Considerations on the application of a mutation model for Y-STR interpretation

IF 1.9 4区医学 Q2 MEDICINE, LEGAL

Science & Justice Pub Date : 2024-01-17 DOI:10.1016/j.scijus.2024.01.001

Roberto Puch-Solis , Susan Pope , Gillian Tully

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引用次数: 0

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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将突变模型应用于 Y-STR 解释的考虑因素

要想使 Y-STR 图谱分析在刑事案件工作中更加有效，就必须改进用于评估证据权重的方法。许多法证科学家通过估算从可疑样本中获得的 Y-STR 图谱在 YHRD 数据集中出现的次数来确定证据权重。有人提出了更复杂的模型，但尚未在常规案件工作中实施，例如 Andersen & Balding [1]。变异是 STR 减数分裂（或遗传）的固有特性，在实际工作中也会遇到。我们对突变模型进行了评估，该模型可纳入为 Y-STR 图谱分配证据权重的方法中，这是将任何方法付诸实践的重要部分。Willems 等人[2]的 MUTEA 模型中的突变部分包含了多步突变的可能性和等位基因向中心长度回归的趋势，反映了观察到的突变数据，如[3]。我们利用父子配对[4]和深根血统[5]的序列数据估算了该模型和该模型简化对称版的参数。这两个数据集都包含多步突变，这可能会对基于模拟的模型产生影响[1]。我们引入了贝塔-二项式分析和贝塔-几何共轭分析来估算本文介绍的突变模型的速率和步长参数，这两种方法只需要求和和乘法。我们用数学方法证明了参数可以独立估算。我们证明了报告参数的可变性而不仅仅是点估计的重要性。这些参数可以很容易地纳入统计模型，并随着更多数据的获得而不断更新。我们建议更全面地公布数据，以便开发和评估更广泛的突变模型。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Science & Justice 医学-病理学

CiteScore

4.20

自引率

15.80%

发文量

审稿时长

81 days

期刊介绍： Science & Justice provides a forum to promote communication and publication of original articles, reviews and correspondence on subjects that spark debates within the Forensic Science Community and the criminal justice sector. The journal provides a medium whereby all aspects of applying science to legal proceedings can be debated and progressed. Science & Justice is published six times a year, and will be of interest primarily to practising forensic scientists and their colleagues in related fields. It is chiefly concerned with the publication of formal scientific papers, in keeping with its international learned status, but will not accept any article describing experimentation on animals which does not meet strict ethical standards. Promote communication and informed debate within the Forensic Science Community and the criminal justice sector. To promote the publication of learned and original research findings from all areas of the forensic sciences and by so doing to advance the profession. To promote the publication of case based material by way of case reviews. To promote the publication of conference proceedings which are of interest to the forensic science community. To provide a medium whereby all aspects of applying science to legal proceedings can be debated and progressed. To appeal to all those with an interest in the forensic sciences.