1
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Puch-Solis R, Pope S, Tully G. Considerations on the application of a mutation model for Y-STR interpretation. Sci Justice 2024; 64:180-192. [PMID: 38431375 DOI: 10.1016/j.scijus.2024.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/08/2024] [Accepted: 01/14/2024] [Indexed: 03/05/2024]
Abstract
If Y-STR profiling is to be more effective in criminal casework, the methods used to evaluate evidential weight require improvement. Many forensic scientists assign an evidential weight by estimating the number of times a Y-STR profile obtained from a questioned sample has been observed in YHRD datasets. More sophisticated models have been suggested but not yet implemented into routine casework, e.g. Andersen & Balding [1]. Mutation is inherent to STR meiosis (or inheritance) and is encountered in practice. We evaluated a mutation model that can be incorporated into a method for assigning evidential weight to Y-STR profiles, an essential part of bringing any method into practice. Since an important part of implementation to casework is communication, the article is written in an accessible format for practitioners as well as statisticians. The mutation component within the MUTEA model by Willems et al. [2] incorporates the potential for multistep mutations and a tendency for alleles to revert towards a central length, reflecting observed mutation data, e.g. [3]. We have estimated the parameters in this model and in a simplified symmetric version of this model, using sequence data from father/son pairs [4] and deep-rooted pedigrees [5]. Both datasets contain multistep mutations, which may have an effect on models based on simulations [1]. We introduce Beta-Binomial and Beta-Geometric conjugate analyses for estimating rate and step parameters for the mutation models presented here, which require only summations and multiplications. We proved mathematically that the parameters can be estimated independently. We show the importance of reporting the variability of the parameters and not only a point estimate. The parameters can be easily incorporated into statistical models, and updated sequentially as more data becomes available. We recommend fuller publication of data to enable the development and evaluation of a wider range of mutation models.
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Affiliation(s)
- Roberto Puch-Solis
- Leverhulme Research Centre for Forensic Science, University of Dundee, Dundee DD1 4HN, United Kingdom.
| | - Susan Pope
- Principal Forensic Services, 34 Southborough Road, Bromley, Kent BR1 2EB, United Kingdom
| | - Gillian Tully
- King's Forensics, King's College London, Franklin-Wilkins Building, London, SE1 9NH, United Kingdom
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2
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Huffman K, Ballantyne J. Single cell genomics applications in forensic science: Current state and future directions. iScience 2023; 26:107961. [PMID: 37876804 PMCID: PMC10590970 DOI: 10.1016/j.isci.2023.107961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023] Open
Abstract
Standard methods of mixture analysis involve subjecting a dried crime scene sample to a "bulk" DNA extraction method such that the resulting isolate compromises a homogenized DNA mixture from the individual donors. If, however, instead of bulk DNA extraction, a sufficient number of individual cells from the mixed stain are subsampled prior to genetic analysis then it should be possible to recover highly probative single source, non-mixed scDNA profiles from each of the donors. This approach can detect low DNA level minor donors to a mixture that otherwise would not be identified using standard methods and can also resolve rare mixtures comprising first degree relatives and thereby also prevent the false inclusion of non-donor relatives. This literature landscape review and associated commentary reports on the history and increasing interest in current and potential future applications of scDNA in forensic genomics, and critically evaluates opportunities and impediments to further progress.
