Y-chromosomal kinship estimation for forensic familial searching: YMrCA to the rescue

The Y-chromosome can be used as an identification method to find paternally related males of the perpetrator. When a close Y-haplotype match is identified, the time to their most recent common ancestor (tMRCA) needs to be estimated to reconstruct their genealogy. To date, two mutation models and three online tMRCA calculators exist. But, they do not include individual mutation rates with multi-step changes, while ignoring hidden multiple, back or parallel modifications. To improve tMRCA estimation, we developed a user-friendly calculator, the ‘YMrCA’, including all previously mentioned mutation characteristics. Here, a case using genealogical pairs with confirmed biological kinships visualizes the good estimation performance of the YMrCA compared to the state-of-the-art. Even when genealogical pairs have equal number of mutations, the YMrCA still estimates the correct number of generations due to the inclusion of individual Y-STR mutation rates and the different mutational influencing factors.     

Uses of the NIST 26plex STR assay for human identity testing

Ongoing work at the U.S. National Institute of Standards and Technology has focused on the characterization of 26 autosomal STR loci for human identity testing. These 26 loci are in addition to the existing 13 U.S. core loci and those found in PowerPlex16 and Identifiler commercial STR typing kits. The amplification of the 26 loci has been optimized for degraded extracts in unique miniplex panels and also for reference samples as a single reaction 26plex assay. A study has been performed comparing genotypes obtained with the 26plex primers to those with miniplex panels for allele drop out and concordance. The forensic utility of the 26plex assay was evaluated for situations where additional loci are beneficial. The utility of this large multiplex was also tested in a case involving DNA extracted from degraded bone samples. The 26plex can serve as a low-cost assay (compared to commercially available kits) useful for both sorting comingled remains and providing additional markers for increased statistical support for samples that require “non-trio” family references for human identification.     

广东地区汉族人群 13个 STR基因座的频率调查

目的调查广东地区汉族无关个体的 13个 STR基因座（ D3S1358、 vWA、 FGA、 D8S1179、 D21S11、 D18S51、 D5S818、 D13S317、 D7S820、 D1 6S539、 TH01、 TPOX、 CSF1PO）多态性,研究其在法医学检验中的应用价值。方法用 AmpFlSTR Profiler Plus及 Cofiler二个荧光标记系统对新鲜血样进行 13个基因座的复合扩增,用 ABI 377-96全自动测序仪对扩增产物进行检测,用 GenoTyper软件进行基因分型。结果 13个基因座 PIC >0.5,DP >0.76,家系调查符合孟德尔遗传规律。结论含有 13个 STR基因座的二个荧光标记复合扩增系统可满足法医物证学的个体识别及亲权鉴定的需要。     

Use of DNA profiles for investigation using a simulated national DNA database: Part II. Statistical and ethical considerations on familial searching

Familial searching consists of searching for a full profile left at a crime scene in a National DNA Database (NDNAD). In this paper we are interested in the circumstance where no full match is returned, but a partial match is found between a database member's profile and the crime stain. Because close relatives share more of their DNA than unrelated persons, this partial match may indicate that the crime stain was left by a close relative of the person with whom the partial match was found. This approach has successfully solved important crimes in the UK and the USA. In a previous paper, a model, which takes into account substructure and siblings, was used to simulate a NDNAD [1]. In this paper, we have used this model to test the usefulness of familial searching and offer guidelines for pre-assessment of the cases based on the likelihood ratio. Siblings of “persons” present in the simulated Swiss NDNAD were created. These profiles (N = 10,000) were used as traces and were then compared to the whole database (N = 100,000). The statistical results obtained show that the technique has great potential confirming the findings of previous studies. However, effectiveness of the technique is only one part of the story. Familial searching has juridical and ethical aspects that should not be ignored. In Switzerland for example, there are no specific guidelines to the legality or otherwise of familial searching. This article both presents statistical results, and addresses criminological and civil liberties aspects to take into account risks and benefits of familial searching.     

