title: Comparative performance of AmpFLSTR® Identifiler® Plus PCR amplification kit and QIAGEN® Investigator® IDplex Plus kit.
abstract: Many forensic STR kits are currently available in the market. The AmpFLSTR® Identifiler® Plus kit, which targets 15 STRs, is commonly used worldwide. The Thai forensic DNA community is built around it in terms of instrument, databases, and interpretation. QIAGEN's IDplex Plus kit targets the same loci, but the PCR cycling time is shorter by about 90min. A direct comparison that assesses forensic parameters and applicability to casework between the two kits has never been carried out. In this study, we performed a direct comparison between the two kits using serial dilutions of two control DNA samples and 60 randomly selected casework samples, including samples taken from improvised explosive devices and terrorist raids. We statistically compared the performance of the two kits in terms of peak height, number of allele detected (allelic drop-out), intra-locus balance, inter-locus balance, inhibitor tolerance, stutter ratio, concordance, and allelic drop-in. The results demonstrate that both kits are statistically similar in performance. IDplex Plus gave higher peak heights in sensitivity test and tolerated inhibitors better, but had slightly worse inter-locus balances and stutter ratios. However, these differences were not practically significant, as seen by the resulting profiles of the casework samples (p=0.601). The performance on low-template samples also was not different. In conclusion, laboratories looking to replace the aging Identifiler® Plus might consider the IDplex Plus as a faster, more robust alternative that fits right into their existing structure without further investment in instrument and DNA database. Having more kits available worldwide by different companies could help bring the technology to different forensic laboratories and the justice system as a whole.
authors.affiliation: Forensic Science Program, Department of Applied Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand.
authors.forename: Dalad
authors.initials: D
authors.lastname: Mattayat
authors.affiliation: Forensic Science Program, Department of Applied Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand.
authors.forename: Thitika
authors.initials: T
authors.lastname: Kitpipit
authors.affiliation: DNA Analysis Center, Scientific Crime Detection Division 10, Royal Thai Police, Hat Yai, Songkhla 90110, Thailand.
authors.forename: Sukanya
authors.initials: S
authors.lastname: Phetpeng
authors.affiliation: Institute of Forensic Medicine, Royal Thai Police, Bangkok 10330, Thailand.
authors.forename: Watee
authors.initials: W
authors.lastname: Asawutmangkul
authors.affiliation: Forensic Science Program, Department of Applied Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand. Electronic address: pthanakiatkrai@gmail.com.
authors.forename: Phuvadol
authors.initials: P
authors.lastname: Thanakiatkrai
mesh_terms: D016172:DNA Fingerprinting / Q000295:instrumentation*; D006801:Humans; D018895:Microsatellite Repeats; D016133:Polymerase Chain Reaction / Q000295:instrumentation*
keywords: AmpFLSTR® Identifiler® Plus; Comparative performance; IDplex Plus; STR typing kit; Short tandem repeat