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Characterization of a Modified Amplification Approach for Improved STR Recovery From Severely Degraded Skeletal Elements

NCJ Number
Forensic Science International: Genetics Volume: 6 Issue: 5 Dated: September 2012 Pages: 578-587
Jodi A. Irwin; Rebecca S. Just; Odile M. Loreille; Thomas J. Parsons
Date Published
September 2012
10 pages
The authors previously demonstrated the potential of a modified Promega PowerPlex 16 amplification strategy for the recovery of autosomal STR data from severely degraded skeletal elements; in the current study, they further characterize the results obtained under these modified parameters on a variety of sample types, including pristine control DNA and representative case work specimens.
Degraded skeletal remains generally contain limited quantities of genetic material and thus DNA-based identification efforts often target the mitochondrial DNA (mtDNA) control region due to the relative abundance of intact mtDNA as compared to nuclear DNA. In many missing person cases, however, the discriminatory power of mtDNA is inadequate to permit identification when associated anthropological, odontological, or contextual evidence is also limited, and/or the event involves a large number of individuals. In situations such as these, more aggressive amplification protocols that can permit recovery of STR data are badly needed, as they may represent the last hope for conclusive identification. Not only is the amplification approach evaluated in the current study sensitive to extremely low authentic DNA input quantities (6 pg), but when the method was applied to 31 challenging casework specimens, 9 or more alleles were reproducibly recovered from 69 percent of the samples tested. Moreover, when the authors independently considered bone samples extracted with a protocol that includes complete demineralization of the bone matrix, the percentage of samples yielding nine or more reproducible alleles increased to 95 percent with the modified amplification parameters. Overall, direct comparisons between the modified amplification protocol and the standard amplification protocol demonstrated that allele recovery was significantly greater using the aggressive parameters, with only a minimal associated increase in artifactual data. (Published Abstract)


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