Low coverage whole genome sequencing of subsequent passages of soft tissue sarcoma patient-derived xenografts

Intent of the experiment: evaluate whether copy number gains and losses occur throughout the processing of passaging, i.e. test the genomic stability of the patient-derived xenograft models. DNA was extracted from frozen xenograft samples of different passages. KAPA DNA Library Preparation Kit was used to prepare DNA libraries, which were sequenced at low coverage on a HiSeq2000 (Illumina) with a V3 flowcell generating 50bp reads. Raw reads were aligned to the human reference genome version hg19 with Burrows-Wheeler Aligner software package and after duplicate removal further analyzed with QDNAseq to exclude known regions with low mapping quality, correct for the genomic wave and to count the reads per bin. Binned data were further segmented with the ASCAT (Allele-Specific Copy number Analysis of Tumours) algorithm.