Falkena Kim, Hoveling Richelle J M, van Weert Angela, Lambrechts Saskia A G, van Leeuwen Ton G, Aalders Maurice C G, van Dam Annemieke
University of Amsterdam, Biomedical Engineering and Physics, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Master of Research Forensic Science, King's College London, Franklin-Wilkins building, 150 Stamford Street, London, UK.
University of Amsterdam, Biomedical Engineering and Physics, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
Forensic Sci Int. 2019 Feb;295:128-136. doi: 10.1016/j.forsciint.2018.12.005. Epub 2018 Dec 14.
During criminal investigations trace DNA samples, including fingermarks, are submitted to laboratories for short tandem repeat (STR) analysis. For most common STR analysis systems a minimum amount of input DNA is required. Upon intake by the forensic laboratory the DNA concentration is estimated using quantitative polymerase chain reaction (qPCR) analysis after which most fingermarks are excluded. To tackle the problem of unnecessary processing in the lab, our study aimed to develop a method, which is able to predict the DNA content in fingermarks directly at the crime scene. Upon excitation with a UV Crime-lite, fingermark residues have autofluorescent properties. We hypothesize that the intensity of the autofluorescence signal of the fingermark content correlates to the DNA concentration in fingermarks. In this study, 164 fingermarks were examined on their autofluorescence intensity when excited at 365nm, the number of nucleated cells, their DNA concentration and the completeness of the STR profiles. No significant correlation was observed between the DNA concentration in fingermarks and the autofluorescence signal, indicating that a high amount of autofluorescence, thus a high amount of biomaterial, does not necessarily guarantee a higher amount of DNA. In addition, the completeness of the STR profiles did not correlate to the autofluorescence signal of fingermarks. A moderate correlation was found between the predicted DNA quantity, based on the number of nucleated cells and the DNA quantity. In summary, the autofluorescence signal of fingermarks cannot directly be used as a guide to select fingermarks for DNA analysis directly at the crime scene. However, predicting the amount of DNA using a sensitive and specific DNA staining method can probably be used to estimate the DNA concentration in touch samples.
在刑事调查中，包括指纹在内的微量DNA样本会被送交实验室进行短串联重复序列（STR）分析。对于大多数常见的STR分析系统，需要有最低量的输入DNA。法医实验室接收样本后，会通过定量聚合酶链反应（qPCR）分析来估计DNA浓度，之后大多数指纹样本会被排除。为了解决实验室中不必要的处理问题，我们的研究旨在开发一种能够在犯罪现场直接预测指纹中DNA含量的方法。在用紫外线犯罪灯激发时，指纹残留物具有自发荧光特性。我们假设指纹内容物的自发荧光信号强度与指纹中的DNA浓度相关。在本研究中，对164个指纹在365nm激发下的自发荧光强度、有核细胞数量、它们的DNA浓度以及STR图谱的完整性进行了检测。未观察到指纹中的DNA浓度与自发荧光信号之间存在显著相关性，这表明大量的自发荧光，即大量的生物材料，并不一定保证有更高量的DNA。此外，STR图谱的完整性与指纹的自发荧光信号也不相关。基于有核细胞数量预测的DNA量与实际DNA量之间发现了中度相关性。总之，指纹的自发荧光信号不能直接作为在犯罪现场直接选择用于DNA分析的指纹的指导。然而，使用灵敏且特异的DNA染色方法预测DNA量可能可用于估计接触样本中的DNA浓度。
