NCJ Number
252004
Date Published
November 2013
Length
58 pages
Annotation
Findings and methodology are presented for a study that assessed the usefulness of SNP microarrays for the identification of an individual in a mixture of several DNA contributors.
Abstract
The study determined that a set of 3,000 single nucleotide polymorphims (SNPs) specifically selected for the identification of an individual in a mixture of several DNA contributors can accurately achieve this objective with complex DNA mixtures of various compositions, including mixtures of up to 10 individuals. In mixtures composed of the DNAs of six individuals, those contributing as little as 5 percent to a complex DNA mixture were robustly identified, even when the starting DNA amount was as little as 5.0 ng and had undergone whole-genome amplification (WGA) prior to SNP analysis. In addition, under these same conditions, individuals were identified with similar statistical power in the presence of common forensic sample type inhibitors. This approach identified each of 10 individuals in a single DNA mixture with high likelihood when the recommended amount of starting DNA was used, as well as distinguish between parent-child pairs; however, the latter required a slight alteration in likelihood ratio calculations. In the absence of a focused forensic SNP array that contains ~3,000 SNPs, the use of standard arrays can be similarly used, thereby increasing statistical power due to the larger amount of available information. Rather than take a customized approach that used Illumina's GoldenGate technology, researchers identified an "off-the-shelf" SNP microarray that enabled them to test proof of principle without the costly development of a customized chip. Illumina's HumanCytoSNP-12 Infinium HD microarray was selected for this research. Implications for policy and practice are discussed, along with implications for further research. 10 figures, 5 tables, and 14 references