Graham Eleanor Alison May, Rutty Guy Nathan
Forensic Pathology Unit, University of Leicester, Leicester Royal Infirmary, Leicester, UK.
J Forensic Sci. 2008 Sep;53(5):1074-82. doi: 10.1111/j.1556-4029.2008.00800.x. Epub 2008 Jul 4.
Others have investigated the role that DNA profiling could play as a method for identifying the perpetrator of manual strangulation. These studies have demonstrated that it is possible to collect offender DNA from the skin surface of a victim following physical contact. It is not known whether nonself biological material is normally present on the skin surface due to adventitious transfer occurring during innocent everyday interactions. To test the hypothesis that detectable amounts of nonself DNA are normally present on the skin surface of healthy adult individuals due to the adventitious transfer of DNA occurring during normal day-to-day social interactions, we designed an experiment in three phases. Phase 1 was used to deduce which DNA collection, extraction, and amplification methods were suited to investigating this question. During phase 2, the neck surface of 24 healthy adult volunteers was swabbed. DNA was extracted using the QIAamp DNA mini kit and amplified using the SGM Plus PCR amplification kit, using 28 PCR cycles. The work carried out during phase 3 involved a simulated assault to investigate primary and secondary transfer of DNA during physical contact. It was found that 23% of neck areas swabbed during phase 2 of this investigation showed nondonor alleles in the resulting DNA profile, with 5% of areas showing six or more nondonor alleles. The results of phase 3 showed that primary, secondary, and zero transfer of victim and/or offender DNA could be observed after physical contact and that alleles from an unknown source could still be detected in this more controlled experiment. The data presented in this paper demonstrate that DNA profiles generated after swabbing the skin surface of healthy adults can include components of an unknown source, present due to adventitious transfer. These components, if present in large quantities, have the potential to interfere with DNA profile interpretation of swabs taken for the investigation of physical assault by DNA profiling.
其他人研究了DNA分析作为识别手动勒死犯罪者方法可能发挥的作用。这些研究表明，在身体接触后，有可能从受害者的皮肤表面收集犯罪者的DNA。尚不清楚由于在日常无害互动中发生的偶然转移，非自身生物材料是否通常存在于皮肤表面。为了检验以下假设：由于在正常日常社交互动中发生的DNA偶然转移，健康成年个体的皮肤表面通常存在可检测量的非自身DNA，我们设计了一个分三个阶段的实验。第一阶段用于推断哪种DNA收集、提取和扩增方法适合研究这个问题。在第二阶段，对24名健康成年志愿者的颈部表面进行擦拭取样。使用QIAamp DNA微量提取试剂盒提取DNA，并使用SGM Plus PCR扩增试剂盒进行扩增，共进行28个PCR循环。在第三阶段开展的工作涉及一次模拟攻击，以研究身体接触过程中DNA的初次和二次转移。结果发现，在本次调查的第二阶段擦拭的颈部区域中，有23%在所得DNA图谱中显示出非供体等位基因，其中5%的区域显示出六个或更多非供体等位基因。第三阶段的结果表明，在身体接触后可以观察到受害者和/或犯罪者DNA的初次、二次和零转移，并且在这个更可控的实验中仍然可以检测到来历不明的等位基因。本文提供的数据表明，擦拭健康成年人皮肤表面后生成的DNA图谱可能包括由于偶然转移而存在的来历不明的成分。如果这些成分大量存在，则有可能干扰通过DNA分析对为调查人身攻击而采集的拭子进行的DNA图谱解读。
