A mixed DNA profile controversy revisited.

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Serval ID
serval:BIB_22052BC3DBC6
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
A mixed DNA profile controversy revisited.
Journal
Journal of forensic sciences
Author(s)
Kalafut T., Pugh S., Gill P., Abbas S., Semaan M., Mansour I., Curran J., Bright J.A., Hicks T., Wivell R., Buckleton J.
ISSN
1556-4029 (Electronic)
ISSN-L
0022-1198
Publication state
Published
Issued date
01/2022
Peer-reviewed
Oui
Volume
67
Number
1
Pages
128-135
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
Semaan et al. (J Forensic Res, 2020, 11, 453) discuss a mock case "where eight different individuals [P <sub>1</sub> through P <sub>8</sub> ] could not be excluded in a mixed DNA analysis. Even though … expert DNA mixture analysis software was used." Two of these are the true donors. The LRs reported are incorrect due to the incorrect entry of propositions into LRmix Studio. This forced the software to account for most of the alleles as drop-in, resulting in LRs 60-70 orders of magnitude larger than expected. P <sub>1</sub> , P <sub>2</sub> , P <sub>4</sub> , P <sub>5</sub> , and P <sub>8</sub> can be manually excluded using peak heights. This has relevance when using LRmix which does not use peak heights. We extend the work using the same two reference genotypes who were the true contributors as Semaan et al. (J Forensic Res, 2020, 11, 453). We simulate three two-donor mixtures with peak heights using these two genotypes and analyze using STRmix™. For the simulated 1:1 mixture, one of the non-donors' LRs supported him being a contributor when no conditioning was used. When considered in combination with any other potential donors (i.e., with conditioning), this non-donor was correctly eliminated. For the 3:1 mixture, all results correctly supported that the non-donors were not contributors. The low-template 4:1 mixture LRs with no conditioning showed support for all eight profiles as donors. However, the results from pair-wise conditioning showed that only the two ground truth donors had LRs supporting that they were contributors to the mixture. We recommend the use of peak heights and conditioning profiles, as this allows better sensitivity and specificity even when the persons share many alleles.
Keywords
DNA mixtures, LRmix, STRmix™, exhaustive propositions, forensic DNA analysis, probabilistic genotyping, relatives
Pubmed
Web of science
Create date
18/10/2021 7:11
Last modification date
21/07/2022 5:36
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