利用Identifiler分型系统推断同胞关系

目的探讨自主开发的同胞关系鉴定自动分析软件（ASI）对Identifiler分型系统进行同胞关系鉴定的可行性。方法应用本课题组所开发的软件ASI,对151对同胞及31 224对人工模拟无关个体进行Identifiler系统的15个常染色体STR基因座分型进行分析,计算亲权指数（PI）、同胞关系概率（WFS）和等位基因匹配情况,所获数据进行统计分析,自动计算排序。结果当WFS大于99.999%时,同胞个体占39.07%,无关个体占0%,两组具有显著差异,可以推断两个体同胞关系。当WFS介于1%~99.999%范围内,同胞个体和无关个体有部分重叠,同胞个体占60.93%,无关个体占21.3%,两者具有一定差异,可以通过增加检测STR基因座,再结合案情加作Y-STR、m tDNA检测,以推断两个体是否具有同胞关系。当WFS小于1%时,同胞个体占0%,无关个体占78.7%,可以推断两个体不具有同胞关系。个体间等位基因匹配结果表明：在检测Identifiler体系15个STR基因座时,当两个体常染色体STR基因座的全相同数目≥5时,或全不同数目≤1时,提示为同胞关系;当两个体全不同数目≥6时,或全相同数目≤1时,提示为无关个体,以此作为预测有无同胞关系的界值。结论Identifiler系统及同胞关系鉴定自动分析软件ASI可用于推断同胞关系。     

ITO法和判别函数法在同胞关系鉴定中的应用

目的探讨ITO法和判别函数法在全同胞、半同胞关系鉴定中的应用价值。方法根据500对全同胞、50对半同胞及500对无关个体的15个STR基因座（PowerPlex^TM 16体系）的分型结果,采用ITO法分别计算全同胞关系指数（FSI）、半同胞关系指数（HSI）及其比值（FSI：HSI）。比较三组配对个体的等位基因匹配情况,计算分型结果全不同的基因座数（x0）、半相同的基因座数（x1）和完全相同的基因座数（x2）,利用SPSS 13．0分析软件建立全同胞、半同胞和无关个体的判别函数。结果（1）以FSI≥19、FSI〈1作为全同胞与无关个体的判别标准,交互准确率为96.4％;以HSI≥19、HSI〈I作为半同胞与无关个体的判别标准,交互准确率为85.3％;以FSI：HSI≥1、FSI：HSI〈1作为全同胞与半同胞的判别标准,交互准确率为87．5％。（2）分别建立了全同胞-半同胞-无关个体、全同胞-无关个体、半同胞-无关个体、全同胞-半同胞4组判别函数．判别函数交互准确率为84．4％～97．7％,其中同胞-无关个体判别准确率最高。结论ITO法与判别函数法在全同胞、半同胞鉴定中均具有较高的应用价值。     

IBD法在堂表亲缘关系鉴定中的应用

目的使用血缘一致性(identity by descent,IBD)法计算堂表亲缘关系的堂表关系指数(first cousin index,FCI)和累积堂表关系指数(combined first cousin index,CFCI),为IBD法鉴定两个个体是否具有堂表亲缘关系提供科学手段。方法取124对堂表兄弟姐妹和186对无亲缘关系个体的口腔拭子,检验每人18个常染色体STR基因座的等位基因,用IBD法计算堂表对和无关个体对的FCI和CFCI,并用判别分析的方法对两组样本的FCI和CFCI计算结果进行分析。结果 CFCI在堂表对和无关个体对中的频率分布呈偏正态分布,前者的平均值和标准差为11.864和21.678,后者为0.605和0.988,两者具有显著差异。以CFCI/(CFCI+1)≥0.6为标准,堂表对和无关个体对判别准确率为88.387%;依据各常STR基因座的FCI计算结果建立判别方程,多元判别方程和多元逐步判别方程的判别准确率分别为92.258%和91.935%。结论用IBD法和依据IBD建立的判别分析法可以用于堂表亲缘关系的筛选。     

采用家系基因型重建法鉴定半同胞关系1例

<正>对于祖孙、叔侄、同胞、半同胞等隔代基因遗传的亲缘关系鉴定,可采用ITO法计算似然率值LR进行判断[1]。然而在某些特定的案例中,采用ITO法,即使大量增加STR基因座检测数,也不能有效提高LR值,可采用家系基因型重建法[2-3],以便获得确定亲缘关系的支持证据。本文通过1例半同胞鉴定案例,介绍该分析方法为同行参考。1案例鉴定1.1简要案情本实验室受理1例因遗产纠纷需进行半同胞亲     

