一种基于DNA甲基化的法医体液组织来源鉴定复合扩增体系有效性验证  

Validation of a Multiplex Amplification System for Tissue Identification of Forensic Body Fluids Based on DNA Methylation

作　　者：李琛扬 丁冬升 邹广发 王科文 丰蕾 郭向前 季安全 LI Chenyang;DING Dongsheng;ZOU Guangfa;WANG Kewen;FENG Lei;GUO Xiangqian;JI Anquan(Institute of Forensic Science,Ministry of Public Security(MPS)&MPSʼKey Laboratory of Forensic Genetics,Beijing 100038,China;School of Basic Medical Sciences,Henan University,Kaifeng 175000,Henan,China;Criminal Technology Detachment of Daqing Public Security Bureau,Daqing 163316,Heilongjiang,China)

机构地区：[1]公安部鉴定中心,法医遗传学公安部重点实验室,北京100038 [2]河南大学基础医学院,河南开封175000 [3]大庆市公安局刑事技术支队,黑龙江大庆163316

出　　处：《刑事技术》2025年第2期154-161,共8页Forensic Science and Technology

基　　金：公安部科技强警基础工作专项(2021JC16);现场物证溯源技术国家工程实验室开放课题(2021NELKFKT02)。

摘　　要：本文对文献报道的由9个CpG位点构成的复合扩增体系进行有效性验证,探究该体系在中国人群中的适用性。选取唾液、精液、血液、阴道分泌液、月经血五种体液共236个样本,使用SNaPshot复合扩增体系检测9个CpG位点的甲基化值,位点判定阈值设为甲基化值大于0.1。使用重亚硫酸氢盐转化后DNA(模板量范围为0.5~10 ng)对该体系进行分析。选取唾液、精液、血液、阴道分泌液四种体液DNA,两两分别按照1∶1、1∶5、1∶10、1∶20的比例混合后进行检测。最后,利用五种体液共计232份样本实验数据集进行模型的构建与测试,其中训练集(n=162)用于构建随机森林模型,测试集(n=70)对体液类型进行预测,检验模型预测效果,同时添加外部数据集(n=40)作为验证集对模型的预测效果进行验证。直接根据特异性峰检出判定,唾液、精液、血液、阴道分泌液和月经血样本鉴定准确率分别为100%、98%、98%、94%和21%。该体系对1~10 ng的重亚硫酸氢盐转化后DNA均可有效检测。在混合样本中,1∶1比例混合的样本均可被正确鉴别;1∶5、1∶10和1∶20混合样本均能检出主要成分,次要成分检出存在较大差异。利用232份样本构建随机森林模型,测试集与验证集中的五种体液来源鉴定准确性均为100%。综上,该复合扩增体系具有良好的法医学应用价值。This paper aims to validate the multiplex amplifi cation system of 9 CpG sites reported in the literature,and explore its applicability in the Chinese population.The SNaPshot multiplex amplification system was validated in terms of accuracy,analysis of the initial amount of converted DNA templates,and detection of mixed samples.A total of 236 samples of fi ve types of body fl uids including saliva,semen,blood,vaginal secretion,and menstrual blood were selected.The SNaPshot multiplex amplifi cation system was used to detect the methylation values of 9 CpG sites.The detection threshold of CpG sites was that the methylation value is greater than 0.1.Analyze the starting amount of transformed DNA templates in this system after converting DNA using sodium bisulfi te(template amount ranging from 0.5 ng to 10 ng).DNA extracted from four body fl uids,including saliva,semen,blood,and vaginal secretion,were mixed in the following ratios:1∶1,1∶5,1∶10,and 1∶20.Finally,the detection data set of 232 samples of the fi ve types of body fl uids was used to optimize the existing body fl uid source determination method.The train set(n=162)was used to construct a random forest model,and the test set(n=70)was used to predict the body fl uid type and evaluated the predictive performance of the model.Furthermore,an external data set(n=40)was added to validate the prediction model.In saliva,semen,blood,vaginal secretion samples,and menstrual blood,the body fl uid type was determined directly based on the specifi c sites of body fl uids,and the accuracy rates of body fl uid identifi cation were 100%,98%,98%,94%respectively.Due to the infl uence of the menstrual cycle,some sites were missing,and the average accuracy of menstrual blood identifi cation was 21%.This system could effectively detect the amount of transformed DNA from 1 ng to 10 ng.Among the mixed sample,both body fl uid sources were correctly identifi ed in all 1∶1 mixed samples.The main components could be detected in the other mixed samples(ratio 1∶5,1∶10 and 1

关 键 词：DNA甲基化 复合扩增体系 SNAPSHOT 体液组织来源鉴定 

分 类 号：DF795.2[医药卫生—法医学]