Department of Forensic Molecular Biology, Erasmus MC University Medical Center Rotterdam, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands.
Int J Legal Med. 2011 Mar;125(2):253-63. doi: 10.1007/s00414-010-0545-2. Epub 2011 Jan 11.
Although the identification of human skin cells is of important relevance in many forensic cases, there is currently no reliable method available. Here, we present a highly specific and sensitive messenger RNA (mRNA) approach for skin identification, meeting the key requirements in forensic analyses. We examined 11 candidate genes with skin-specific expression, as ascertained from expression databases and the literature, as well as five candidate reference genes ascertained from previous studies, in skin samples and in other forensically relevant tissues. We identified mRNA transcripts from three genes CDSN, LOR and KRT9, showing strong over-expression in skin samples relative to samples from forensic body fluids, making them suitable markers for skin identification. Out of the candidate reference genes tested, only ACTB showed similarly high expression in skin and body-fluid samples, providing a suitable reference marker for quantitative real-time PCR (qPCR) analysis of skin. Analyses of palmar and thumbprint skin samples indicate that our qPCR approach for the three skin-targeted mRNA markers, as well as the reference mRNA marker ACTB, is highly sensitive, allowing successful detection of minute amounts of skin material including full, half and quarter thumbprints, albeit with decreased success in decreasing print material. Furthermore, thumbprints stored for 6.5 months provided similar results relative to freshly analysed samples implying reasonable time-wise stability of the three skin-targeted mRNAs as well as the ACTB reference mRNA. Our study represents the first attempt towards reliable mRNA-based skin identification in forensic applications with particular relevance for future trace/touched object analyses in forensic case work. Although the approach for skin identification introduced here can be informative when applied on its own, we recommend for increased reliability the integration of (one or more of) the skin-targeted mRNA markers presented here into multiplex assays additionally including mRNA markers targeting alternative cell types expected in forensic samples.
虽然人类皮肤细胞的鉴定在许多法医学案例中具有重要意义，但目前还没有可靠的方法。在这里，我们提出了一种高度特异性和敏感的信使 RNA (mRNA) 方法用于皮肤识别，满足法医分析的关键要求。我们检查了 11 个具有皮肤特异性表达的候选基因，这些基因是从表达数据库和文献中确定的，以及从之前的研究中确定的 5 个候选参考基因，这些基因在皮肤样本和其他法医相关组织中进行了研究。我们从三个基因 CDSN、LOR 和 KRT9 中鉴定出 mRNA 转录本，这些基因在皮肤样本中相对于法医体液样本表现出强烈的过表达，使它们成为皮肤识别的合适标记物。在测试的候选参考基因中，只有 ACTB 在皮肤和体液样本中表现出相似的高表达，为皮肤的定量实时 PCR (qPCR) 分析提供了合适的参考标记物。手掌和指纹皮肤样本的分析表明，我们的 qPCR 方法用于三个皮肤靶向 mRNA 标记物以及参考 mRNA 标记物 ACTB，具有高度敏感性，允许成功检测到包括完整、半和四分之一指纹在内的微量皮肤材料，尽管随着印迹材料的减少，检测成功率有所下降。此外，储存 6.5 个月的指纹与新鲜分析的样本相比提供了相似的结果，这意味着三个皮肤靶向 mRNAs 以及 ACTB 参考 mRNA 的时间稳定性合理。我们的研究代表了在法医应用中进行可靠的基于 mRNA 的皮肤鉴定的首次尝试，特别是对于未来法医工作中痕量/接触物体分析具有特别的意义。虽然这里介绍的皮肤识别方法本身就具有信息性，但我们建议为了提高可靠性，将本文介绍的一个或多个皮肤靶向 mRNA 标记物整合到多重分析中，该分析还包括预期在法医样本中出现的替代细胞类型的 mRNA 标记物。
