Validation study and forensic applications of investigator 24plex QS Kit

Abstract The Investigator 24plex QS Kit (Qiagen) is used for multiplex PCR in forensic human identity and paternity testing. The PCR simultaneously amplifies 22 polymorphic STR markers: the Combined DNA Index System (CODIS) core loci, the European Standard Set (ESS) loci, SE33, DYS391 and Amelogenin. The Investigator 24plex QS Kit is specifically designed for rapid and reliable generation of DNA profiles from blood, buccal swabs, and forensic stains. The kit utilizes QIAGEN’s fast-cycling PCR technology, allowing amplification in around 60 min and provides highly robust results with inhibitor-resistant chemistry. The Investigator 24plex QS Kit Primer Mix contains two innovative internal PCR controls (Quality Sensor QS1 and QS2), which are amplified simultaneously with the polymorphic STR markers, to yield helpful information about the efficiency of the PCR and the presence of PCR inhibitors. The Investigator 24plex QS Kit User Guide describes instrument setup and sample preparation of PCR products using the Applied Biosystems 3500 Series Data Collection Software and the GeneMapper ID-X Software, but an internal validation is always needed. In this study, we report the successful analysis of amplicons obtained with Investigator 24plex QS Kit on the 3500 Genetic Analyzer. We performed internal validation studies following the European Network of Forensic Science Institutes (ENFSI) and the European DNA Profiling Group (EDNAP) guidelines, testing several critical areas of kit performance such as sensibility, sensitivity, DNA mixtures and inhibited samples.