Genetic variation of different Peruvian populations using 23 autosomal STR markers

In the present study the genetic variation of different Peruvian populations was investigated. The samples for this study were obtained from 669 individuals distributed among 11 populations from Peru. All samples were analyzed using 23 autosomal STR markers. The Arlequin v3.5.2.2 software was used to determine the genetic distances (Fst) of the studied populations. Notable population substructure was detected between some populations.     

SMART:自主研发的混合STR图谱分析系统

目的混合STR图谱的分析是法医遗传学领域的一个难题。目前国内大多数法医DNA实验室依靠人工方法分析混合STR图谱,费时费力,且拆分效果也多有主观性,难以满足日益增长的混合STR图谱分析的需求。本文介绍一套自主研发的混合STR图谱分析系统——SMART(STR Mixture Analysis and Resolution Tools),其能够实现对混合STR图谱的自动化分析,包括拆分混合STR图谱和计算似然比。方法SMART使用的STR峰高的概率模型,考虑了影子峰、降解、基因座特异性扩增效率、峰高变异、插入峰、峰丢失等因素。模型通过比较各个基因型集合拟合当前混合STR图谱的似然值大小来推断最有可能的基因型集合,采用了马尔可夫链蒙特卡洛(MCMC)算法进行求解。结果SMART可应用于不同试剂盒和遗传分析仪产生的数据。经使用ABI-3500XL遗传分析仪和Global Filer试剂盒测试,SMART能够实现对2~5人的混合STR图谱的分析,输出包括混合比例、混合图谱质量、各个贡献者单人的STR基因分型、似然比等多项结果。结论SMART作为一款自主研发的混合STR图谱分析系统,其基本涵盖了国外同类分析系统所具有的功能,技术性能指标达到国际先进水平,能够满足一线法医工作者对于混合STR图谱分析的多样化需求,提高混合STR图谱结果的利用率。     

Separation of sperm and epithelial cells based on fluorescence-activated cell sorting

The detection and separation of spermatozoa is crucial in the forensic investigation of alleged sexual assault cases. Differential lysis and microscopy-based techniques are conventional methods for the isolation of spermatozoa, though are time-consuming and frequently fail with samples containing an unfavourable sperm/epithelial cell ratio. Successful separation by means of fluorescence-activated cell sorting (FACS) has previously been reported, yet little efforts have been dedicated towards the further improvement or routine implementation of this technique. With this ongoing research, a methodology is being developed to sort sperm from epithelial cells by combining the Sperm Hy-Liter™ staining kit and FACS. Sorted sperm cells are then subjected to a direct lysis and low volume PCR (LV-PCR) protocol. Preliminary results demonstrate the successful separation of both cell types at a sperm/epithelial cell ratio of up to 1:500. The direct lysis and LV-PCR protocol allows to produce full haploid profiles from single sperm cells and mostly full diploid profiles from 10 spermatozoa. These data suggest that the proposed methods are potentially viable for forensic casework, yet additional testing is required for validation purposes.     

法医学二代测序STR分型准确度与测序深度的关联性评估

目的利用实验数据对法医学二代测序STR分型测序深度与分型结果准确度的关联性进行评估。方法使用商业化基因组DNA制备单一来源和混合的DNA样本,以Thermo Fisher公司的25重早期测试试剂盒进行目的STR片段扩增,每种扩增产物分别使用4种不同的序列标签平行建库,并控制标记每一种序列标签的文库上机量依次占一张Ion 318芯片的1/4、1/8、1/16、1/32。经Ion PGMTM基因测序仪测序,以及Ion Torrent SuiteTM软件进行数据分析;同时对庞敬博等人发表的基于相同试剂盒和测序仪检测的95名中国汉族无关个体的6928条等位基因、影子峰和噪音序列进行测序深度统计分析,寻找测序深度与STR分型准确度的关联性。结果各基因座测序深度随文库上样量减少而呈明显下降趋势。对于单一来源样本,每张芯片上样不超过8个均一化文库可实现全部基因座的完整分型;对于1∶20比例的混合DNA,每张芯片上样不超过4个均一化文库时,未发现微量组分的等位基因丢失。人群数据测序深度统计显示,该体系基因座间存在不均衡性,有必要针对各基因座分别设定分析阈值参数。结论测序深度与法医学STR分型结果的准确性密切相关,各基因座最低测序深度与平均测序深度的比值可作为设定分析阈值的重要参考指标。本研究确定的单张芯片上样数量仅适用于本实验体系,但相关实验设计和方案可供其他实验体系开展类似工作参考。     

