Two-man and two-sibling paternity cases.

Traditional genetic marker systems rarely fail to resolve paternity disputes when two or more men are accused, except when men are brothers. A sibling of the biologic father may not be excluded by these laboratory tests and sometimes yields calculated odds of paternity that are equal to or higher than the true male parent. Resolved two-brother cases were compared with resolved cases involving two unrelated men. In each case, the residual odds of paternity were determined for each man and the greater was divided by the lesser to produce a paternity fraction. The paternity fraction is a useful indicator of biologic parentage when it exceeds a value of 10 (log10 of-the-odds score greater than or equal to 1). Tests for alleles at highly heterozygous loci are indicated in initial laboratory evaluations of cases involving brothers. Human leukocyte antigen and variable number of tandem repeat polymorphisms appear suitable.     

Deduction of paternity index from DNA mixture

Determination of individual genotypes in DNA mixture remains a challenge in forensic science. Using an approach of mixture of distributions, this article provides formula for calculation of paternity index (PI) in cases where only tissue mixture of the mother and alleged father, the genotypes of the mother and child, but not that of the alleged father are available. The formula has been used to solve a real case using mother's vaginal tissue contaminated with semen from alleged father.     

X-chromosome STR typing in deficiency paternity cases

It is presented a deficiency paternity casework where the ChrX-STRs were crucial to solve the case. Twenty-two autossomal STRs studied in biological samples from a child, his mother and alleged paternal grandmother and grandfather revealed insufficient information to provide a clear conclusion. Fifteen additional ChrX-STRs confirmed the exclusion of the putative father.     

STR等位基因频率对父权指数的影响

目的观察中国汉族不同人群STR等位基因频率对联合父权指数(CPI)的影响。方法随机取108例13个CODIS基因座分型结果不排除父权关系的三联体案和二联体案,用5个不同地区人群的等位基因频率计算CPI值。结果三联体案的CPI值在2077.63～50897711626.46之间,同一案例的最大CPI与最小值CPI之比大于100者有20例(19.52%);二联体案的CPI值在25.12～2998685141之间,同一案例的最大CPI与最小值CPI之比大于100者有13例(12.04%)。结论不同人群等位基因频率计算CODIS基因座所得的CPI值在部分亲权鉴定案中有很大的差异。为了防止等位基因频率不确定性带来的误差,建议在亲权鉴定中用保守法计算CPI值。     

HLA investigations in paternity cases showing incompatible homozygosity

Incompatible homozygosity is seen when either the putative father is homozygous for a gene which the child lacks or when the child is homozygous for a gene which is absent from the putative father.Sixty-nine cases of paternity with incompatible homozygosity between child and putative father are reported. These cases were investigated in the HLA system and the results obtained are presented.     

Introduction of a standardized "paternity index" for the statistical evaluation of blood group findings in paternity testing

The introduction of a standardized paternity index (PI) for the statistical evaluation of blood group findings in cases of disputed paternity is proposed and explained. By using the PI $\text{X}\text{Y}$ as parameter, it is not necessary to give the information of the probability of paternity in percent. The PI includes the full information of the blood group findings. In addition to that, by using the suggested standardization based on the probabilities of error according to Schulte Mönting and Walter the test volume is also taken into account. The interpretation of the mathematical result is given by verbal predicates, the limitations of which are orientated by the verbal predicates for the probabilities of error according to Schulte Mönting and Walter, published by us elsewhere. Besides the essential fact that the test volume is taken into account, the most important advantage of this procedure is that the mathematical result is involved in the court decision only by the PI (which is free of any valuation) and its verbal predicate and not by sometimes relatively high percentages, which may be misunderstood by laymen.     

2例亲权鉴定案中的嵌合体STR谱分析

先天性基因嵌合体由遗传获得，是胚胎早期两个不同受精卵相互混合或血管交叉吻合继而发育成的一个包含两套（种）不同细胞系的个体。分为血型嵌合体（twin chimeras）和全身器官组织嵌合体（whole body chimerasl两种。本文通过两例亲权鉴定中发现的男性先天性嵌合体及其家族成员常染色体、性染色体的STR谱遗传分析，探讨先天性基因嵌合体的类型、发生、基因嵌合现象在不同组织中的表现及其作为证据可能在法庭科学调查中存在的风险。分析结果表明，两例男性Y—STR单倍型显示正常，分别与其男性家族成员Y—STR单倍型一致。但其在常染色体和X染色体上的STR基因表现嵌合现象，分别是在胚胎发育早期由男性-女性、男性-男性的异卵双生子发生融合并发育而成的的全身器官组织嵌合体。嵌合体上不同来源组织的STR等位基因强度显示不均衡状态。     

Beyond traditional paternity and identification cases. Selecting the most probable pedigree

The paper extends on the traditional methodology used to quantify DNA evidence in paternity or identification cases. By extending we imply that there are more than two alternatives to choose between. In a standard paternity case the two competing explanations H(1): "John Doe is the father of the child and H(2): "A random man is the father of the child, are typically considered. A paternity index of 100000 implies that the data is 100000 more likely assuming hypothesis H(1) rather than H(2). If H(2) is replaced by "A brother of John Doe is the father", the LR may change dramatically. The main topic of this paper is to determine the most probable pedigree given a certain set of data including DNA profiles. In the previous example this corresponds to determining the most likely relation between John Doe and the child. Based on DNA obtained from victims of a fire, bodies found in an ancient grave or from individuals seeking to confirm their anticipated family relations, we would like to determine the most probable pedigree. The approach we present provides the possibility to combine non-DNA evidence, say age of individuals, and DNA profiles. The program familias, obtainable as shareware from http://www.nr.no/familias, delivers the probabilities for the various family constellations. More precisely, the information (if any) prior to DNA is combined with the DNA-profiles in a Bayesian manner to deliver the posterior probabilities. We exemplify using the well published Romanov data where the accepted solution emerges among 4536 possibilities considered. Various other applications based on forensic case work are discussed. In addition we have simulated data to resemble an incest case. Since the true family relation is known in this case, we may evaluate the method.     