常染色体STR遗传标记在同胞鉴定中的应用

目的 探讨常染色体STR遗传标记用于鉴定两个体同胞关系的可行性。方法 用Power Plex~(TM)16体系15个STR基因座检测150对同胞个体和150对无关个体,ITO法计算同胞关系指数(PI_(FS))与同胞关系概率(W_(FS)),并比较两组W_(FS)值及两个体间等位基因匹配情况的差异,对前者进行组间差异的x~2检验。结果 100对(66.67％)同胞个体的W_(FS)大于0.9995;无关个体W_(FS)均小于0.8,其中100对(66.67％)W_(FS)小于0.27。同胞个体两个体间等位基因全相同的基因座个数为1～10个不等,平均5.49个,无关个体0～5个不等,平均1.33个;等位基因全不同的基因座个数,同胞个体0～6个不等,平均1.66个,无关个体2～11个不等,平均6.57个;等位基因半相同的基因座个数,同胞个体3～13个不等,平均7.85个,而无关个体1～13个不等,平均7.11个。经x~2检验,同胞个体和无关个体间全相同和全不同的基因座数差异均有极显著意义(P<0.001),半相同的基因座数差异无显著意义(P>0.05)。结论 PowerPlex~(TM)16体系可用于鉴定同胞关系。当两个体全不同基因座个数大于或等于6个,或全相同基因座数为0时,提示为无关个体;当两个体全不同基因座个数小于或等于1个,或全相同基因座数大于或等于6个时,提示为同胞。     

X-STR分型用于亲缘关系鉴定的似然率计算

目的推导X染色体短串联重复序列(X-short tandem repeat,X-STR)分型用于两个体间亲缘关系鉴定的似然率计算公式。方法根据不同亲缘关系的两个体间的血缘同一系数获得两个体特定的联合基因型概率(X值),计算两无关个体特定的联合基因型概率(Y值),从而求得似然率(X/Y)。结果推导出女性-女性、女性-男性、男性-男性个体间不同亲缘关系各种基因型组合的似然率计算公式,并通过案例验证。结论推导的根据X-STR分型计算两个体间亲缘关系的似然率计算方法简便、准确,为X-STR基因座在疑难亲缘关系鉴定中发挥其更大应用价值奠定了基础。     

51个常染色体STR基因座在ITO法判断全同胞中的应用

目的探讨ITO法和判别函数法在全同胞鉴定中的应用价值。方法根据342对全同胞和3 900对无关个体的19、21、39、51个常染色STR基因座的分型结果,采用ITO法计算全同胞关系指数(FSI)。用SPSS软件Fisher判别分析法,分别建立lg FSI全同胞-无关个体的判别函数。结果每组全同胞对和无关个体对的lg FSI符合正态分布,具有显著性差异。在19、21、39、51个STR基因座,全同胞组判别函数分别为L同胞=1.666 6×lg FSI-5.208 0,L同胞=1.643 9×lg FSI-5.512 0,L同胞=1.569 4×lg FSI-8.076 4,L同胞=1.480 7×lg FSI-9.860 9;无关个体组分别为L无关=-1.346 1×lg FSI-3.638 5,L无关=-1.330 9×lg FSI-3.851 7,L无关=-1.319 2×lg FSI-5.910 2,L无关=-1.273 8×lg FSI-7.477 6。平均错判率分别为:1.361 9%、1.228 5%、0.438 6%和0.146 2%。结论 ITO判别函数法在全同胞-无关个体鉴定中具有很高的应用价值,且检测基因座越多,系统效能越高,并能降低错判风险。     

多种遗传标记分析在1例半同胞鉴定中的综合应用

目的通过对1例半同胞亲缘关系的检验,探讨多种遗传标记在同父异母半同胞关系鉴定中的应用。方法分别使用39个常色体STR遗传标记、23个Y染色体STR遗传标记、12个X染色体STR遗传标记对赵3、赵4、赵5与赵1、赵2是否为半同胞亲缘关系进行检验。结果依据常染色体、Y染色体及X染色体STR的分型结果,采用家系基因型重建的方法可以推断出赵4(可疑半同胞)与赵1、赵2之间系无关个体,支持赵3(可疑半同胞)、赵5(可疑半同胞)与赵1、赵2为同父异母半同胞关系。结论对于同父异母的半同胞鉴定,综合应用多种遗传标记,并采用家系基因型重建的方法进行分析可获得较为可靠的鉴定意见,仅使用ITO法计算半同胞指数或判别函数法分析则难以提供可靠的鉴定意见。     

