2 as a cancer susceptibility gene
Authors: Schrock Evelin , Benet-Pagès Anna , Schubert Steffen , Janavicius Ramūnas , Hackmann Karl , Betcheva-Krajcir Elitza , Mackenroth Luisa , Lehmann Janin , Nissen AM , Altmueller Janine , Thiele Holger , Di Donato Nataliya , Klink Barbara , Kuhlmann Jan D. , Tzschach Andreas , Kast Karin , Wimberger Pauline , Holinski-Feder Elke , Meindl Alfons , Emmert Steffen , Rump Andreas 
Published: August 2015

Abstract
Introduction: Breast and ovarian cancer (BC/OC) predisposition is associated with a number of high- and low-penetrance susceptibility genes. Despite comprehensive testing there is still a large portion of high risk cases without mutation in any of the known susceptibility loci. Therefore novel candidate genes need to be identified. Here we report on the results of testing 94 genes in 717 BC/OC patients from Germany and Lithuania.
Method: Inclusion criteria for the patients in this study were defined by the German Consortium for Breast and Ovarian Cancer. Next generation sequencing (NGS) was performed on an Illumina MiSeq sequencer, with 150 bp paired end sequencing chemistry and an average base coverage of 300 fold. Target enrichment was performed with the Illumina TruSight cancer panel, which includes 94 genes associated with both common (e.g., breast, colorectal) and rare cancers.
Results: In 19.7% of the patients, BRCA1 or BRCA2 variations have been found. These were either clearly pathogenic loss-of-function mutations (43%) or very rare, unclassified missense variations with high probability of a deleterious effect (57%). In 17.9% of the patients we found null-mutations and rare, unclassified missense variants in the acknowledged BC/OC susceptibility genes ATM, CDH1, CHEK2, NBN, PALB2, RAD51C/D and TP53. Analysis of the non-BC/OC genes on the NGS panel identified the “excision repair cross-complementing rodent repair deficiency, complementation group 2” gene (ERCC2 or XPD) as a promising BC/OC predisposition candidate: we found 3 frame-shift mutations and 1 splice-site mutation in four independent BC/OC families. Additionally we found 20 rare, unclassified sequence variations in ERCC2. These variants have a cumulative allele frequency of 2.9% in our BC/OC cohort, which is 14.5-fold overrepresentation compared to the “exome aggregation consortium” (ExAC) cohort (61486 exomes). In all affected families tested so far, the ERCC2 mutations co-segregate with the occurrence of BC and/or OC. Functional assays testing the ERCC2 variants have been initiated. First results show that at least some of the missense variants (e.g. NM_000400.3:p.Val536Met) have lost their DNA repair ability.
Conclusion: Deleterious mutations and probably pathogenic missense variations in ERCC2, which are significantly overrepresented in our BC/OC families and co-segregate with the affected individuals, define ERCC2 clearly as a susceptibility gene for BC/OC predisposition. Functional assays will be continued in order to identify missense variations that diminish the DNA-repair capacity of ERCC2. Affected individuals with excluded mutations in the known BC/OC predisposition genes should be tested for mutations in ERCC2.
Citation Format: Evelin Schrock, Anna Benet-Pagès, Steffen Schubert, Ramūnas Janavicius, Karl Hackmann, Elitza Betcheva-Krajcir, Luisa Mackenroth, Janin Lehmann, AM Nissen, Janine Altmueller, Holger Thiele, Nataliya Di Donato, Barbara Klink, Jan D. Kuhlmann, Andreas Tzschach, Karin Kast, Pauline Wimberger, Elke Holinski-Feder, Alfons Meindl, Steffen Emmert, Andreas Rump. Germline mutations in patients with hereditary breast and ovarian cancer establish ERCC2 as a cancer susceptibility gene. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-044. doi:10.1158/1538-7445.AM2015-LB-044