Abstract POSTER-TECH-1101: Characterization of genomic landscapes of BRCA1 and BRCA2 implicated ovarian cancer specimens from a founder french canadian population

Although molecular genetic profiling of ovarian cancers harboring germline BRCA1/BRCA2 mutations suggest that pathways in common with sporadic cases are involved in the pathogenesis of the disease, overall survival differs between BRCA1, BRCA2 and sporadic disease. To further dissect molecular pathways involved, which could account for differences in pathogenesis of the disease, we have investigated genomic landscapes in the BRCA1 and BRCA2 mutated ovarian cancers. Chromosomal anomalies were assessed in 28 specimens with BRCA1 (n=15), BRCA2 (n=12) or BRCA1 and BRCA2 (n=1) mutations using high-density Illumina SNP arrays. The majority (22/28) are serous adenocarcinomas while the remaining samples were either endometroid (2/28) or mixed adenocarcinomas (4/28). The cases harbor BRCA1/BRCA2 mutations from a French Canadian population, which exhibit strong founder effects. Allelic imbalance, copy number differences, intrachromosomal breaks and homozygous deletions were inferred visually using the Genome Viewer module of the BeadStudio software followed by ASCAT analysis. A statistical analysis was used to directly compare genotypes of BRCA1 versus BRCA2 positive samples. TP53 gene mutation status was also assessed. All samples were found to harbor a somatic TP53 mutation comprised of missense (19/28), nonsense (2/28), frame-shift (4/28) and (3/28) splice mutations. The results were compared to independently derived data generated previously from our group, which was largely comprised of sporadic cases (Wojnarowicz et al 2012), and to the genomic data from the Cancer Genome Atlas project (TCGA). The genomic landscapes of BRCA1 and BRCA2 mutated cancers overlap those reported in previous studies. However, there were significant differences in the genomic landscapes involving chromosome 6q between BRCA1 and BRCA2 mutation-positive cancers. This genomic distinction between BRCA1 and BRCA2 ovarian cancer samples may point to a region containing genes important in the etiology or progression of hereditary cancer. Citation Format: Eman AlShehri, Moria Belanger, Suzanna Arcand, Kathleen Klein Oros, Celia Greenwood, Patricia N. Tonin. Characterization of genomic landscapes of BRCA1 and BRCA2 implicated ovarian cancer specimens from a founder french canadian population [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-TECH-1101.