The polymerase chain reaction and post-mortem forensic identity testing: application of amplified D1S80 and HLA-DQ alpha loci to the identification of fire victims.

The application of DNA typing methods after amplification by the polymerase chain reaction (PCR) of DNA derived from body tissues from charred fire victims was investigated. A total of 26 different tissue specimens from ten extensively burned individuals were analyzed. The samples included femoral muscle, psoas muscle, bone marrow and blood. The post-mortem period varied from 38 to 183 h. After amplifying the DNA by PCR from the various tissues, the D1S80 locus was analyzed with a high resolution polyacrylamide gel electrophoresis technique followed by silver staining and the alleles of the HLA-DQ alpha locus were detected by using a reverse dot blot format. All samples could be typed for both loci and the genotypes were consistent in the various tissues from each individual. A parentage test was performed in two cases and Mendelian inheritance of the alleles for both loci was observed.     

Population data for MiniNC01 in a population sample from North-eastern Italy and their use in neoplastic tissues fixed in formalin and embedded in paraffin

To establish a database for the three MiniNC01 loci D10S1248, D14S1434, D22S1045 in a population sample from North-eastern Italy, 102 unrelated individuals were typed. DNA was amplified in a multiplex reaction with subsequent automatic detection using capillary electrophoresis. The obtained data give a contribution to the definition of Italian population miniSTRs allele frequencies for the three analysed loci. These three MiniSTRs were tested on 21 neoplastic tissues and the obtained genotypes were compared to those obtained from normal tissue. Only 3 cases (14.28%) gave a different genotype suggesting a better performance of these markers than traditional STRs.     

肿瘤组织9个STR基因座及Amelogenin基因座突变

目的 探讨CODIS系统中的9个STR基因座及Amel基因座在肿瘤组织中的变异。方法 收集20个个体的肿瘤组织及其血样,Chelex100法提取DNA,用Profiler plus系统复合扩增,310型遗传分析仪检测。结果 检验的10个基因座均有基因发生突变;20个个体肿瘤组织有6个个体的基因发生突变,变异率超过30％;同一个体的肿瘤组织发生基因突变的基因座最多为6个。结论 慎用肿瘤组织作为医疗纠纷、失踪人员的检材及对照样本。     

福尔马林固定组织SNP与STR检测的比较

目的检测经长期福尔马林固定的组织降解情况,并比较组织中SNP与STR的检出率。方法本文对24例经福尔马林固定、-20℃保存5年的组织样本,采用Quantifiler?Trio DNA定量试剂盒检测样本DNA的降解系数及浓度,运用55-SNPs SNa Pshot复合分型体系和Power Plex?21试剂盒分别进行SNP与STR检测。结果大部分样本降解系数在1~8,发生不同程度的降解。与未降解样本相比,SNP分型完全一致,检出率为100%;其中8例样本STR分型存在33个等位基因丢失,降解系数均大于2.6,且75.8%的等位基因片段长度大于300bp。当样本检测出16个STR基因座时,似然率与54个SNP相当。当样本检出大于17个STR时,似然率大于54个SNP。STR基因座片段长度与等位基因检出率之间呈负相关。除2例样本降解系数较小却发生等位基因丢失外,其余样本降解系数与等位基因检出率之间呈负相关。结论经福尔马林长期固定的组织DNA易降解,检测SNP明显优于STR,但需要更多的SNP以提高个体识别能力。     

3种甲醛固定组织DNA提取方法的比较

目的对不同方法提取甲醛固定组织中DNA的效果进行比较,寻找一种操作简便、经济实用、质量较高的DNA提取方法。方法取甲醛固定的心肌组织14份,分别以改良酚-氯仿法,改良Trizol法,试剂盒法提取DNA,进行紫外分光光度计测定OD260/OD280值后,经PCR扩增,琼脂糖凝胶电泳分析确定提取的DNA质量。结果改良酚-氯仿法,改良Trizol法,试剂盒法OD260/OD280比值分别为1.841 5±0.380 4、1.370 5±0.336 7、0.831 6±0.175 0。两两比较均有显著性差异(P<0.05)。3种不同方法提取DNA含量分别为0.943 8±0.530 1、0.707 5±0.423 6、0.342 8±0.182 5。PCR扩增后琼脂糖凝胶电泳显示以改良酚-氯仿法所提DNA的谱带清晰度好于其它两种方法。结论改良酚-氯仿法简便有效,所用试剂价格低廉,是一种经济实用的甲醛固定组织DNA提取方法。     

