Evaluation of InnoQuant® HY and InnoTyper® 21 kits in the DNA analysis of rootless hair samples

Abstract

Forensic laboratories frequently receive biological samples from crime scene investigations with limited DNA in terms of quantity and quality. Hair shafts are a common type of evidence constituting an ideal sample for DNA testing. Nevertheless, the majority of these hairs are rootless. In an attempt to facilitate the analyses of such samples, new DNA quantification (InnoQuant® HY) and amplification (InnoTyper® 21) kits were developed, using mobile elements as molecular markers. The main advantage of the InnoTyper® 21 kit is its ability to amplify short DNA fragments (60–125 bp), overcoing the difficulties in the amplification of samples with low DNA quantity and/or quality. Therefore, the aim of the present work is to evaluate the efficiency of these two kits in rootless hair samples.In this study, the InnoQuant® HY kit revealed that nearly 94% of the samples presented moderate to high DNA degradation, allowing the selection of the most suitable amplification protocol to be applied. The InnoTyper® 21 kit revealed that nearly 95% of the samples presented amplification peaks in its genetic profiles (GP). However, 60% of these samples did not present a good enough quality to be reported according to the Best Practice Manuals (BPMs), guidelines and documents published by the DNA Working Group of European Network of Forensic Science Institutes (ENFSI). Moreover, in approximately 23% of the amplified samples, GPs with enough quality to be reported were retrieved, 10% of which exhibiting a complete GP. The use of this kit allowed obtaining results which could not be produced by the kits routinely used at forensic laboratories.These results demonstrated that InnoQuant® HY and InnoTyper® 21 kits are reliable alternatives for the analysis of nuclear DNA in challenging samples such as rootless hair shafts.