Browsing by Subject "degraded samples"
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Item An Initial Comparison of Applied Biosystems Quantifiler Duo and Promega Plexor HY Real-time PCR DNA Quantification Systems(2008-05-01) Cole, Sarah Kathleen; Arthur Eisenberg; John Planz; Joseph WarrenObjective 1: Sensitive Study: This study was designed to determine the quantity of template DNA below which amplification is not expected to yield a DNA profile. Dilution series of male and female stock DNA ranging from 0.003 ng/μl will independently be run with both Quantifiler Duo and Plexor HY. These samples will be run in duplicate per plate, with duplicate plates being run. We want to determine if the published lowest detection thresholds (0.023 ng/μl for Duo; 0.0032 ng/μl for HY) are concordant with the data obtained. Objective 2: Mixture Study: The purpose of this study is to obtain quantification results for mixtures of male and female DNA, which should allow for calculations of autosomal:Y ratios that can be helpful in determining what type of genetic analysis to pursue (autosomal STR, Y-STR, or both). Mixtures of female and male DNA ranging from 1:1 to 1024:1 (female: male) will be run in duplicate per plate, with duplicate plates being run. We want to find out how minor of a contributor the male can be in an excess of female DNA and still be detected. This is especially important in sexual assault cases where the major contributor is usually female or when the offender is a vasectomized male. Objective 3: Concordance Study: The purpose of this study is to compare quantification results from Quantifiler Duo and Plexor HY with those from Quantifiler Human, specifically in cases when samples are degraded. The majority of these samples originate from unidentified human remains. Patterns of overestimation or underestimation of DNA concentration can help determine which system will be most beneficial in these cases. This is where the new amplicons size featured in Quantifiler Duo is important in comparing the values with previous results for Quantifiler Human. Sample choice will be at the discretion of the laboratory technical leader and Unidentified Human Remains section analysts. These samples will be the ones that are known to be degraded and have previously yielded overestimated results from the Quantifiler Human quantification system, resulting in poor STR data.Item Analysis of Low Copy Number DNA Using Profiler Plus at Increased Amplification Cycles and Modifications in Sample Injection Parameters(2003-08-01) Hynds, Jody Lynn; Arthur Eisenberg; John Planz; Joseph WarrenThere are many DNA testing techniques that can be utilized for samples with low quantities of DNA. Mitochondrial DNA testing is designed for successful DNA sequencing of hair shafts, degraded and burned samples. Newly developed SNP (single nucleotide polymorphisms) testing is also designed for the analysis of challenging samples. The increased interest in the analysis of low copy number DNA samples using STR testing is necessitated since the national database CODIS (Combined Data Index System) currently only accepts the DNA profiles analyzed with the 13 core STR loci. CODIS contains DNA profiles of evidence found at crime scenes, convicted offender and missing persons DNA profiles (4). The goal of this project is to develop methodologies to increase the success rate of LCN DNA samples using STR testing. The experimental design for this study involved the amplification of DNA isolated from buccal swabs using the Profiler Plus multiplex kit at two different DNA input quantities: 0/0156ng (15.6pg) and 0.0312ng (31.2pg). Four separate amplifications of these DNA samples were done at: 28, 30, 32 and 34 cycles. The manufacturer’s recommended cycle number for AmpFISTR Profiler Plus is 28 cycles. These samples were analyzed on both the ABI Prism 310 Genetic Analyzer and the ABI Prism 3100 Genetic Analyzer using OCD standard protocols for loading samples. The injection time and voltage were modified for each of the number of PCR cycles. The best combination of cycle number and injection parameters was chosen for the low copy number reproducibility study.