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Affiliation(s)
- Kaitlin Huffman
- Graduate Program in Chemistry, Department of Chemistry, University of Central Florida, PO Box 162366, Orlando, FL 32816-2366, USA
| | - Jack Ballantyne
- National Center for Forensic Science, PO Box 162367, Orlando, FL 32816-2367, USA
- Department of Chemistry, University of Central Florida, PO Box 162366, Orlando, FL 32816-2366, USA
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3
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Yao J, Adnan A, Wang HB. Separation mixed semen of two individuals using magnetic beads coupled ABH blood group antibody. Electrophoresis 2023; 44:1539-1547. [PMID: 37650265 DOI: 10.1002/elps.202300021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 05/22/2023] [Accepted: 06/08/2023] [Indexed: 09/01/2023]
Abstract
In sexual assault cases, one of the most common samples collected is a mixed semen stain, which is often found on the vagina, female underwear, or bed sheets. However, it is usually difficult to identify the perpetrator based on this sample alone. One technique that has been developed to address this issue is magnetic bead-based separation. This method involves using modified magnetic microspheres to capture and enrich specific target cells, in this case, sperm cells. In this study, we utilized magnetic beads coupled with ABH blood group antibody to isolate sperm cells from an individual of a single ABO blood type. Subsequently, polymerase chain reaction amplification and capillary electrophoresis were employed to perform the genotyping the short tandem repeat (STR) loci. This approach allows for the identification of different individuals in a mixed seminal stain sample from two individuals, by first separating sperm cells based on ABH antigen differences and subsequently utilizing autosomal STR typing on the enriched single blood group cells.
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Affiliation(s)
- Jun Yao
- Shanghai Key Lab of Forensic Medicine, Key Lab of Forensic Science, Ministry of Justice, China (Academy of Forensic Science), Shanghai, P. R. China
- School of Forensic Medicine, China Medical University, Shenyang, P. R. China
| | - Atif Adnan
- Department of Forensic Sciences, College of Criminal Justice, Naif Arab University for Security Sciences, Riyadh, Kingdom of Saudi Arabia
| | - Hong-Bo Wang
- Department of Anatomy, Shenyang Medical College, Shenyang, P. R. China
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4
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Taylor D, Abarno D. A lights-out forensic DNA analysis workflow for no-suspect crime. Forensic Sci Int Genet 2023; 66:102907. [PMID: 37379740 DOI: 10.1016/j.fsigen.2023.102907] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/13/2023] [Accepted: 06/15/2023] [Indexed: 06/30/2023]
Abstract
An automated system of DNA profile processing (termed a 'lights-out' workflow) was trialled for no-suspect cases over a three-month period at Forensic Science SA (FSSA). The lights-out workflow utilised automated DNA profile reading using the neural network reading feature in FaSTR™ DNA with no analytical threshold. The profile information from FaSTR™ DNA was then processed in STRmix™ using a top-down analysis and automatically compared to a de-identified South Australian searchable DNA database. Computer scripts were used to generate link reports and upload reports and these were compared to the links and uploads that were obtained for the cases during their standard processing within the laboratory. The results of the lights-out workflow was an increase in both uploads and links compared to the standard workflow, with minimal adventitious links or erroneous uploads. Overall, the proof-of-concept study shows the potential for using automated DNA profile reading and top-down analysis to improve workflow efficiency in a no-suspect workflow.
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Affiliation(s)
- Duncan Taylor
- Forensic Science SA, Adelaide, Australia; Flinders University, Adelaide, Australia.
| | - Damien Abarno
- Forensic Science SA, Adelaide, Australia; Flinders University, Adelaide, Australia
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5
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Kruijver M, Taylor D, Buckleton J. Extending the discrete Laplace method: incorporating multi-copy loci, partial repeats and null alleles. Forensic Sci Int Genet 2023; 65:102876. [PMID: 37209602 DOI: 10.1016/j.fsigen.2023.102876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 04/10/2023] [Accepted: 04/16/2023] [Indexed: 05/22/2023]
Abstract
The discrete Laplace method can be used to estimate the frequency of a Y-chromosomal STR haplotype using a random sample from the population. Two limitations of the method are the assumptions that each profile has exactly one allele at every locus and that this allele has an integer repeat number. We relax these assumptions to allow for multi-copy loci, partial repeats and null alleles. We show how the parameters to the extension of the model can be estimated by numerical optimisation using an off-the-shelf solver. Concordance with the discrete Laplace method is obtained when the data satisfy the more stringent assumptions of the original method. We also investigate the performance of the (extended) discrete Laplace method when used to assign match probabilities for haplotypes. A simulation study shows that as more loci are used, match probabilities are underestimated more severely. This is consistent with the hypothesis that the discrete Laplace method cannot model the matches that arise by being identical by descent (IBD). As the number of loci increases the fraction of matches that are IBD increases. Simulation provides support that the discrete Laplace can model those matches that arise from identity by state (IBS) only.