“UNUSUAL” TISSUES AND SAMPLE COLLECTION STRATEGIES ON EXHUMED BODIES

The choice of soft or hard tissues to be sampled in case of exhumation of corpses for identification purposes or family relationship testing is based on the degradation conditions of the corpse: the more the corpse is degraded, the less DNA is expected to be retrieved from soft tissue. Therefore, the choice of the "best" tissue samples usually falls on teeth and bones in these “difficult” cases, even though the DNA extraction procedure requires time and effort and it can often result in unexpected, negative results.We here present the results of a daily practice survey that shows that it is possible to obtain good results even on DNA extracted from tissues that appear to be less “appealing” to the examiner by performing “simple” corneal/scleral swabs along with cartilage.While DNA extracted from cartilage has been already described, to our knowledge there is no evidence of publications in the scientific literature dealing with cornea/sclera as a source of DNA in the forensic laboratory.The obtained results demonstrate that it may be advisable to consider other tissues which bear the potential of returning good profile results despite not appearing particularly useful and better control of contamination.     

雪地中尿液的DNA检验

尿液样本因为提取难度较大，很少有作为物证检材进行法医鉴定的案例，国内亦未见报道。现报告对雪地中遗留尿液进行法医 DNA鉴定的检案 1例，希望在此基础上建立一套尿液 DNA检验的较成熟的方法。     

六色荧光标记快速PCR扩增体系的建立及验证

目的建立PCR快速扩增程序和体系,并对其技术指标进行验证。方法采用六色荧光标记技术,对24个常染色体STR基因座、1个Y-STR基因座和Amelogenin、Y-In Del基因座进行复合扩增及毛细管电泳检测,同时考察体系的灵敏度、特异性、同一性、稳定性、混合样本及批量样本测试,并观察各种常见检材及降解、脱落细胞检材的分型情况。结果所建立的体系灵敏度达0.062 5 ng,快速扩增仅耗时65 min就可获得准确分型;种属特异性高;各种纸质血样本和混合、降解、脱落细胞检材的分型正确。结论本研究建立的快速扩增体系可显著提升检验速率,分型准确、稳定,对建立STR数据库、研究群体遗传学和进行法医学鉴定有重要意义。     

39个STR基因座在二联体亲子鉴定突变案例中的应用

目的探讨39个常染色体STR基因座在二联体亲子鉴定突变案例中的应用价值。方法提取全血基因组,采用AGCU Expressmarker 22荧光检测试剂盒进行二联体亲子鉴定,若出现1~2个矛盾基因座,则加做AGCU 21+1 STR荧光检测试剂盒,计算累计父权指数(CPI)值,根据亲子鉴定判断标准判定结果。结果共检测502例二联体亲子鉴定案例,其中排除亲权关系17例,485例不排除亲权关系,10例出现单基因座不符合。加做AGCU 21+1后除1例出现一个新的STR基因座不符合,其他均符合遗传规律,且CPI≥10 000。结论 39个STR基因座的联合应用能够有效解决二联体亲子鉴定中的大部分突变案例。     

大麻遗传标记的法医学应用研究进展

大麻是大麻科大麻属一年生雌雄异株的草本植物,其内含有具有强烈成瘾性和麻醉性的四氢大麻酚(THC).大麻价格低廉、获取方便、且受到一些国家和地区合法化的影响,目前已成为滥用最广泛的毒品之一.因此,大麻植株的鉴定对于打击毒品犯罪、维护社会稳定具有重要意义.近年来,基于DNA遗传标记的大麻鉴定为案件侦破提供了新的技术手段,针...     

用Y-STR单倍型推断男性个体来源的分析

目的 利用17个Y-STR单倍型数据,推断分析浙江绍兴地区男性个体来源,为Y-STR数据库的建设与应用提供依据.方法 采集绍兴地区6县(市)区,104个镇(乡),1240个村的138个姓氏家族的7384份男性个体血样.采用YfilerTM复合扩增试剂盒进行17个Y-STR分型,所得数据进行县(市/区)/镇(乡/街道)/村/姓氏的组合和县(市/区)/镇(乡/街道)/村/姓氏/单倍型组合分布情况统计分析.结果 在7384份男性样本中,获得2 486种县(市/区)/镇(乡/街道)/村/姓氏组合,4957种县(市/区)/镇(乡/街道)/村/姓氏/单倍型组合,3149种Y-STR单倍型.其单倍型出现的次数从1至52次不等,其中仅出现1次的有2 471种(78.47％).对出现频率为17～ 52次的单倍型数据进行姓氏分析,发现平均有71.0％ (42.9％ ～87.5％)的人员来自同一姓氏,且在地域上多数为相邻镇或村的同姓人员.结论 利用Yfiler系统的17个Y-STR基因座单倍型数据,可以推断浙江绍兴地区男性个体的地域或姓氏来源.