AmpFlSTR Profiler Plus and AmpFlSTR COfiler analysis of tissues stored in GenoFix, a new tissue preservation solution for mass disaster DNA identification

A preliminary study was conducted to assess the capability of a new alcohol-based tissue fixative, GenoFix, to preserve DNA from biopsy tissues stored at room temperature and/or -20 degrees C in a freezer, for subsequent short tandem repeat (STR) DNA typing analysis. Fresh human smooth muscle samples were stored at room temperature in GenoFix for one month and up to one year and seven months before being processed using the megaplex STR systems, AmpFlSTR Profiler Plus and AmpFlSTR COfiler. Alternatively, muscle tissues in GenoFix were placed at -20 degrees C in a freezer for up to 3 1/2 years following two to three months in the fixative at room temperature. DNA analysis was also carried out on tissues stored in GenoFix for one month at room temperature and subsequently paraffin-embedded and stored at room temperature for four years. The AmpFlSTR Profiler Plus and AmpFlSTR COfiler STR profiles produced, using DNA extracted from all fixed tissue samples, were of very good quality. The fluorescent signals were well balanced across the nine STR loci or six loci comprised in the megaplexes surveyed and profiles showed no differences with those observed for the control blood of the respective donor patients. Continuous exposure to GenoFix at room temperature (up to one year and seven months) did not compromise the STR typing analysis of the fixed tissues. No adverse effects were noted on the STR typeability of tissues fixed with GenoFix and stored at -20 degrees C in a freezer for up to 3 1/2 years. STR profiles generated from the paraffin-embedded tissues fixed in GenoFix were of excellent quality. This preliminary study suggests that GenoFix can be used to store tissue samples at room temperature for up to one year and seven months or at -20 degrees C in a freezer for longer storage (up to 3 1/2 years). This new and odorless tissue fixative promotes tissue and DNA preservation in a very effective manner and as such may prove useful in criminal investigations or mass disaster identifications carried out in remote locations and in which a small or large number of tissue samples are collected for further analyses.     

13个STR位点在人消化系统肿瘤组织中的变异分析

目的探讨13个CODIS-STR基因座在人消化系统肿瘤组织中的变异情况。方法收集55个个体的消化系统肿瘤组织及其正常组织和血样,Chelex100法提取DNA,用Profiler试剂盒和Cofiler试剂盒进行复合扩增,310型遗传分析仪检测。结果55例肿瘤组织中均存在细胞分裂异常现象,其中有2例肿瘤组织的STR位点发生了变异,变异的类型包括基因型改变、杂合型丢失和杂合双峰不平衡,而且变异可以是多位点同时发生。结论对肿瘤组织类型的样品进行STR分析时,应多加慎重,因为排除的位点可能来自肿瘤组织中的基因突变。     

Heteroplasmy in hair: differences among hair and blood from the same individuals are still a matter of debate

The analysis of mitochondrial DNA (mtDNA) is a useful tool in forensic cases when sample contents too little or degraded nuclear DNA to genotype by autosomal short tandem repeat (STR) loci, but it is especially useful when the only forensic evidence is a hair shaft. Several authors have related differences in mtDNA from different tissues within the same individual, with high frequency of heteroplasmic variants in hair, as also in some other tissues. Is still a matter of debate how the differences influence the interpretation forensic protocols. One difference between two samples supposed to be originated from the same individual are related to an inconclusive result, but depending on the tissue and the position of the difference it should have a different interpretation, based on mutation-rate heterogeneity of mtDNA. In order to investigate it differences in the mtDNA control region from hair shafts and blood in our population, sequences from the hypervariable regions 1 and 2 (HV1 and HV2) from 100 Brazilian unrelated individuals were compared. The frequency of point heteroplasmy observed in hair was 10.5% by sequencing. Our study confirms the results related by other authors that concluded that small differences within tissues should be interpreted with caution especially when analyzing hair samples.     

