Assessing the performance of quantity and quality metrics using the QIAGEN Investigator® Quantiplex® pro RGQ kit

Abstract

The Quantiplex® Pro RGQ kit quantifies DNA in a sample, supports the detection of mixtures and assesses the extent of DNA degradation based on relative ratios of amplified autosomal and male markers. Data show no significant difference in the accuracy and sensitivity of quantification between this and the Promega PowerQuant® System, both detecting the lowest amount of DNA tested, 4 pg. Laboratory controlled mixed male:female DNA samples together with mock sexual assault samples were quantified across a range of mixture ratios. Analysis software detected mixed DNA samples across all ratios for both quantification kits. Subsequent STR analysis using the Investigator® 24Plex QS Kit was able to corroborate mixture detection down to 1:25 male:female DNA ratios, past which point mixtures appeared identical to single-source female samples. Analysis software also detected laboratory degraded DNA samples, with data showing a positive trend between the Degradation Index (DI) and length of time of sonication. When used on ancient remains the assay was able to triage samples for further analysis, and STR profiles were concordant with DNA quantification results in all instances. STR analyses of laboratory-controlled sensitivity, mixture, and degradation studies supports the quality metric obtained from quantification. These data support the use of the Quantiplex® Pro RGQ kit for sample screening and quantification in forensic casework and ancient DNA studies.

Keywords: DNA degradation; DNA typing; Forensic science; Quantification; Real-time PCR; Validation studies.