Successful nuclear DNA profiling of rootless hair shafts: a novel approach
Historically, rootless hair shaft samples submitted to a forensic laboratory for DNA analysis are reserved for mitochondrial DNA (mtDNA) analysis due to the presence of highly degraded as well as insufficient amounts of nuclear DNA. Although mtDNA has been very successful in obtaining results from rootless hair, this system has its limitations, namely, it is a lineage marker that cannot differentiate between maternally related genotypes. Given the high incidence of hairs as forensic evidence, there is a need for the use of a nuclear DNA test system capable of producing reliable results for hair shaft forensic evidence. This study reports the utilization of an enhanced DNA extraction methodology for hairs, in combination with a recently developed novel, nuclear DNA typing assay, InnoTyper® 21, to improve the success rate for obtaining informative results from highly compromised, degraded, and trace forensic samples such as rootless hair shafts. The InnoTyper 21 kit is a small amplicon retrotransposon marker typing system compatible with currently used capillary electrophoresis platforms. This system contains 20 Alu element markers, ranging in size from 60 to 125 bp, making the assay highly sensitive for extremely degraded forensic samples and thus enabling recovery of nuclear DNA profiles from samples that would otherwise require mtDNA sequencing. A subset of samples was also tested with the GlobalFiler kit with less success due to the larger amplicon sizes in comparison with InnoTyper 21. Results were variable but very promising, with approximately 40% of the total number of hairs tested producing interpretable nuclear DNA profiles with InnoTyper 21. These results demonstrate the ability of the utilized methodologies to produce nuclear DNA results with high statistical power from rootless hair shafts.
KeywordsInnoTyper® 21 Rootless hair shafts Nuclear DNA DNA extraction
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or the National Institute of Justice.
Compliance with ethical standards
Hair and buccal swab samples collected with approval by the Western Carolina Institutional Review Board. Approval was received on December 19, 2013 (IRB number 2014-0100). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Conflict of interest
Authors Kelly Grisedale and Mark Wilson have no conflicts of interest to declare. Authors Gina Murphy, Hiromi Brown, and Sudhir Sinha are employed by InnoGenomics Technologies, the company that developed and validated the InnoTyper® 21 and InnoQuant® systems.
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