Improving the Efficiency of DNA Casework Analysis through Simple, Effective, PCR-based Screening Methods

• NCJ Number: 236689
• Author(s): Janice A. Nicklas Ph.D.; Eric Buel Ph.D.
• Date Published: 2009
• Length: 116 pages
• Grant Number(s): 2005-DA-BX-K003
• Agencies: NIJ-Sponsored
• Publication Type: Report (Study/Research); Program/Project Description

Annotation

The major aims of this project were to develop a fast, simple profiling method for sample screening that can select DNA samples that would be most probative, as well as to develop a test for determining a sample's DNA degradation state.

Abstract

Regarding the effort to develop a simple profiling method for selecting DNA samples that would be most probative, researchers succeeded in developing a technique that can discriminate between 95-99 percent of samples from different individuals. Multiplex SNP assays were developed by using a melting FRET technique. In this assay, two probes are present. These are a sensor with a perfect match to one allele (with fluorophore) but with one mismatch to the other allele, as well as an anchor probe (with quencher). As PCR proceeds, fluorescence is quenched; and in the melting phase, fluorescence is gained. Determination of which allele (s) is present depends on the melting temperature at which the fluorescence is regained. Several assays were developed for the six- color Corbett RG6000 and for other four-color real-time instruments. Researchers also added an additional part to the first aim of the project, i.e., the development of a new assay for fast determination of stain donor using high resolution melting (HRM) of STRs. HRM goes beyond classical melt curve analysis by studying the melt in much finer detail using special DNA dyes such as Eva Green. In accomplishing the second aim of the research, i.e., the development of a test for sample DNA degradation state, researchers designed a multiplex PCR with two overlapping Alu amplicons, using the Plexor technology. This report describes how this technology can be used to obtain and quantitative measure of DNA degradation state. 57 figures, 36 references, and a listing of publications and presentations in which the research findings are presented