Evaluation of PowerPlex® Fusion System on samples from forensic casework

Abstract

A newly-commercialised Short Tandem Repeats (STRs) multiplex amplification kit, the PowerPlex® Fusion System (Promega) was evaluated on forensic casework samples and paternity testing. This kit is a 24-loci multiplex including Combined DNA Index System (CODIS) and European Standard Set (ESS) core loci, plus D2S1338, D19S433, Penta E, Penta D markers, Amelogenin for gender discrimination and DYS391 locus to identify null Y allele at Amelogenin locus.Difficult forensic casework samples included teeth, fingernails, mummified skin, formalin fixed paraffin-embedded (FFPE) tissues, buried scheletal muscle and DNA samples collected from various objects (sunglasses, clock, glass, sex toys). Samples were extracted with the QIAamp DNA Investigator kit (Qiagen) and subjected to 28–32 cycles of PCR amplification. Fragments were analyzed on ABI Prism 3130 Genetic Analyzer with software GeneMapper ID-X v1.2 (Applied Biosystems).On average, more than 13 loci could be reliably typed in all forensic casework samples. Furthermore complete drop-out of loci greater than 250–300bp, including DYS391, was observed in highly degraded samples. However, overall sensitivity of the system in typing difficult samples with low amounts of template DNA and in presence of inhibitors was high. Although further validation studies are required, this STR kit represents a valid tool for the analysis of challenging forensic samples.