青岛地区汉族人群13个STR基因座的频率分布及法医学应用

目的　调查青岛地区汉族人群无关个体的 13个STR基因座 (D3S135 8、VWA、FGA、D8S1179、D2 1S11、D18S5 1、D5S818、D13S317、D7S82 0、D16S5 39、TH0 1、TPOX、CSFIPO)的基因频率分布 ,研究其遗传多态性及其在法医学个体识别及亲子鉴定中的应用价值。　方法　用美国ABI - 310型遗传分析仪对ProfilerPlus和Cofiler两个系统的 13个STR基因座的复合扩增产物进行毛细管电泳及四色荧光自动分析检测 ,基因分型软件为GeneScanv3.1和Genotyperv2 .5 .2。　 结果　获得 13个STR基因座在青岛地区汉族人群的基因频率分布数据 ,13个STR基因座的PIC >0 .5 ,DP >0 .71,CCE =0 .999999,TDP值接近 1,TPm =1.2× 10 -14 ,家系调查符合孟德尔遗传规律。　结论　ProfilerPlus和Cofiler两个系统的 13个STR基因座在法医学个体识别及亲子鉴定中具有较高的应用价值。     

Use of subpopulation data in Australian forensic DNA casework

DNA profiling evidence presented in court should be accompanied by a reliable estimate of its evidential weight. In calculating such statistics, allele frequencies from commonly employed autosomal microsatellite loci are required. These allele frequencies should be collected at a level that appropriately represents the genetic diversity that exists in the population. Typically this occurs at broadly defined bio-geographic categories, such as Caucasian or Asian. Datasets are commonly administered at the jurisdictional level. This paper focuses on Australian jurisdictions and assesses whether this current practice is appropriate for Aboriginal Australian and Caucasian populations alike. In keeping with other studies we observe negligible differences between Caucasian populations within Australia when segregated geographically. However segregation of Aboriginal Australian population data along contemporary State and Territory lines appears to mask the diversity that exists within this subpopulation. For this reason datasets collated along more traditional lines may be more appropriate, particularly to distinguish the most genetically differentiated populations residing in the north of the continent.     

CODIS位点在排除亲权中的应用价值

目的 对 CODIS位点 (FGA、 vWA、 CSF1PO、 TH01、 TPOX、 D3S1358、 D5S818、 D7S820、 D8S1179、 D13S317、 D16S539、 D18S51和 D21S11共 13个 STR位点 )在 100例排除亲权的亲子鉴定中的应用价值进行研究。方法 采用 Profiler Plus及 Cofiler荧光标记复合扩增系统,通过 310遗传分析仪对上述二个检测体系扩增产物的基因型进行分析。结果 在排除亲权的母亲－孩子－假设父亲三联体组中,所有观察案例其出现的排除指标数都在 3个以上,平均排除指标数为 6.63个;在假设父亲－孩子二联体组中, 94.0％的观察案例其排除指标数均在 3个以上,平均排除指标数为 5.01个。结论 CODIS位点在排除亲权的二联体和三联体组合亲子鉴定中,都符合鉴定应用要求 ;选择多态性较高的位点与增加排除指标存在直接的联系,以 DP、 H、 PE作为衡量 DNA位点应用价值的指标在具体鉴定实践中是可靠和可行的。     

菲德倍斯试剂检验唾液斑的有效性

目的验证菲德倍斯试剂（Phadebas Forensic tube test）检验唾液（斑）的有效性。方法从灵敏度、敏感性、常见载体的影响、唾液斑保存时间的影响,以及与STR检验的相关性等几个方面进行研究。结果0.01 ul唾液和阴干保存1年以上的唾液斑仍能被有效检出,该检验对其它常见体液（斑）反应不敏感,常见载体对该检验无影响。结论菲德倍斯试剂是人唾液（斑）检验的理想试剂。     

杯口边缘附着微量口唇脱落细胞的检验

目的　探讨对遗留在杯口边缘的微量口唇黏膜脱落细胞进行DNA分型的可行性及影响因素 ,为案件的侦查提供指导作用。方法　分类提取饮水后容器边缘口唇黏膜脱落细胞中的DNA ,应用荧光标记PCR STR分型技术进行DNA分析。根据每个样本DNA基因座的检出个数 ,分别计算出基因座检出率。结果　不同容器、不同饮料对口唇黏膜脱落细胞DNA检验的影响不同。结论　杯口遗留的口唇黏膜脱落细胞 ,可作为一种法庭生物检材进行DNA分析 ,在实际办案中占有一席之地     

wizard clean up在混合斑DNA检验中的应用

目的建立一种快速、简单、有效的混合斑DNA检验方法。方法在100例检案中,利用wizardcleanup直接对精子消化液进行纯化浓缩。采用profilerplus试剂盒进行复合扩增,产物经ABI310基因分析仪检测。结果从混合斑中成功获得精斑10个STR位点的DNA分型。结论wizardcleanup处理混合斑,能有效去除女性成份,得到精斑DNA进行分型。     

The efficiency of Y-chromosome markers in forensic trace analysis and their inclusion in the Austrian National DNA Database

Y-STR markers are a valuable tool in the analysis of biological traces in which a mixture of male and female trace material is to be expected. It is possible to generate a Y-chromosome DNA profile, even if all the prior sperm tests are negative and no sign of any male component is found in amelogenin. In 38 of a total of 239 sexual offences a perpetrator trace was identified solely using Y-STR analysis. Based on these findings, the Austrian National DNA Database was expanded to include Y-STRs in 2012 with the primary objective to identify serial sexual offences.     