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Affiliation(s)
- Maarten Kruijver
- Institute of Environmental Science and Research, Auckland, New Zealand.
| | - Duncan Taylor
- Forensic Science SA, Adelaide, Australia; School of Biological Sciences, Flinders University, Adelaide, Australia
| | - John Buckleton
- Institute of Environmental Science and Research, Auckland, New Zealand; Department of Statistics, University of Auckland, New Zealand
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6
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Huffman K, Hanson E, Ballantyne J. Y-STR mixture deconvolution by single-cell analysis. J Forensic Sci 2023; 68:275-288. [PMID: 36183153 DOI: 10.1111/1556-4029.15150] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/06/2022] [Accepted: 09/13/2022] [Indexed: 12/31/2022]
Abstract
Since Y-STR typing only amplifies male Y chromosomal DNA, it can simplify the interpretation of some DNA mixtures that contain female DNA. However, if there are multiple male contributors, mixed Y-STR DNA profiles will often be obtained. Y-STR mixture analysis cases are particularly challenging though as, currently, there are no validated probabilistic genotyping (PG) software solutions commercially available to aid in their interpretation. One approach to fully deconvoluting these challenging mixtures into their individual donors is to conduct single-cell genotyping by isolating individual cells from a mixture prior to conducting DNA typing. In this work, a physical micromanipulation technique involving a tungsten needle and direct PCR with decreased reaction volume and increased cycle number was applied to equimolar 2- and 3-person buccal cell male DNA mixtures and a mock touch DNA case scenario involving the consecutive firing of a handgun by two males. A consensus DNA profiling approach was then utilized to obtain YFiler™ Plus Y-STR haplotypes. Buccal cells were used to optimize and test the direct single-cell subsampling approach, and 2-3 person male buccal cell mixtures were fully deconvoluted into their individual donor Y-STR haplotypes. Single-cell (or agglomerated cell clump) subsampling from the gun's trigger recovered single-source Y-STR profiles from both individuals who fired the gun, the owner, and the other unrelated male. Only the non-owner's DNA was found in the cells recovered from the handle. In summary, direct single-cell subsampling as described represents a potential simple way to analyze and interpret Y-STR mixtures.
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Affiliation(s)
- Kaitlin Huffman
- Graduate Program in Chemistry, Department of Chemistry, University of Central Florida, Orlando, Florida, USA
| | - Erin Hanson
- Graduate Program in Chemistry, Department of Chemistry, University of Central Florida, Orlando, Florida, USA.,National Center for Forensic Science, Orlando, Florida, USA.,Department of Chemistry, University of Central Florida, Orlando, Florida, USA
| | - Jack Ballantyne
- Graduate Program in Chemistry, Department of Chemistry, University of Central Florida, Orlando, Florida, USA.,National Center for Forensic Science, Orlando, Florida, USA.,Department of Chemistry, University of Central Florida, Orlando, Florida, USA
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7
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Curtis R, Ward D, Taylor D, Henry J. Investigation of X-STR haplotype diversity in the Australian Aboriginal population. AUST J FORENSIC SCI 2022. [DOI: 10.1080/00450618.2022.2048690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Rhianna Curtis
- Division of Biology, Forensic Science SA, Adelaide, South Australia
| | - Denise Ward
- Division of Biology, Forensic Science SA, Adelaide, South Australia
| | - Duncan Taylor
- Division of Biology, Forensic Science SA, Adelaide, South Australia
- College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia
| | - Julianne Henry
- Division of Biology, Forensic Science SA, Adelaide, South Australia
- College of Science and Engineering, Flinders University of South Australia, Adelaide, South Australia
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8
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Andersen MM, Balding DJ. Assessing the Forensic Value of DNA Evidence from Y Chromosomes and Mitogenomes. Genes (Basel) 2021; 12:genes12081209. [PMID: 34440383 PMCID: PMC8391915 DOI: 10.3390/genes12081209] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 11/17/2022] Open
Abstract
Y chromosome and mitochondrial DNA profiles have been used as evidence in courts for decades, yet the problem of evaluating the weight of evidence has not been adequately resolved. Both are lineage markers (inherited from just one parent), which presents different interpretation challenges compared with standard autosomal DNA profiles (inherited from both parents). We review approaches to the evaluation of lineage marker profiles for forensic identification, focussing on the key roles of profile mutation rate and relatedness (extending beyond known relatives). Higher mutation rates imply fewer individuals matching the profile of an alleged contributor, but they will be more closely related. This makes it challenging to evaluate the possibility that one of these matching individuals could be the true source, because relatives may be plausible alternative contributors, and may not be well mixed in the population. These issues reduce the usefulness of profile databases drawn from a broad population: larger populations can have a lower profile relative frequency because of lower relatedness with the alleged contributor. Many evaluation methods do not adequately take account of distant relatedness, but its effects have become more pronounced with the latest generation of high-mutation-rate Y profiles.
