DNA repair gene panel mutations in young onset prostate cancer cases in the

18 Background: Prostate cancer (PrCa) is the most common solid tumour in men in the Western world. There is substantial evidence that PrCa predisposition is due both to common and rare germline variation. Methods: We screened 167 genes from DNA damage response and repair pathways, within a UK based cohort of young onset cases (diagnosed at < 65 years) and controls. Samples were sequenced using a custom Agilent SureSelectXT bait library and Illumina HiSeq technology and processed using a BWA/GATK 2.8 pipeline. Following sample QC, data were analysed from 1,285 PrCa cases and 1,163 controls. Results: We identified 5,086 single nucleotide variants (SNVs) and 175 indels; 233 unique protein truncating variants (PTVs) with MAF < 0.5% in controls were found in 97 genes of the screening panel. The total proportion of PTV carriers in cases was higher than in controls (14.5% vs. 11.6%, P = 0.036; OR = 1.29, 95% CI 1.01-1.64). This enrichment was greater within the previously reported BROCA gene set of 22 tumour suppressor genes (4.5% vs 2.2%, P = 2.5x10-3; OR = 2.07, 95% CI 1.28-3.34). To identify genes which best to distinguish PrCa cases from controls, we applied the adaptive combination of P values algorithm, ADA, for genes with at least 2 carriers of PTVs. This analysis selected 10 genes, (OR = 3.37, 95% CI 2.05-5.66, PADA= 5.99x10-3); men with PTVs in these were about 3.4-fold more likely to have PrCa (5.8% vs. 1.8%). We subsequently compared aggressive cases (Gleason score ≥ 8, n = 204) with non-aggressive cases (Gleason score ≤ 7, n = 1049) and lethal PrCa cases (cause of death PrCa, n = 183) with indolent cases (Gleason score ≤ 6, n = 563) to evaluate genes associated with poor clinical prognosis. Using ADA, 4 genes were selected for aggressive PrCa ( PADA= 0.006) and 2 of these also for lethal PrCa ( PADA= 0.057). Conclusions: These gene sets provide an 11 gene panel which could be used for clinical testing and will help to facilitate the development of a PrCa specific sequencing panel with both predictive and prognostic potential.