Netherlands Forensic Institute, Division of Biological Traces, Laan van Ypenburg 6, 2497GB, The Hague, The Netherlands.
Netherlands Forensic Institute, Division of Digital and Biometric Traces, The Hague, The Netherlands.
Forensic Sci Int Genet. 2020 Nov;49:102390. doi: 10.1016/j.fsigen.2020.102390. Epub 2020 Sep 7.
This study describes a multi-laboratory validation of DNAxs, a DNA eXpert System for the data management and probabilistic interpretation of DNA profiles [1], and its statistical library DNAStatistX to which, besides the organising laboratory, four laboratories participated. The software was modified to read multiple data formats and the study was performed prior to the release of the software to the forensic community. The first exercise explored all main functionalities of DNAxs with feedback on user-friendliness, installation and general performance. Next, every laboratory performed likelihood ratio (LR) calculations using their own dataset and a dataset provided by the organising laboratory. The organising laboratory performed LR calculations using all datasets. The datasets were generated with different STR typing kits or analysis systems and consisted of samples varying in DNA amounts, mixture ratios, number of contributors and drop-out level. Hypothesis sets had the correct, under- and over-assigned number of contributors and true and false donors as person of interest. When comparing the results between laboratories, the LRs were foremost within one unit on log10 scale. The few LR results that deviated more had differences for the parameters estimated by the optimizer within DNAStatistX. Some of these were indicated by failed iteration results, others by a failed model validation, since unrealistic hypotheses were included. When these results that do not meet the quality criteria were excluded, as is in accordance with interpretation guidelines, none of the analyses in the different laboratories yielded a different statement in the casework report. Nonetheless, changes in software parameters were sought that minimized differences in outcomes, which made the DNAStatistX module more robust. Overall, the software was found intuitive, user-friendly and valid for use in multiple laboratories.
本研究描述了 DNAxs 的多实验室验证，这是一个用于 DNA 图谱数据管理和概率解释的 DNA 专家系统[1]，以及其统计库 DNAStatistX，除了组织实验室外，还有四个实验室参与了该库的建设。该软件经过了修改，可以读取多种数据格式，并且在向法医界发布软件之前进行了研究。第一项练习探索了 DNAxs 的所有主要功能，并对用户友好性、安装和整体性能提供了反馈。接下来，每个实验室都使用自己的数据集和组织实验室提供的数据集进行似然比（LR）计算。组织实验室使用所有数据集进行 LR 计算。这些数据集是使用不同的 STR 分型试剂盒或分析系统生成的，包含 DNA 量、混合比、贡献者数量和缺失水平不同的样本。假设集具有正确、低估和高估的贡献者数量，以及真实和虚假供体作为感兴趣的人。当比较实验室之间的结果时，LR 在对数 10 标度上主要相差一个单位。偏离更多的少数 LR 结果在 DNAStatistX 中的优化器估计的参数上存在差异。其中一些是由于迭代结果失败而指示的，另一些是由于模型验证失败而指示的，因为包含了不切实际的假设。当按照解释指南排除不符合质量标准的这些结果时，不同实验室的分析在案例报告中都没有得出不同的结论。尽管如此，还是寻求了改变软件参数的方法，以最小化结果之间的差异，从而使 DNAStatistX 模块更加稳健。总体而言，该软件被认为直观、用户友好且可在多个实验室中使用。