随机模拟法进行单亲累积亲权指数分析

目的以随机模拟法进行大量单亲累积亲权指数(CPI)统计分析。方法针对Identifiler、PP18D、PP21、AGCU EX20、AGCU 21+1等5个试剂盒,使用自主研发软件,随机模拟100万组单亲组合并计算单亲PI,统计各试剂盒单亲极低CPI比率(R_(VLCPI))、各基因座的PI中位数(M_(PI))和39个基因座的平均单基因座单亲PI(PI_(solo)),并推导增加检测的基因座个数(N)的计算公式。结果 Identifiler、PP18D、AGCU EX20、PP21、AGCU EX20AGCU 21+1的R_(VLCPI)分别为24.9%、6.5%、1.4%、0.7%、0.000 1%。在各试剂盒的基因座存在包含关系的前提下,R_(VLCPI)和常染色体基因座数成负相关。PI_(solo)为1.843 2。M_(PI)与PE_(duo)呈显著的正相关(r=0.956,P0.001)。增加检测的基因座个数公式为N=「log_(1.843 2)(10 000/P)■。结论本文结果和公式对单亲鉴定案具有一定的应用价值。     

三联体亲权指数的统一算法及其扩展应用

目的介绍一种在生母参与情形下,孩子与被鉴定人间常用亲缘关系指数的统一算法。方法以计算三联体亲权指数（paternity index in trios,PIT）的公式为基础,分析不同亲缘关系指数计算公式中的公因子,并以此公因子对不同情形下PIT计算公式进行统一描述,采用叔伯指数定律和亲缘系数（r）将上述PIT统一计算公式扩展至祖孙、半同胞、叔侄及第一代堂兄弟等不同情形下的亲缘关系指数的运算。结果以状态一致性等位基因的频率倒数加1为公因子,在引入亲缘系数（r）的情形下,获得了可计算在生母参与时,孩子与被鉴定人间任意亲缘关系指数的两个公式。结论在生母参与情形下,孩子与被鉴定人间亲缘关系指数的统一算法简化了运算过程,有利于编程实现批量计算。     

DNA profile evidence in complex disputed paternity cases: The analysis of 300 real cases

In disputed paternity cases where the putative father is unavailable DNA from one or more of his relatives could be used. However, interpreting results is often difficult, because of the partial information regarding the parental genotype obtained from his relatives. We analyzed results obtained in 300 real paternity cases performed through close relatives of the real father (sib, half-sibs, one grandparent and/or uncle). DNA was typed with PowerPlex (Promega) and the LR estimated with the Software BDGen. As expected the higher LR values were achieved with sibs and half-sibs (in such cases where his/her mother was available for testing). The LR values were tight related to the number of uninformative loci, which varied between 0 and 13. In 10% of the reviewed cases, 10 or more non-informative loci were observed; all of them associated LR values below 0.01. Thus, providing evidence in favor of no relatedness.     

Object-oriented Bayesian networks for paternity cases with allelic dependencies

This study extends the current use of Bayesian networks by incorporating the effects of allelic dependencies in paternity calculations. The use of object-oriented networks greatly simplify the process of building and interpreting forensic identification models, allowing researchers to solve new, more complex problems. We explore two paternity examples: the most common scenario where DNA evidence is available from the alleged father, the mother and the child; a more complex case where DNA is not available from the alleged father, but is available from the alleged father’s brother. Object-oriented networks are built, using HUGIN, for each example which incorporate the effects of allelic dependence caused by evolutionary relatedness.     

13个STR基因座在亲子鉴定案例中的基因突变观察

目的 观察美国 CODIS系统的 13个 STR基因座在532例认定亲子关系的亲子鉴定案中的基因突变情况,探讨STR基因座突变率及突变类型。方法 经“Profiler Plus”及“Cofiler”试剂盒检测的587例亲子鉴定案,对其中有1～2个STR基因座不符合遗传规律者,增加HLA等血型基因和“PowerPlex16~(TM)”试剂盒检测。必要时,还增加Y-STR基因座检测和HLA等位基因测序。结果 认定亲子关系的532例,观察1052次减数分裂,发现17例亲子鉴定中的18次基因突变事件,其中16例1个STR基因座的基因发生突变,1例2个STR基因座的基因发生突变;突变的基因座包括D5S818、D3S1358、D16S539、CSFIPO、D21S11、D13S317、D7S820、vWA、D18S51和FGA,其中以FGA和D18S51基因座的突变率最高(0.29％);18次突变事件,其中来自父亲11次,来自母亲5次,无法确定2次。结论 用美国CODIS系统的STR基因座进行亲子鉴定,在有1～2个基因座不符合遗传规律时,要综合分析,并增加其它的遗传标记进行检测。