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Affiliation(s)
- Mikkel M. Andersen
- Department of Mathematical Sciences, Aalborg University, 9220 Aalborg, Denmark
- Section of Forensic Genetics, Department of Forensic Medicine, University of Copenhagen, 1165 Copenhagen, Denmark
- Correspondence:
| | - David J. Balding
- Melbourne Integrative Genomics, University of Melbourne, Melbourne 3010, Australia;
- Genetics Institute, University College London, London WC1E 6BT, UK
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Rodriguez JJRB, Laude RP, De Ungria MCA. An integrated system for forensic DNA testing of sexual assault cases in the Philippines. Forensic Sci Int Synerg 2021; 3:100133. [PMID: 33554100 PMCID: PMC7848663 DOI: 10.1016/j.fsisyn.2021.100133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/15/2020] [Accepted: 01/04/2021] [Indexed: 11/20/2022]
Abstract
In the Philippines, more than 7000 cases of sexual assault are reported annually. DNA technology is a powerful tool in identifying assailants. However, it is not routinely used in sexual assault investigations due to insufficient government support to cover the high cost of DNA testing and the absence of a national system for sample collection, handling, storage, and DNA testing of biological evidence. In itself, the nature of sexual assault samples containing DNA mixtures presents challenges to laboratory methods and interpretation of results. The sample recovered from the victim may only contain trace amounts of the assailant’s DNA, may have degraded due to prolonged storage in ambient conditions which is warm and humid in the tropics, or contaminated with inhibitors, such as in anal swabs. Hence, a closer evaluation of the processes of evidence collection and DNA testing is needed to increase the likelihood of success in generating conclusive results. In this paper, we propose an integrated system for DNA testing of biological samples collected from sexual assault victims considering the limitations of resources and the prevailing warm climate. Recommendations in this work should provide basis for formulating national guidelines for DNA analysis in aid of criminal investigations. The proposed scheme can be adopted by forensic DNA laboratories in the Philippines and in other countries facing similar challenges.
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Affiliation(s)
- Jae Joseph Russell B. Rodriguez
- DNA Analysis Laboratory, Natural Sciences Research Institute, University of the Philippines Diliman, Quezon City, 1101, Philippines
- Genetics and Molecular Biology Division, Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Baños, Laguna, 4031, Philippines
| | - Rita P. Laude
- Genetics and Molecular Biology Division, Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Baños, Laguna, 4031, Philippines
| | - Maria Corazon A. De Ungria
- DNA Analysis Laboratory, Natural Sciences Research Institute, University of the Philippines Diliman, Quezon City, 1101, Philippines
- Corresponding author.
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10
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Cowell RG. Consistent estimation of Y STR haplotype probabilities. Forensic Sci Int Genet 2020; 49:102365. [PMID: 32810675 DOI: 10.1016/j.fsigen.2020.102365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/10/2020] [Accepted: 07/27/2020] [Indexed: 12/09/2022]
Abstract
Many methods have been proposed to estimate Y-STR haplotype probabilities in a population, but no consensus has been achieved. In this paper a consistency principle for statistical models to provide such probabilities is proposed, in which it is required that the probability of a given haplotype profile on n loci cannot exceed that of any sub-haplotype matching on any n - 1 or fewer loci. If this consistency principle is violated by a Y haplotype probability model, then it could render the presentation of such probabilities highly problematic in a courtroom setting. We show, using publicly available datasets and two recently proposed graphical models for estimating probabilities of Y-STR haplotypes for illustration, that such violations can occur, and that the violations can in some instances be quite large. Some implications of this are discussed.
