Implementation of an NGS-based workflow for BRCA1 and BRCA2 mutation screening

probability to develop familiar breast cancer. To detect BRCA1/2 germline mutations we developed a next-generation sequencing (NGS) routine dia- gnostic workflow, based on the Ion Torrent PGMTM System platform. The Ion AmpliSeqTM BRCA1 and BRCA2 Community Panel was handled with a semi- automatized procedure for multiplex PCR-based library preparation and se- quencing. Data analysis required the implementation of a custom designed bioinformatic pipeline for sequences alignment and for the identification, annotation and filtration of genetic variants. Sanger sequencing was perfor- med to validate candidate mutations, and to re-sequence amplicons having low NGS coverage (<50 reads per amplicon). Negative samples were ana- lyzed using the BRCA HP Kit (Multiplicom) for an effective homopolymeric stretches detection. This workflow together with the potentiality of our bio- informatic pipeline was blindly tested and validated onto a small cohort of patients previously Sanger sequenced, fine-tuning the parameter settings and resulting in a sensitivity of 100% in variant detection. Subsequently, 244 patients were analyzed thus confirming the need of a double check for the homopolymeric stretches with both NGS sequencing and BRCA HP Kit. The NGS-based workflow here proposed was able to decrease the overall