Hanson Erin K, Ballantyne Jack
National Center for Forensic Science, Orlando, FL 32816-2367, USA.
Sci Justice. 2013 Mar;53(1):14-22. doi: 10.1016/j.scijus.2012.03.007. Epub 2012 Apr 15.
The inability to definitively determine the tissue source of origin of forensically relevant biological fluids could result in a failure to provide crucial information necessary to the investigation and prosecution of the case. For example, in instances of sexual assault with a foreign object or digital penetration, the identification of vaginal secretions (VS) transferred to such objects or the perpetrators might be critical in establishing the circumstances of the assault. Conventional serological and immunological methods for body fluid identification can confirm the presence of human blood and semen. However, currently none of the routinely used biochemical tests can definitively identify the presence of human saliva or VS. It has been demonstrated that mRNA (or miRNA) profiling of body fluid stains can provide a degree of identification specificity of tissue and body fluids heretofore unattainable by conventional means. Early promising VS candidate RNA biomarkers, however, failed to exhibit the required degree of specificity or sensitivity and thus, at present, it is not possible for the forensic scientist to definitively identify VS using molecular genetics techniques. The aim of this work was to find novel highly specific RNA biomarkers for the identification of VS. Whole transcriptome profiling (RNA-Seq) of vaginal swab samples from different donors resulted in the identification of a number of putative VS-specific mRNA candidates. After detailed evaluation of >200 candidates from the tens of thousands of mRNA species found in VS, six promising candidates were identified. From these, two gene transcripts, namely CYP2B7P1 and MYOZ1, consistently demonstrated high specificity and sensitivity for VS when used in a qualitative capillary electrophoresis-based assay. Importantly these two biomarkers are able to differentiate between VS and other body fluids containing significant numbers of epithelia, particularly saliva and skin. Significantly, CYP2B7P1 is exceedingly specific with no detectable cross reactivity with other forensically relevant body fluids/tissues noted to date. The other four putatively specific biomarkers are expressed at higher levels in VS compared with saliva and will be more suitable for use with a quantitative (i.e. qRT-PCR) assay format.
无法确切确定法医相关生物体液的组织来源可能导致无法提供案件调查和起诉所需的关键信息。例如,在使用异物或手指插入进行性侵犯的案件中,识别转移到此类物体或犯罪者身上的阴道分泌物(VS)对于确定袭击情况可能至关重要。用于体液识别的传统血清学和免疫学方法可以确认人血和精液的存在。然而,目前常规使用的生化测试都无法明确识别出人类唾液或VS的存在。已证明体液污渍的mRNA(或miRNA)谱分析可以提供一定程度的组织和体液识别特异性,这是传统方法迄今无法实现的。然而,早期有前景的VS候选RNA生物标志物未能表现出所需的特异性或敏感性,因此,目前法医科学家无法使用分子遗传学技术明确识别VS。这项工作的目的是找到用于识别VS的新型高特异性RNA生物标志物。对来自不同供体的阴道拭子样本进行全转录组分析(RNA测序),从而识别出一些假定的VS特异性mRNA候选物。在对VS中发现的数以万计的mRNA种类中的200多个候选物进行详细评估后,确定了六个有前景的候选物。其中,两个基因转录本,即CYP2B7P1和MYOZ1,在基于定性毛细管电泳的检测中用于VS时,始终表现出高特异性和敏感性。重要的是,这两种生物标志物能够区分VS与其他含有大量上皮细胞的体液,特别是唾液和皮肤。值得注意的是,CYP2B7P1具有极高的特异性,与迄今记录的其他法医相关体液/组织没有可检测到的交叉反应。与唾液相比,其他四种假定的特异性生物标志物在VS中的表达水平更高,将更适合用于定量(即qRT-PCR)检测形式。