法医遗传学研究新进展

法医遗传学经过近30年发展,已经形成了一套系统的理论和技术体系,相关技术和方法在实际工作中发挥着重要作用。随着实际应用需求的变化和相关基础学科研究的进展,法医遗传学的研究也出现了新变化。本文针对法医遗传学领域的研究进展和发展趋势进行综述,希望能对相关研究和实践提供参考和借鉴。     

Messenger RNA Profiling for Forensic Body Fluid Identification： Research and Applications

Identifying the origin of body fluids left at a crime scene can give a significant insight into crime scene reconstruction by supporting a link betw een sample donors and actual criminal acts. How ev-er, the conventional body fluid identification methods are prone to various limitations, such as time con-sumption, intensive labor, nonparallel manner, varying degrees of sensitivity and limited specificity. Re-cently, the analysis of cell-specific messenger RNA expression （mRNA profiling） has been proposed to supplant conventional methods for body fluid identification. Since 2011, the collaborative exercises have been organized by the European DNA Profiling Group （EDNAP ） in order to evaluate the robustness and reproducibility of mRNA profiling for body fluid identification. The major advantages of mRNA profil-ing, compared to the conventional methods, include higher sensitivity, greater specificity, the ability of detecting several body fluids in one multiplex reaction, and compatibilitywith current DNA extraction and analysis procedure. In the current review ,we provided an overview of the present know ledge and detection methodologies of mRNA profiling for forensic body fluid identification and discussed its possi-ble practical application to forensic casew ork.     

Non-biased lineup instructions do matter – a problem for older witnesses

Abstract

From the limited literature on older witnesses’ identification performance it is known that they are less accurate on lineups compared to younger witnesses. What is less certain is why they show this age deficit and what can be done to aid their performance. Witnesses forgot being given non-biased lineup instructions informing witnesses that the perpetrator may or may not be present. More older witnesses than younger witnesses forgot and witnesses who failed to report remembering these instructions were significantly less accurate on the lineups. In addition, the current study investigated the use of sequential lineup presentation and stringent decision criteria to aid the performance of older witnesses. Sequential presentation was beneficial to both younger and older adults when the lineup was target absent (TA) but was detrimental when the lineup was target present (TP). Stringent decision criteria had no significant beneficial effect. Future directions for aiding older witnesses’ performance are discussed.     

Mighty Morphin’ age progression: how artist,age range,and morphing influences the similarity of forensic age progressions to target individuals

When children go missing, authorities sometimes release age progressed images that are intended to approximate the person's current appearance. The current studies measured the influence of the range between the time when the child went missing and the age portrayed in the age progression on the similarity between the progressions and current images of the targets. Experiment 1 examined whole face images and Experiment 2 examined internal features only. Eight artists were recruited to produce progressions at three age ranges. Also included were averaged (morphed) images made of progressions of the same individual at a given range by different artists. Progressions across shorter ranges produced images more similar than those across longer ranges, and target comparisons yielded higher similarity ratings than foil comparisons. Although there was much variability among artists, the morphed images performed better than the average rating given to all age progressions.     

The effects of target discriminability and criterion placement on accuracy rates in sequential and simultaneous target-present lineups

Abstract

Participants attempted to select previously studied faces from lineups that were administered either sequentially (test faces presented one at a time) or simultaneously (test faces presented altogether). Target discriminability was manipulated by varying the number of facial features that could be used to distinguish the study face from the other test faces (foils) or by varying study face exposure duration. In addition, decision criterion level was manipulated via an instruction manipulation. Results indicated that sequential participants adopted a stricter decision standard under high criterion instructions compared to simultaneous participants. Under liberal criterion setting instructions, the rate at which the target was selected was comparable across lineup procedures. Target discriminability affected target selections to a greater extent in simultaneous compared to sequential lineups. We discuss the applied implications that these findings have regarding correct identifications from lineups.     

Much better than the sequential lineup: a 120-person lineup

Abstract

Large lineups may be more reliable than small ones. However, research has found greatly reduced identifications in 40-person lineups of photos shown sequentially one at a time. The task may be more difficult than necessary. Grouping photos may provide an easier one. Three studies had compared seven-page lineups (42, 84, or 168 members) with lineups of about 20. In the first two studies identification and mistaken choice rates were identical in the large and smaller lineup. Identifications in the 168-person lineup were much less. This study tested a 10-page 120-person lineup, and added a 12-person lineup. No difference was found between the 120- and 24-person lineups, and an interaction in 12-person lineups was found between graduate lab student witnesses and others. False identifications, and the probability that the suspect is innocent when ‘identified’, is much less in 120-person lineups than the 24- or 12-person lineups, or the sequential lineup.     

同卵双生子甄别策略探讨

同卵双生子(MZ)之间存在抗体库差异、甲基化修饰差异和基因突变体差异,甲基化修饰差异的比较可望成为甄别MZ的手段之一,抗体库差异和基因突变体差异比较的方法在甄别MZ方面亦有潜在价值.当前,对MZ的表现遗传以及基因突变等领域的研究还很有限,而抗体库技术的应用方法也有待探讨,因此MZ识别技术的应用前景和发展空间需要进一步摸索与完善.     

论声纹鉴定意见的表述形式

本文针对目前国内外讨论比较热烈的声纹鉴定意见表述问题进行了评述.首先介绍了实践中正在使用的听觉分析法、声谱比对分析法、声学分析法、听觉-声学分析法和说话人自动识别五种鉴定方法,指出了各种方法的优缺点;然后对现存的二元判决、可能性等级、似然比和英国立场声明四种鉴定意见表述形式进行了介绍和评析,通过分析发现,上述四种意见表述形式都存在一定的问题,实践中选择何种形式表述鉴定意见要综合考虑其科学性、逻辑性、现实性和可行性等多种价值选项;最后认为解决该问题的根本方法是各相关领域的专家应加强在鉴定方法上的合作性的基础研究.     

Application of direct PCR in forensic casework

Direct PCR is fast becoming a popular method in forensic science due to the advantages of saving time and money in the lab while increasing the probability of obtaining substantial results has a positive rippling effect. A laboratory is able to reduce the time spent on processing trace DNA samples, which can lead to investigators receiving important information in a timely manner that may not have been possible using standard methods. This study highlights the benefits of direct PCR in forensic casework by analysing trace and touch DNA on a range of substrates and exploring the loss of initial DNA due to extraction.