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11
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Roewer L, Andersen MM, Ballantyne J, Butler JM, Caliebe A, Corach D, D'Amato ME, Gusmão L, Hou Y, de Knijff P, Parson W, Prinz M, Schneider PM, Taylor D, Vennemann M, Willuweit S. DNA commission of the International Society of Forensic Genetics (ISFG): Recommendations on the interpretation of Y-STR results in forensic analysis. Forensic Sci Int Genet 2020; 48:102308. [PMID: 32622324 DOI: 10.1016/j.fsigen.2020.102308] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 05/06/2020] [Indexed: 10/24/2022]
Abstract
Forensic genetic laboratories perform a large amount of STR analyses of the Y chromosome, in particular to analyze the male part of complex DNA mixtures. However, the statistical interpretation of evidence retrieved from Y-STR haplotypes is challenging. Due to the uni-parental inheritance mode, Y-STR loci are connected to each other and thus haplotypes show patterns of relationship on the familial and population level. This precludes the treatment of Y-STR loci as independently inherited variables and the application of the product rule. Instead, the dependency structure of Y-STRs needs to be included in the haplotype frequency estimation process affecting also the current paradigm of a random match probability that is in the autosomal case approximated by the population frequency assuming unrelatedness of sampled individuals. Information on the degree of paternal relatedness in the suspect population as well as on the familial network is however needed to interpret Y-chromosomal results in the best possible way. The previous recommendations of the DNA commission of the ISFG on the use of Y-STRs in forensic analysis published more than a decade ago [1] cover the interpretation issue only marginally. The current recommendations address a number of topics (frequency estimators, databases, metapopulations, LR formulation, triage, rapidly mutating Y-STRs) with relevance for the Y-STR statistics and recommend a decision-based procedure, which takes into account legal requirements as well as availability of population data and statistical methods.
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Affiliation(s)
- Lutz Roewer
- Institute of Legal Medicine and Forensic Sciences, Dept. Forensic Genetics, Charité - Universitätsmedizin Berlin, Germany.
| | - Mikkel Meyer Andersen
- Department of Mathematical Sciences, Aalborg University, Aalborg, Denmark; Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jack Ballantyne
- National Center for Forensic Science, University of Central Florida, Orlando, USA
| | - John M Butler
- National Institute of Standards and Technology, Special Programs Office, Gaithersburg, USA
| | - Amke Caliebe
- Institute of Medical Informatics and Statistics, Kiel University, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Daniel Corach
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Immunología, Biotecnología y Genética, Cátedra de Genética Forense y Servicio de Huellas Digitales Genéticas, Buenos Aires, Argentina; National Research Council, CONICET, Buenos Aires, Argentina
| | - Maria Eugenia D'Amato
- University of the Western Cape, Department of Biotechnology, Forensic DNA Lab, Cape Town, South Africa
| | - Leonor Gusmão
- State University of Rio de Janeiro (UERJ), Rio de Janeiro, Brazil; IPATIMUP, Institute of Molecular Pathology and Immunology of the University of Porto, Portugal; Instituto de Investigação e Inovação em Saúde, University of Porto, Portugal
| | - Yiping Hou
- Institute of Forensic Medicine, West China School of Basic Science & Forensic Medicine, Sichuan University, Chengdu, China
| | - Peter de Knijff
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Walther Parson
- Institute of Legal Medicine, Medical University of Innsbruck, Innsbruck, Austria; Forensic Science Program, The Pennsylvania State University, University Park, PA, USA
| | - Mechthild Prinz
- John Jay College of Criminal Justice, Dept. of Sciences, New York, USA
| | - Peter M Schneider
- Institute of Legal Medicine, Medical Faculty, University of Cologne, Cologne, Germany
| | - Duncan Taylor
- Forensic Science South Australia, Adelaide, Australia; Flinders University, Adelaide, Australia
| | | | - Sascha Willuweit
- Institute of Legal Medicine and Forensic Sciences, Dept. Forensic Genetics, Charité - Universitätsmedizin Berlin, Germany
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12
