title: Does zero really mean nothing?-first experiences with the new PowerQuant(TM) system in comparison to established real-time quantification kits.
abstract: DNA quantification is an important step in the molecular genetic analysis of a forensic sample, hopefully providing reliable data on DNA content for a subsequent generation of reproducible STR profiles for identification. For several years, this quantification has usually been done by real-time PCR protocols and meanwhile a variety of assays are commercially available from different companies. The newest one is the PowerQuant(TM) assay by Promega Inc. which is advertised with the promise that a determined DNA concentration of 0 ng/μl in a forensic sample guarantees the impossibility to achieve true STR results, thus allowing to exclude such samples from STR analysis to save time and money. Thus, the goal of this study was to thoroughly verify the quantification step with regard to its suitability as a screening method. We have evaluated the precision and reliability of four different real-time PCR quantification assays by systematically testing DNA dilutions and forensic samples with various DNA contents. Subsequently, each sample was subjected to the Powerplex® ESX 17 fast kit to determine a reliable cutoff level for exclusion of definitely negative samples from STR analysis. An accurate quantification of different cell line DNA dilutions was not possible with any kit. However, at least the PowerQuant(TM) assay provided suitable data analyzing forensic samples, whereas in other systems up to 46 % of negative samples still displayed reliable STR analysis results. All in all, the PowerQuant(TM) assay represents a big step forward, but the evaluation of real-time PCR quantification results has still to be done with great care.
authors.affiliation: Institute of Legal Medicine, University Hospital Essen, Hufelandstr. 55, D-45122, Essen, Germany. micaela.poetsch@uk-essen.de.
authors.forename: Micaela
authors.identifier: http://orcid.org/0000-0003-1364-6487
authors.initials: M
authors.lastname: Poetsch
authors.affiliation: Institute of Legal Medicine, University Hospital Essen, Hufelandstr. 55, D-45122, Essen, Germany.
authors.forename: Helen
authors.initials: H
authors.lastname: Konrad
authors.affiliation: Institute of Legal Medicine, University Hospital Essen, Hufelandstr. 55, D-45122, Essen, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Helmus
authors.affiliation: Institute of Legal Medicine, University Hospital Essen, Hufelandstr. 55, D-45122, Essen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bajanowski
authors.affiliation: ForScix GmbH, Hamburg, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: von Wurmb-Schwark
mesh_terms: D004247:DNA / Q000032:analysis*; D016172:DNA Fingerprinting; D006801:Humans; D018895:Microsatellite Repeats; D060888:Real-Time Polymerase Chain Reaction / Q000295:instrumentation*; D015203:Reproducibility of Results
chemical_list: D004247:DNA
keywords: DNA quantification; Low copy number DNA; Real-time PCR; STR analysis