应用常染色体STR预测近亲关系调查案件

目的通过两起案例讨论利用常染色体STR全不同基因座数预测血亲关系,从而快速、高效地侦破疑难案件。方法应用全不同基因座数预测血亲关系,包括预测叔侄、祖孙或半同胞关系;应用IBS评分预测全同胞关系;结合家系调查、侦查信息调查案件。结果这种侦查模式有助于预测目标的同胞、叔侄、祖孙等血亲关系人,可充分挖掘样本的亲缘遗传信息,指导案件侦查方向。结论应用常染色体STR全不同基因座计数法和共有等位基因计数法可帮助预测血亲关系,能为调查案件提供新思路,对侦查更具指导意义。     

Estimating the probability of allelic drop-out of STR alleles in forensic genetics

In crime cases with available DNA evidence, the amount of DNA is often sparse due to the setting of the crime. In such cases, allelic drop-out of one or more true alleles in STR typing is possible. We present a statistical model for estimating the per locus and overall probability of allelic drop-out using the results of all STR loci in the case sample as reference. The methodology of logistic regression is appropriate for this analysis, and we demonstrate how to incorporate this in a forensic genetic framework.     

定量PCR技术在法医学中应用的研究

目的研究荧光定量PCR技术在法医学中的应用。方法应用Taqman技术对法医各种生物检材进行DNA定量。结果该定量PCR技术对各种法医生物检材进行了准确定量,并判断检材中是否存在抑制物,从而指导了后续STR的检验。结论定量PCR技术是法医DNA检验中一项不可缺少的辅助技术。     

Forensic databases,a perspective from the penitentiary centers of Spain

Scientific and technological progress in the field of forensic genetics is very useful in the resolution of criminal cases, but it entails the need for a deep ethical reflection, as the individual Fundamental Rights may be violated.This project aims to collect and compare the opinion of prisoners and prison officials on what characteristics the country's forensic database should have. In this context, 210 subjects were surveyed, 101 of them prisoners and the rest prison officials, from three different Spanish penitentiary centers.Among the results obtained, most prisoners and officials consider the national DNA database to be useful, and additionally, a 40% of the participants would support the integration of the profiles of the entire population. 64% considered it ethical to use the DNA profiles of the database as a tool for familial searching. Despite this, half of the respondents are concerned about the future uses of the DNA database.Integrating the opinion of these analyzed groups with other relevant judicial, scientific and ethical convictions, ensures the regulation between security and individual’s Human Rights.     

1066例新疆汉族人群21个常染色体STR基因座遗传多态性分析

目的研究21个常染色体STR基因座(CSF1PO,D3S1358,D5S818,D7S820,D8S1179,D13S317,D16S539,D18S51,D21S11,FGA,TH01,VWA,D2S1338,D19S433,D1S1656,D12S391,D2S441,D10S1248,TPOX,D22S1045,SE33)在新疆汉族人群中的遗传多态性。方法用GlobalFiler^TM R PCR Amplification荧光标记试剂盒对1066例新疆汉族无关个体的DNA进行PCR扩增,3500遗传分析仪电泳分析,用GeneMapper■ID-X v1.4软件分析等位基因片段大小,用Modified-Powerstates和Arlequin v3.5分析软件进行等位基因频率和法医学常用参数统计分析。结果在新疆汉族人群中,21个常染色体STR基因座不存在连锁不平衡现象,基因型分布符合Hardy–Weinberg平衡,共检出282个等位基因和1147种基因型,杂合度期望值(He)范围从0.6291(TPOX)到0.9428(SE33),多态信息含量(PIC)范围从0.5648(TPOX)到0.9393(SE33),累计个体识别率(CDP)>0.99999999999999999999。结论新疆汉族人群21个常染色体STR基因座具有较高多态性,可以用于法医学亲权鉴定和个体识别,也可以用于人类学和遗传学研究。     

Automated DNA extraction using the QIAsymphony platform: Estimation of DNA recovery from simulated forensic stains

