Harteveld Joyce, Lindenbergh Alexander, Sijen Titia
Department of Human Biological Traces, Netherlands Forensic Institute, The Hague, The Netherlands.
Sci Justice. 2013 Sep;53(3):261-9. doi: 10.1016/j.scijus.2013.02.001. Epub 2013 Mar 5.
Forensic samples regularly involve mixtures, which are readily recognised in forensic analyses. Combined DNA and mRNA profiling is an upcoming forensic practice to examine donors and cell types from the exact same sample. From DNA profiles individual genotypes may be deconvoluted, but to date no studies have established whether the cell types identified in corresponding RNA profiles can be associated with individual donors. Although RNA expression levels hold many variables from which an association may not be expected, proof of concept is important to forensic experts who may be cross examined about this possible correlation in court settings. Clearly, the gender-specificity of certain body fluids (semen, vaginal mucosa, menstrual secretion) can be instructive. However, when donors of the same gender or gender-neutral cell types are involved, alternatives are needed. Here we analyse basic two-component mixtures (two cell types provided by different donors) composed of six different cell types, and assess whether the heights of DNA and RNA peaks may guide association of donor and cell type. Divergent results were obtained; for some mixtures RNA peak heights followed the DNA results, but for others the major DNA component did not present higher RNA peaks. Also, variation in mixture ratios was observed for RNA profiling replicates and when different donor couples gave the same two body fluids. As sample degradation may affect the two nucleic acids and/or distinct cell types differently (and thus influence donor and cell type association), mixtures were subjected to elevated temperature or UV-light. Variation in DNA and RNA stability was observed both between and within cell types and depended on the method inducing degradation. Taken together, we discourage to associate cell types and donors from peak heights when performing RNA and DNA profiling.
法医样本经常涉及混合物，这在法医分析中很容易识别。DNA和mRNA联合分析是一种新兴的法医实践，用于从同一样本中检测供体和细胞类型。从DNA图谱中可以解卷积出个体基因型，但迄今为止，尚无研究确定在相应RNA图谱中鉴定出的细胞类型是否可以与个体供体相关联。尽管RNA表达水平存在许多变量，可能无法预期从中找到关联，但对于可能在法庭环境中就这种可能的相关性接受交叉询问的法医专家来说，概念验证很重要。显然，某些体液（精液、阴道黏膜、月经分泌物）的性别特异性可能具有指导意义。然而，当涉及相同性别的供体或性别中性的细胞类型时，就需要其他方法。在这里，我们分析了由六种不同细胞类型组成的基本双组分混合物（由不同供体提供的两种细胞类型），并评估DNA和RNA峰的高度是否可以指导供体和细胞类型的关联。我们得到了不同的结果；对于一些混合物，RNA峰高与DNA结果一致，但对于另一些混合物，主要的DNA成分并没有呈现出更高的RNA峰。此外，在RNA分析重复实验中以及当不同的供体夫妇提供相同的两种体液时，观察到了混合比例的变化。由于样本降解可能对两种核酸和/或不同细胞类型产生不同影响（从而影响供体和细胞类型的关联），因此对混合物进行了高温或紫外线处理。在细胞类型之间和内部都观察到了DNA和RNA稳定性的变化，并且这取决于诱导降解的方法。综上所述，我们不鼓励在进行RNA和DNA分析时根据峰高来关联细胞类型和供体。
