Laboratoire de sciences judiciaires et de médecine légale, 1701 Parthenais, Montréal, Québec, H2K 3S7, Canada.
Forensic Sci Int Genet. 2019 Jul;41:24-31. doi: 10.1016/j.fsigen.2019.03.017. Epub 2019 Mar 21.
Probabilistic genotyping approaches are increasingly used for the interpretation of DNA mixtures. To explore the specificity of one of these systems (STRmix), we conducted an extensive study using 24 complex mixtures: all were known or apparent 4-person mixtures with at least one contributor representing less than 20% of total DNA, and all mixtures had at least one contributor with suboptimal DNA quantity. Those mixtures were either generated in-house or from casework. All the mixtures were compared to 300,000 virtual non-contributors, resulting in a dataset of 7.2 million comparisons. The great majority of the non-contributor comparisons led to a LR lower than 1 for a specificity of 99.1%. The effect of using replicate amplifications to calculate the LR of non-contributors was also assessed as triplicates were used and led to an increased specificity of 99.8%. The very large extent of the analyzed data shows that STRmix has an excellent ability to discriminate non-contributors from complex DNA mixtures.
概率基因分型方法越来越多地用于解释 DNA 混合物。为了探索其中一种系统（STRmix）的特异性，我们使用 24 种复杂混合物进行了广泛的研究：所有混合物都是已知或明显的 4 人混合物，其中至少有一个供体代表总 DNA 的不到 20%，所有混合物都至少有一个供体 DNA 量不理想。这些混合物要么是内部生成的，要么是来自案例工作的。所有混合物都与 30 万个虚拟非供体进行了比较，得到了 720 万次比较的数据。绝大多数非供体比较导致 LR 低于 1，特异性为 99.1%。还评估了使用重复扩增来计算非供体 LR 的效果，因为使用了三倍体，特异性提高到 99.8%。分析数据的范围非常广泛，表明 STRmix 具有从复杂 DNA 混合物中区分非供体的出色能力。