The aim of this study was to evaluate the forensic protocol recently developed by Qiagen for the QIAsymphony automated DNA extraction platform. Samples containing low amounts of DNA were specifically considered, since they represent the majority of samples processed in our laboratory. The analysis of simulated blood and saliva traces showed that the highest DNA yields were obtained with the maximal elution volume available for the forensic protocol, that is 200 μl. Resulting DNA extracts were too diluted for successful DNA profiling and required a concentration. This additional step is time consuming and potentially increases inversion and contamination risks. The 200 μl DNA extracts were concentrated to 25 μl, and the DNA recovery estimated with real-time PCR as well as with the percentage of SGM Plus alleles detected. Results using our manual protocol, based on the QIAamp DNA mini kit, and the automated protocol were comparable. Further tests will be conducted to determine more precisely DNA recovery, contamination risk and PCR inhibitors removal, once a definitive procedure, allowing the concentration of DNA extracts from low yield samples, will be available for the QIAsymphony.     

天津地区朝鲜族9个STR基因座遗传多态性

目的　调查天津地区朝鲜族人群无关个体 9个STR基因座 (D3S135 8、vWA、FGA、D8S1179、D2 1S11、D18S5 1、D5S818、D13S17、D7S82 0 )多态性分布 ,研究其在法医学检验中的应用。方法　应用AmpFLSTR○R　ProfilerPlusTM荧光标记复合扩增系统对 184例天津地区朝鲜族无关个体血样DNA进行 9个STR基因座的复合扩增 ,用ABI310遗传分析仪对扩增产物进行检测 ,用GeneScan、GenoTyper软件进行基因分型 ,统计计算 9个STR基因座的群体遗传学参数。结果　该群体上述 9个STR基因座检出的等位基因及其基因型多态性分布良好 ,经校验 ,符合Hardy Weinberg平衡定律 ,累计个体识别力 (TDP)为 0 99999999996 ,偶合率为 4 .0 6×10 - 11,累积非父排除能力 (PE)为 0 9899。结论　上述 9个STR基因座适用于本地区该群体各类案件的法医学个体识别和亲权鉴定。     

A stochastic model of the processes in PCR based amplification of STR DNA in forensic applications

In forensic DNA profiling use is made of the well-known technique of PCR. When the amount of DNA is high, generally unambiguous profiles can be obtained, but for low copy number DNA stochastic effects can play a major role. In order to shed light on these stochastic effects, we present a simple model for the amplification process. According to the model, three possible things can happen to an individual single DNA strand in each complete cycle: successful amplification, no amplification, or amplification with the introduction of stutter. The model is developed in mathematical terms using a recursive approach: given the numbers of chains at a given cycle, the numbers in the next can be described using a multinomial probability distribution. A full set of recursive relations is derived for the expectations and (co)variances of the number of amplicon chains with no, 1 or 2 stutters. The exact mathematical solutions of this set are given, revealing the development of the expectations and (co)variances as function of the cycle number. The equations reveal that the expected number of amplicon chains without stutter grows exponentially with the cycle number, but for the chains with stutter the relation is more complex. The relative standard deviation on the numbers of chains (coefficient of variation) is inversely proportional to the square root of the expected number of DNA strands entering the amplification. As such, for high copy number DNA the stochastic effects can be ignored, but they play an important role at low concentrations. For the allelic peak, the coefficient of variation rapidly stabilizes after a few cycles, but for the chains with stutter the decrease is more slowly. Further, the ratio of the expected intensity of the stutter peak over that of the allelic peak increases linearly with the number of cycles. Stochastic models, like the one developed in the current paper, can be important in further developing interpretation rules in a Bayesian context.     

亲子鉴定中STR位点数选择及其应用价值研究

目的对在亲子鉴定中STR位点数的选择及其鉴定应用价值进行研究。方法将CODIS13个STR位点分为四个观测组,观测对象包括排除亲权的母亲-孩子-假设父亲三人组合102例,以及肯定亲权的母亲-孩子-假设父亲三人组合100例,通过310遗传分析仪对荧光复合扩增产物进行分型检测。结果各STR观察组出现的最低排除指标数与各观察组累积非父排除概率(CPE)值成一定正相关性,CPE值超过99.99%的两个STR观察组其出现的最低排除指标数为三个,同时这两个STR观察组在肯定亲权的案例分析中,其亲子关系概率值(RCP)值都超过了99.99%。结论对于亲子鉴定中的STR位点检测系统,其非父排除指标应为三个以上,其累积非父排除概率(CPE)值达到99.99%时,就可以认为该STR位点检测系统具有了相关的鉴定应用价值。