A mixed DNA profile controversy revisited

Semaan et al. (J Forensic Res, 2020, 11, 453) discuss a mock case “where eight different individuals [P₁ through P₈] could not be excluded in a mixed DNA analysis. Even though … expert DNA mixture analysis software was used.” Two of these are the true donors. The LRs reported are incorrect due to the incorrect entry of propositions into LRmix Studio. This forced the software to account for most of the alleles as drop-in, resulting in LRs 60–70 orders of magnitude larger than expected. P₁, P₂, P₄, P₅, and P₈ can be manually excluded using peak heights. This has relevance when using LRmix which does not use peak heights. We extend the work using the same two reference genotypes who were the true contributors as Semaan et al. (J Forensic Res, 2020, 11, 453). We simulate three two-donor mixtures with peak heights using these two genotypes and analyze using STRmix?. For the simulated 1:1 mixture, one of the non-donors’ LRs supported him being a contributor when no conditioning was used. When considered in combination with any other potential donors (i.e., with conditioning), this non-donor was correctly eliminated. For the 3:1 mixture, all results correctly supported that the non-donors were not contributors. The low-template 4:1 mixture LRs with no conditioning showed support for all eight profiles as donors. However, the results from pair-wise conditioning showed that only the two ground truth donors had LRs supporting that they were contributors to the mixture. We recommend the use of peak heights and conditioning profiles, as this allows better sensitivity and specificity even when the persons share many alleles.     

大连地区汉族人群4个STR基因座的多态性

采用 310型DNA全自动测序仪 ,选用商品化试剂盒AmpFeSTRTM Confiler (PE公司 ) ,复合扩增D16S5 39、CSF1PO、TPOX和TH0 14个STR基因座 ,对大连地区汉族人群进行了基因频率调查 ,现将调查结果报道如下。1　材料和方法6 10份血液来源于大连市中心血站无关个体 ,采用chelex 10 0法[1] [2 ] 提取DNA后采用 310型DNA全自动测序仪 ,按AmpFeSTRTM Confiler试剂盒说明书进行扩增和检测。用GenescanTM 分析软件分析结果并自动比对。2　结果与讨论4个STR基因座的等位基因在大连地区汉族人群中的分布频率见表 1;杂合度 (H)、H期标…     

应用硅珠法提取陈旧骨骼DNA

骨骼相对于人体其他的组织脏器腐败降解慢,是进行高度腐败及白骨化样本DNA检验的唯一检材。但骨骼DNA的提取比较困难,本文运用传统的硅珠法提取骨骼DNA取得了很好的效果。1材料与方法1.1样本1~4年水浸泡、土埋的股骨、肱骨等样本,来自本实验室日常检案检材。1.2方法1.2.1骨骼DNA提取用水洗净骨骼表面,晾干。锯成小块,用锉打磨内外表面。去离子水、乙醇和5%bleach浸泡、晾干,磨成粉末。取骨粉5g;加入0.5mon/L EDTA(pH8.0)溶液,搅拌均匀置于摇床上脱钙12h,去离子水洗两遍,去上清,重复4次[1];沉渣中加入适量裂解液(6mon/L GuSCN,20mo…     

汉族人群五个STR基因座的多态性调查

应用PCR及PAG电泳技术研究了PLA2A、vWA、CYP19、TH和LPL五个基因座的多态性，调查武汉地区汉族无关个体，获得汉族人群的频率分布。五个基因座基因型频率分布与Hardy-Weinberg平衡吻合良好、分别计算基因座的杂合度（H）、个人识别能力（Dp）、非父排除率（PE）和多态性信息总量（PIC）。为法医学应用提供了基础数据。     

中国汉族与日本群体DYFl55S1基因座的遗传多态性

目的探讨Y染色体DYF155S1基因座的遗传多态性及群体间差异。方法 应用MVR-PCR、荧光显谱及DNA序列分析技术,对来自中国群体(北方汉族,64例)和日本群体(43例)男性个体的DYF155S1基因座进行初步分析。结果107例样本共检出了5种重复序列类型,包括新的命名为6型的重复序列,它是在1型的基础上T22A置换所形成,仅存在于日本群体,可作为民族特征性遗传标记。2群体重复序列的排列方式以3134顺序为主,在中国和日本群体中各占73.44％和67.44％,是黄种人的特点。134顺序在中国群体中占第二位,为17.19％,6134排列占日本群体的16.28％。3’端的4型重复序列的平均数目在日本群体为8.8条,明显低于中国群体的12.5条。结论DYF155S1基因座具有非常高的遗传多态性和明显的群体差异。     

山东地区人群9个STR基因座遗传多态性及频率调查

应用AmpFISTRProfilerPlus试剂盒及377型测序仪对山东地区200例无关个体血样进行了9个STR基因座多态性及频率调查,经X2检验,9个基因座基因频率均符合Hardg-Weinberg平衡定律,家系分析均符合孟德尔遗传规律,并应用于案件检验取得良好效果。     

DNA commission of the International Society of Forensic Genetics: Recommendations on the interpretation of mixtures

The DNA commission of the International Society of Forensic Genetics (ISFG) was convened at the 21st congress of the International Society for Forensic Genetics held between 13 and 17 September in the Azores, Portugal. The purpose of the group was to agree on guidelines to encourage best practice that can be universally applied to assist with mixture interpretation. In addition the commission was tasked to provide guidance on low copy number (LCN) reporting. Our discussions have highlighted a significant need for continuing education and research into this area. We have attempted to present a consensus from experts but to be practical we do not claim to have conveyed a clear vision in every respect in this difficult subject. For this reason, we propose to allow a period of time for feedback and reflection by the scientific community. Then the DNA commission will meet again to consider further recommendations.     

牛分枝杆菌esat-6和mpb70-mpb83基因DNA疫苗的免疫效果

用PCR技术和重叠延伸剪接技术获得牛分枝杆菌esat-6基因和mpb70-mpb83融合基因,连接真核表达载体pcDNA3.1(+),构建了重组质粒pCE6和pC70-83-E6。分4组免疫小鼠:pCE6组、pC70-83-E6组、pcDNA3.1(+)和PBS对照组,采用间接ELISA法检测免疫小鼠血清特异性抗体水平,MTT法检测免疫小鼠脾淋巴细胞增殖情况和IFN-γ分泌情况。结果表明,2重组质粒免疫组小鼠的血清抗体水平持续上升,而2对照组始终维持在较低水平,且pC70-83-E6组小鼠的抗体水平高于pCE6组。经PPD刺激后,pCE6组和pC70-83-E6组小鼠的SI值与2对照组均差异显著(P<0.05),2重组质粒免疫组间差异不显著(P>0.05);2重组质粒免疫小鼠脾细胞产生的IFN-γ均显著高于2对照组(P<0.05),且pC70-83-E6组明显高于其他3组(P<0.05)。证实本试验构建的2种牛分枝杆菌DNA疫苗可有效诱导实验动物产生体液免疫和细胞免疫应答。     

单管实时PCR快速检验ABO基因型

目的建立快捷特异的ABO基因分型检测方法。方法根据ABO基因结构特点,设计特异性引物和四色双链探针,采用单管实时PCR方法检测ABO基因,结果与传统免疫学方法相对比。结果该方法可检出常见的3个等位基因,区分常见的6种基因型,全部检测过程可在100min内完成。110例中国人的随机个体定型结果与传统免疫学方法一致。结论实时PCR法进行ABO基因分型,简便快捷,灵敏度高,可以有效地为侦查破案服务。