Plott Tempest J, Karim Noreen, Durbin-Johnson Blythe P, Swift Dionne P, Scott Youngquist R, Salemi Michelle, Phinney Brett S, Rocke David M, Davis Michael G, Parker Glendon J, Rice Robert H
Forensic Science Graduate Program, University of California, Davis, CA, USA; Department of Environmental Toxicology, University of California, Davis, CA, USA.
Department of Environmental Toxicology, University of California, Davis, CA, USA.
Forensic Sci Int Genet. 2020 Jul;47:102309. doi: 10.1016/j.fsigen.2020.102309. Epub 2020 May 22.
Recent reports highlight possible improvements in individual identification using proteomic information from human hair evidence. These reports have stimulated investigation of parameters that affect the utility of proteomic information. In addition to variables already studied relating to processing technique and anatomic origin of hair shafts, an important variable is hair ageing. Present work focuses on the effect of age on protein profiling and analysis of genetically variant peptides (GVPs). Hair protein profiles may be affected by developmental and physiological changes with age of the donor, exposure to different environmental conditions and intrinsic processes, including during storage. First, to explore whether general trends were evident in the population at different ages, hair samples were analyzed from groups of different subjects in their 20's, 40's and 60's. No significant differences were seen as a function of age, but consistent differences were evident between European American and African American hair profiles. Second, samples collected from single individuals at different ages were analyzed. Mostly, these showed few protein expression level differences over periods of 10 years or less, but samples from subjects at 44 and 65 year intervals were distinctly different in profile. The results indicate that use of protein profiling for personal identification, if practical, would be limited to decadal time intervals. Moreover, batch effects were clearly evident in samples processed by different staff. To investigate the contribution of storage (at room temperature) in affecting the outcomes, the same proteomic digests were analyzed for GVPs. In samples stored over 10 years, GVPs were reduced in number in parallel with the yield of identified proteins and unique peptides. However, a very different picture emerged with respect to personal identification. Numbers of GVPs sufficed to distinguish individuals despite the age differences of the samples. As a practical matter, three hair samples per person provided nearly the maximal number obtained from 5 or 6 samples. The random match probability (where the log increased in proportion to the number of GVPs) reached as high as 1 in 10. The data indicate that GVP results are dependent on the single nucleotide polymorphism profile of the donor genome, where environmental/processing factors affect only the yield, and thus are consistent despite the ages of the donors and samples and batchwise effects in processing. This conclusion is critical for application to casework where the samples may be in storage for long periods and used to match samples recently collected.
近期报告强调了利用人发证据中的蛋白质组学信息进行个体识别可能取得的进展。这些报告激发了对影响蛋白质组学信息效用的参数的研究。除了已经研究过的与处理技术和毛干解剖学来源相关的变量外，一个重要变量是毛发老化。目前的工作重点是年龄对蛋白质谱分析和基因变异肽（GVPs）分析的影响。毛发蛋白质谱可能会受到供体年龄的发育和生理变化、暴露于不同环境条件以及内在过程（包括储存期间）的影响。首先，为了探究不同年龄人群中是否存在明显的总体趋势，对20多岁、40多岁和60多岁不同受试者组的毛发样本进行了分析。未观察到随年龄变化的显著差异，但欧美人和非裔美国人的毛发谱之间存在一致的差异。其次，对从单个个体在不同年龄采集的样本进行了分析。大多数情况下，在10年或更短时间内这些样本显示出很少的蛋白质表达水平差异，但间隔44年和65年采集的受试者样本在谱图上明显不同。结果表明，如果可行的话，使用蛋白质谱进行个人识别将仅限于以十年为间隔的时间范围。此外，不同工作人员处理的样本中批次效应明显。为了研究储存（室温下）对结果的影响，对相同的蛋白质组学消化产物进行了GVPs分析。在储存超过10年的样本中，GVPs数量随着已鉴定蛋白质和独特肽产量平行减少。然而，在个人识别方面出现了截然不同的情况。尽管样本年龄不同，但GVPs数量足以区分个体。实际上，每人三个毛发样本提供了几乎与5个或6个样本相同的最大数量。随机匹配概率（对数与GVPs数量成比例增加）高达十分之一。数据表明，GVPs结果取决于供体基因组的单核苷酸多态性谱，其中环境/处理因素仅影响产量，因此尽管供体和样本年龄不同以及处理中的批次效应，结果仍然一致。这一结论对于应用于样本可能长期储存并用于与最近采集的样本匹配的实际案件工作至关重要。
