NCJ Number
246418
Journal
Forensic Science International: Genetics Volume: 7 Issue: 5 Dated: September 2013 Pages: 482-487
Date Published
September 2013
Length
6 pages
Annotation
Sequenom launched the first commercial SNP typing kit for human identification, named the iPLEX Sample ID Plus Panel.
Abstract
Sequenom launched the first commercial SNP typing kit for human identification, named the iPLEX Sample ID Plus Panel. The kit amplifies 47 of the 52 SNPs in the SNPforID panel, amelogenin and two Y-chromosome SNPs in one multiplex PCR. The SNPs were analyzed by single base extension SBE and Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry MALDI-TOF MS. In this study, we evaluated the accuracy and sensitivity of the iPLEX Sample ID Plus Panel by comparing the typing results of the iPLEX Sample ID Plus Panel with those obtained with our ISO 17025 accredited SNPforID assay. The average call rate for duplicate typing of any one SNPs in the panel was 90.0% when the mass spectra were analyzed automatically with the MassARRAY TYPER 4.0 genotyping software in real time. Two reproducible inconsistencies were observed error rate: 0.05% at two different SNP loci. In addition, four inconsistencies were observed once. The optimal amount of template DNA in the PCR was >_10 ng. There was a relatively high risk of allele and locus drop-outs when <_1 ng template DNA was used. We developed an R script with a stringent set of forensic analysis parameters based on the peak height and the signal to noise data exported from the TYPER 4.0 software. With the forensic analysis parameters, all inconsistencies were eliminated in reactions with >_10 ng DNA. However, the average call rate decreased to 69.9%. The iPLEX Sample ID Plus Panel was tested on 10 degraded samples from forensic case-work. Two samples could not be typed, presumably because the samples contained PCR and SBE inhibitors. The average call rate was generally lower for degraded DNA samples and the number of inconsistencies higher than for pristine DNA. However, none of the inconsistencies were reproduced and the highest match probability for the degraded samples typed with the panel was 1.7E-9 using the stringent forensic analysis parameters. Although the relatively low sensitivity of the iPLEX Sample ID Plus Panel makes it inappropriate for typing of trace samples from crime scenes, the panel may be interesting for relationship testing and for identification of e.g. samples in biobanks because of the low reagent costs, the limited hands-on time of the iPLEX assay and the automatic analysis of the mass spectra.