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Andersen MM, Caliebe A, Kirkeby K, Knudsen M, Vihrs N, Curran JM. Estimation of Y haplotype frequencies with lower order dependencies. Forensic Sci Int Genet 2020; 46:102214. [DOI: 10.1016/j.fsigen.2019.102214] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 11/05/2019] [Accepted: 11/29/2019] [Indexed: 12/01/2022]
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13
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Bright JA, Kelly H, Kerr Z, McGovern C, Taylor D, Buckleton JS. The interpretation of forensic DNA profiles: an historical perspective. J R Soc N Z 2019. [DOI: 10.1080/03036758.2019.1692044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Jo-Anne Bright
- Forensic Business Group, Institute of Environmental Science and Research Limited, Auckland, New Zealand
| | - Hannah Kelly
- Forensic Business Group, Institute of Environmental Science and Research Limited, Auckland, New Zealand
| | - Zane Kerr
- Forensic Business Group, Institute of Environmental Science and Research Limited, Auckland, New Zealand
| | - Catherine McGovern
- Forensic Business Group, Institute of Environmental Science and Research Limited, Auckland, New Zealand
| | - Duncan Taylor
- Forensic Biology Group, Forensic Science South Australia, Adelaide, Australia
| | - John S. Buckleton
- Forensic Business Group, Institute of Environmental Science and Research Limited, Auckland, New Zealand
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14
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Roewer L. Y‐chromosome short tandem repeats in forensics—Sexing, profiling, and matching male DNA. ACTA ACUST UNITED AC 2019. [DOI: 10.1002/wfs2.1336] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Lutz Roewer
- Department of Forensic Genetics, Institute of Legal Medicine and Forensic Sciences Corporate Member of Freie Universität Berlin, Humboldt‐Universität zu Berlin and Berlin Institute of Health, Charité‐Universitätsmedizin Berlin 13353 Berlin Germany
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15
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Andersen MM, Curran J, de Zoete J, Taylor D, Buckleton J. Modelling the dependence structure of Y-STR haplotypes using graphical models. Forensic Sci Int Genet 2018; 37:29-36. [DOI: 10.1016/j.fsigen.2018.07.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 06/29/2018] [Accepted: 07/16/2018] [Indexed: 11/30/2022]
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16
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Y-profile evidence: Close paternal relatives and mixtures. Forensic Sci Int Genet 2018; 38:48-53. [PMID: 30340211 DOI: 10.1016/j.fsigen.2018.10.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/19/2018] [Accepted: 10/08/2018] [Indexed: 11/21/2022]
Abstract
We recently introduced a new approach to the evaluation of weight of evidence (WoE) for Y-chromosome profiles. Rather than attempting to calculate match probabilities, which is particularly problematic for modern Y-profiles with high mutation rates, we proposed using simulation to describe the distribution of the number of males in the population with a matching Y-profile, both the unconditional distribution and conditional on a database frequency of the profile. Here we further validate the new approach by showing that our results are robust to assumptions about the allelic ladder and the founder haplotypes, and we extend the approach in two important directions. Firstly, forensic databases are not the only source of background data relevant to the evaluation of Y-profile evidence: in many cases the Y-profiles of one or more relatives of the accused are also available. To date it has been unclear how to use this additional information, but in our simulation-based approach its effect is readily incorporated. We describe this approach and illustrate how the WoE that a man was the source of an observed Y-profile changes when the Y-profiles of some of his male-line relatives are also available. Secondly, we extend our new approach to mixtures of Y-profiles from two or more males. Surprisingly, our simulation-based approach reveals that observing a 2-male mixture that includes an alleged contributor's profile is almost as strong evidence as observing a matching single-contributor evidence sample, and even 3-male and 4-male mixtures are only slightly weaker.
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