依据共有STR基因座数判别全同胞关系

目的建立并探讨基于共有STR基因座数的全同胞关系判别方法。方法根据280对全同胞（fullsibling,FS）及2 003对无关个体（unrelated individual,UI）Identifiler系统15个STR基因座的分型结果,采用计数法计算全不同基因座数（A0）、半相同基因座数（A1）和全相同基因座数（A2）,依据ITO法计算每对受试者的全同胞指数（FSI）,应用判别分析得出基于共有基因座数或FSI进行全同胞及无关个体关系判别的Fisher判别函数,并比较其判别效能。结果全同胞对中的A1、A2和无关个体对中的A0、A1均呈正态分布,全同胞对中的A0和无关个体对中的A2均呈偏态分布。A1在两组人群中的分布差异无统计学意义（P〉0.01）。同时采用A0和A2建立的全同胞及无关个体关系的判别函数分别为ZFS=0.99817A0＋4.24442A2-12.77970和ZUI=2.014 56 A0＋1.546 58 A2-7.280 76。采用上述判别函数进行全同胞及无关个体关系判别的平均错判率为0.049 0。上述判别函数的判别效能与基于FSI的判别函数的判别效能差异无统计学意义。结论可以采用Identifiler系统的共有基因座数进行全同胞及无关个体关系的判别,所建立的判别公式的判别效能与经典ITO法相近。     

vWA和D12S391基因座在亲缘关系个体中的连锁分析

本研究运用sinofiler及Plower Plex 21商品化试剂盒检测中南地区父-子样本230对,无关个体440例,对v WA、D12S391二个基因座分别于亲缘关系个体与无关个体进行连锁不平衡检验。结果父-子样本在v WA与D12S391之间呈现统计学意义(P0.05),中南地区无关个体未表现显著的连锁不平衡(P0.05)。在v WA与D12S391二个基因座应用于无关个体匹配概率计算时,其影响可忽略;应用于法庭科学亲缘关系鉴定时,该二个基因座之间存在连锁不平衡将导致似然率计算结果偏离。     

亲权指数和个体识别似然比计算软件的开发与应用

目的建立计算亲子鉴定亲权指数(PI)和个体识别似然比(LR)的计算软件。方法依据相关行业规范和文献中给出的计算方法,利用计算机语言Visual Basic 6.0编写程序。结果开发出适用于PI和LR的计算软件。结论该计算软件可以帮助工作人员提高计算效率,服务法医物证工作。     

Using STR,MiniSTR and SNP markers to solve complex cases of kinship analysis

In complex kinship investigation, miniSTRs and SNPs have been frequently used in order to increase the likelihood ratio (LR), when the results obtained for the most commonly used STR multiplexes were not informative enough. In this work, we describe the results obtained when using a battery of 23 STRs, 3 miniSTRs and 52 SNPs to investigate three complex paternity cases where the father was not available, and one paternity case with bone samples, from which no results could be obtained for STRs (including the 3 miniSTRs, D10S1248, D14S1434 and D22S1045). In all cases, the additional information provided by the SNPforID 52plex identification panel was enough to achieve conclusive results.     

Resolving paternity relationships using X-chromosome STRs and Bayesian networks

X-chromosomal short tandem repeats (X-STRs) are very useful in complex paternity cases because they are inherited by male and female offspring in different ways. They complement autosomal STRs (as-STRs) allowing higher paternity probabilities to be attained. These probabilities are expressed in a likelihood ratio (LR). The formulae needed to calculate LR depend on the genotype combinations of suspected pedigrees. LR can also be obtained by the use of Bayesian networks (BNs). These are graphical representations of real situations that can be used to easily calculate complex probabilities. In the present work, two BNs are presented, which are designed to derive LRs for half-sisters/half-sisters and mother/daughter/paternal grandmother relationships. These networks were validated against known formulae and show themselves to be useful in other suspect pedigree situations than those for which they were developed. The BNs were applied in two paternity cases. The application of the mother/daughter/paternal grandmother BN highlighted the complementary value of X-STRs to as-STRs. The same case evaluated without the mother underlined that missing information tends to be conservative if the alleged father is the biological father and otherwise nonconservative. The half-sisters case shows a limitation of statistical interpretations in regard to high allelic frequencies.     

A molecular classification of moles and its use in filiation tests

Pregnancies, including ones that follow sexual assaults, occasionally produce hydatidiform moles. The alleged fathers (AFs) of moles have been tested for paternity by identifying the mole's locus phenotype—the one or two visible paternal obligate alleles (POAs) per locus. The probability that the mole inherited the POAs from the AF was divided by the probability that the mole inherited the POAs from a random man. This likelihood ratio (LR) would increase if the mole's specific genotype was known. Moles are generated in five different ways that produce five distinct genotypes. Examining a mole's multilocus STR profile reveals a mole's pathogenesis, determines locus genotypes, and increases paternity LRs.     

