Abstract：
The development of probabilistic genotyping (PG) systems to quantitatively analyze DNA mixture samples has been transformative in forensic science. TrueAllele® Casework (TA) and STRmix™ (STRmix) are the two most widely used PG systems in the United States. The two systems were challenged with 48 two-, three-, and four-person mock casework samples, for a total of 152 likelihood ratio (LR) comparisons. TA and STRmix converged on the same result (supportive, non-supportive, or inconclusive) for ~91% of contributor-specific comparisons. Where moderate or substantial differences in log(LR) values were observed, 9% affected the conclusion of the reference association to the mixture. The PG systems exhibited high correlations for estimated contributor-specific template quantities (~92%) and log(LR)s produced (>88%). When the log(LR)s for only low-template contributors (<100 pg) were compared, the R2 value dropped to ~68% and the difference became statistically significant. Of the 14 contributor comparisons where the conclusion differed, two were contradictory (supportive vs. non-supportive) and 12 were either inconclusive versus non-supportive or inconclusive versus supportive. The differing results were likely due to dissimilarities in the mixture input file as STRmix uses a lab-defined analytical threshold (AT) and TA models to 10 RFUs for each electropherogram. When 7 of the 14 mixtures were reanalyzed by STRmix using a 10 RFU AT, the log(LR)s for the low-template contributors became more similar to TAs. This study shows that while both systems may produce accurate and calibrated LRs, their results can deviate, especially for low-template, degraded contributors, and the deviation is generally predictable.
摘要：
用于定量分析DNA混合物样品的概率基因分型（PG）系统的开发在法医学中具有革命性。TrueAllele®Casewwork(TA)和STRmix™(STRmix)是美国使用最广泛的两种PG系统。这两个系统受到了48个两个挑战-，三-，和四人模拟案例样本，共152个似然比(LR)比较。TA和STRmix融合在相同的结果上(支持，不支持,或不确定)约91%的特定贡献者比较。当观察到对数(LR)值的中等或实质性差异时，9%影响了混合物的参考关联结论。PG系统对于估计的特定于贡献者的模板数量（〜92％）和产生的对数（LR）（>88％）表现出很高的相关性。当仅比较低模板贡献者(<100pg)的日志(LR)时，R2值降至~68%，差异有统计学意义。在结论不同的14个贡献者比较中，两个是矛盾的(支持与非支持性）和12要么是不确定的，要么是不确定的，要么是不确定的，要么是支持的。不同的结果可能是由于混合物输入文件中的差异,因为STRmix使用实验室定义的分析阈值(AT)和TA模型对每个电泳图的10个RFU。当使用10RFUAT通过STRmix对14种混合物中的7种进行重新分析时，低模板贡献者的日志(LR)变得更类似于TA。这项研究表明，虽然两种系统都可以产生精确和校准的LR，他们的结果可能会偏离，特别是对于低模板，退化的贡献者，偏差通常是可预测的。
