NCJ Number
248153
Journal
Forensic Science International Genetics Volume: 12 Dated: September 2014 Pages: 144-145
Date Published
September 2014
Length
11 pages
Annotation
This study tested the performance of the Ion PGM and the Ion Torrent HID SNP panel by examining SNP typing concordance with the SNPforID assay, sensitivity, and mixtures.
Abstract
Generally, the sequencing performance of the platform was impressive. The allele balance for heterozygotes was close to 1:1 for almost all SNPs, and the number of reads with nucleotide calls that differed from the SNP genotype call (base call errors) was typically less than five. In combination, this made it possible to identify mixtures of 1:100 with a high degree of certainty if the mixture where the coverage for a given locus was 5,000 read or 25 reads with the second allele. The detection of mixtures with SNPs is possible by analyzing the allele balance; however, it is impossible to deconvolute a mixture unless the precise mixture ratio is known, which is unlikely in real casework samples. The optimal amount of input DNA in the Ion Torrent HID SNP assay was less than 0.5 ng. It is likely that the sensitivity may be improved by further optimization of the PCR or by removing some of the weakly amplified SNPs from the panel. The sensitivity study also showed, however, that the allele balance suffered when the amount of input DNA was lower than 0.5 ng. 1 table, 3 figures, and 25 references