Investigation of 74 microhaplotypes for kinship testing in US populations

Microhaplotypes are markers that consist of haplotype blocks of SNPs, which can be analyzed by massively parallel sequencing technologies. These allow determining the haplotype phase at every locus by clonal sequencing each DNA strand. MHs are polymorphic loci with same size alleles, no stutter, and lower mutation rate than STRs. They can provide the same power of discrimination of STR-kits, thus useful for mixture deconvolution, but more accurate ancestry prediction than STRs. In this study we investigated the potential of a recently developed 74plex-MH panel for kinship testing using the Familias software.Samples from families of four major US population groups were collected and genotyped using the 74plex-MH panel. MH allele frequency data from 347 individuals were imported into Familias software along with STR allele frequency data of 29 loci (NIST dataset) from 1036 individuals. Different family scenarios were tested and these included unrelated vs parent-child, unrelated vs full siblings, unrelated vs half siblings, unrelated vs cousin pairs. The prediction of the kinship relation for the four populations of interest was reported as Log10 of the likelihood ratio (LR).Overall, the panel of 74MHs and 29STRs showed similar performance in predicting the correct kinship scenarios tested. Correct prediction was reported for parent-child, full siblings, and half sibling scenarios, but not for the cousin pairs scenario. The panel of 74 MHs showed larger Log10LR values than the 29 STR-assay, thus demonstrating the effectiveness of this biomarker as a tool for kinship testing in addition to mixture deconvolution and ancestry prediction.     

A X-chromosome STR hexaplex as a powerful tool in deficiency paternity cases

The X-chromosome short tandem repeat (STR) markers have been described as very adequate tools for solving deficiency paternity cases and kinship tests when women are involved. In the absence of the alleged father, presumed paternal relationship can be more efficiently investigated by using a set of six to ten X-STR markers compared to fifteen autosomal STR. For this study, we compared the usefulness of a X-STR hexaplex developed in our laboratory (DXS7133, DXS7424, DXS8378, DXS6807, DXS7423 and DXS8377) and the commercial kit Identifiler in solving deficiency paternities. We have worked on distinct groups of caseworks involving daughters, their mothers and presumed paternal grandmothers or putative half sisters and their respective mothers. The PCR products were separated by capillary electrophoresis and detected in an ABI Prism 3100. In the majority of the caseworks (>90%), the likelihood ratio (LR) obtained by using the X-STR hexaplex was higher than the LR value observed when the Identifiler kit was used for genotyping. The combination of the two STR typing systems was able to solve all the cases.     

单亲案亲权鉴定结果判定策略

目的探讨用STR基因座进行单亲鉴定出现矛盾基因座时下结论的策略。方法根据基因频率和遗传规律,推导单亲案亲权鉴定时的非父排除率。根据平均单亲非父排除率和平均突变率,用二项分布公式分别计算出现不同数目矛盾基因座时真父和假父的概率和似然率(亲权指数)。结果对STR共显性基因座,其单亲非父排除率的计算公式为:PEM=∑i=n1pi2(1-pi)2 ∑i相似文献   

两个个体间常用亲缘关系指数的统一算法

目的 介绍仅有两名被鉴定人时二者间常见亲缘关系指数的统一算法.方法 以ITO法计算二联体亲权指数(paternity index in duos,PID)、全同胞指数(full sibling index,FSI)、半同胞指数(half sibling index,HSI)、叔侄指数(avuncular index,A...     

DNA亲缘关系数据分析管理系统的开发与应用

选用C／S（客户端／服务器）模式,采用SQLServer2000数据库,设计出一套适合实验室使用的DNA亲缘关系分析处理系统,使之包含案件登记及数据录入、亲权指数及相对亲权关系概率计算、基础数据库及档案管理三大模块。经过多次实验证明DNA亲缘关系分析处理系统能用于同胞及其他亲缘关系鉴定案例的分析处理,并具有档案管理的功能,能提高鉴定工作效率和工作质量。     

Information‐Theoretical Assessment of the Performance of Likelihood Ratio Computation Methods

Performance of likelihood ratio (LR) methods for evidence evaluation has been represented in the past using, for example, Tippett plots. We propose empirical cross‐entropy (ECE) plots as a metric of accuracy based on the statistical theory of proper scoring rules, interpretable as information given by the evidence according to information theory, which quantify calibration of LR values. We present results with a case example using a glass database from real casework, comparing performance with both Tippett and ECE plots. We conclude that ECE plots allow clearer comparisons of LR methods than previous metrics, allowing a theoretical criterion to determine whether a given method should be used for evidence evaluation or not, which is an improvement over Tippett plots. A set of recommendations for the use of the proposed methodology by practitioners is also given.