An Evaluation Of The Precision Of QIAGEN Quantiplex HYres Kit As a Screening Tool On Low Level Touch DNA Evidence

Abstract

Objective : The primary aim of DNA quantification in forensic DNA analysis is to determine and optimize the amount of DNA for the downstream profiling analysis. Additionally, it may be used as a parameter for the cut-off of the subsequent profiling, especially for touch DNA samples collected from property crime scenes which often contain low amount of DNA and yield no profiles. The choice of quantification kit should have both high accuracy and precision. This work aims to examine the latter of five selected commonly used real-time quantitative PCR (qPCR) kits, namely, Applied Biosystems Quantifiler® kit, Quantifiler® Y kit, Quantifiler® Duo kit, Promega Plexor® HY system and QIAGEN Quantiplex HYres kit, and to seek for a qPCR system fitted for the purpose of initial screening of touched DNA evidence for profiling. Material and Methods : In this work, we first tested the precision of the five selected qPCR kits using their respective DNA standard and human blood samples as substrates. Subsequently, we compared the capability of Quantiplex in predicting the presence of DNA with that of Quantifiler when applying a cut-off threshold of 0.0049 ng/µL and 0.023 ng/µL, i.e. their respective lowest detection limit, with reference to DNA typing analysis. Results : Our results demonstrated that Quantiplex exhibits a higher precision and consistency than the others, especially at low DNA concentration i.e. 0.016 to 0.023 ng/µL. We also showed that, by using a total of 332 simulated touch DNA samples, Quantiplex is a fairly reliable predictor of the AmpFlSTR® Identifiler® profiling results. Conclusion : Quantiplex can be employed as a cost-effective screening of samples of volume crime cases. [ 268 words ]