title: Evaluation of the impact of genetic linkage in forensic identity and relationship testing for expanded DNA marker sets.
abstract: Advances in massively parallel sequencing technology have enabled the combination of a much-expanded number of DNA markers (notably STRs and SNPs in one or combined multiplexes), with the aim of increasing the weight of evidence in forensic casework. However, when data from multiple loci on the same chromosome are used, genetic linkage can affect the final likelihood calculation. In order to study the effect of linkage for different sets of markers we developed the biostatistical tool ILIR, (Impact of Linkage on forensic markers for Identity and Relationship tests). The ILIR tool can be used to study the overall impact of genetic linkage for an arbitrary set of markers used in forensic testing. Application of ILIR can be useful during marker selection and design of new marker panels, as well as being highly relevant for existing marker sets as a way to properly evaluate the effects of linkage on a case-by-case basis. ILIR, implemented via the open source platform R, includes variation and genomic position reference data for over 40 STRs and 140 SNPs, combined with the ability to include additional forensic markers of interest. The use of the software is demonstrated with examples from several different established marker sets (such as the expanded CODIS core loci) including a review of the interpretation of linked genetic data.
authors: Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, Linköping, Sweden; Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden. Electronic address: andreas.tillmar@rmv.se.
authors: Andreas O
authors: AO
authors: Tillmar
authors: Forensic Genetics Unit, Institute of Legal Medicine, University of Santiago de Compostela, Santiago de Compostela, Spain.
authors: Chris
authors: C
authors: Phillips
mesh_terms: D008040:Genetic Linkage; D005819:Genetic Markers; D006801:Humans; D018895:Microsatellite Repeats; D015233:Models, Statistical; D020641:Polymorphism, Single Nucleotide
chemical_list: D005819:Genetic Markers
keywords: Biostatistics; CODIS loci; Linkage; Linkage disequilibrium; Random match calculations; Relationship testing; Simulation