Fig. 1.

Schematic overview of the NGS gene doping detection assay. Genomic DNA with potential traces of gene doping copyDNA in the form of plasmids is isolated from blood. Isolated DNA is fragmented and the fragments are prepared for the sequence procedure by adding sequence adapters. Gene doping copyDNA fragments are hybridized to biotin-labeled xGen lockdown probes targeted to all exon–exon junctions of all known gene doping transcripts. xGen blocking oligos are added during hybridization to prevent nonspecific binding of the xGen lockdown probes to the sequence adapters. After hybridization, the captured fragments are magnetically pulled down with streptavidin beads, PCR-amplified and sequenced on an Illumina MiSeq sequencer