人体组织在非缓冲福尔马林固定剂中的STR检测时限

目的评估经非缓冲福尔马林固定不同时间后的人体组织STR分型有效性,了解各种人体组织在非缓冲福尔马林固定剂中可获得完全STR分型位点的时限。方法市售40%福尔马林溶液经1∶9稀释后在室温(15～20℃)下固定人体组织,不同时间后取样。以QIAamp DNA法和IQTMDNA System法提取DNA,用quantifiler humanTaqman探针法进行DNA定量,用常规16 STR位点的AmpFSTR identifiler kit和短小片段9 STR位点的AmpFSTR Min-iFiler kit进行PCR扩增,在3100遗传分析仪进行扩增DNA片段长度检测,用GeneMapper ID v3.2对STR位点检出率进行分析。结果福尔马林固定时间、组织类型以及DNA提取方法、PCR的DNA模板终浓度均影响非缓冲福尔马林固定后人体组织STR分型效能。DNA提取用QIAgen法为优,DNA模板终浓度的最佳范围在1～3ng/μL。各类型组织在非缓冲福尔马林固定剂中的降解速率有差异,肺组织的降解速率最慢,肝、肠组织最快。固定时间在4d内的组织可以获得常规STR的完整位点数;固定时间在15d内的组织可以获得miniSTR的完整位点数。结论非缓冲福尔马林固定人体组织时间是影响STR分型的最主要因素,其次组织类型、提取方法、DNA模板浓度及STR基因座的选择也是此类降解样品成功检测的关键因素。     

Allele frequencies and haplotypes of 12 Y-STR loci for the local Chinese population in Hong Kong

Haplotype frequencies were established for 12 Y-chromosome STR loci, including all loci recommended by Scientific Working Group on DNA Analysis Methods Y-STR Subcommittee (DYS391, DYS389I/II, DYS439, DYS393, DYS390, DYS385a/b, DYS438, DYS19 and DYS392) plus DYS437, in the local Chinese population in Hong Kong. In a sample of 481 unrelated males, it was possible to define 424 different haplotypes of which 388 were unique, 26 was found in two individuals, 2 were shared in three individuals, 5 were shared in four individuals and 3 were shared in five individuals. The allele diversity values for each locus ranged from 0.4273 (DYS438) to 0.9555 (DYS385a/b). The observed haplotype diversity value and discrimination capacity were 0.9992 and 0.8815, respectively. In a genetic study of these unrelated males, triple alleles were found at the DYS358 locus in six individuals. The combined Y-chromosome STR polymorphisms provide a powerful discrimination tool for routine forensic applications.     

Analysis of 16 Y STR loci in the Finnish population reveals a local reduction in the diversity of male lineages

We analysed samples of 400 Finnish males using nine Y-chromosomal short tandem repeat (STR) loci (minimal haplotype); for 200 of these subjects an additional seven Y-chromosomal STR loci were used. The geographical distribution of the observed haplotypes was determined from 200 individuals of known paternal origin within Finland. The observed number of alleles varied from 2 to 13 alleles per locus. A total of 146 minimal haplotypes were identified in our population sample. Interestingly, 90 (22.5%) individuals shared an identical haplotype. This haplotype was extremely frequent in the northern and eastern subpopulations of Savo, Pohjanmaa and Karjala (53, 42 and 37%, respectively). With the seven additional loci analysed in the sample of 200 individuals, 120 haplotypes were identified, and individuals sharing the most common haplotype decreased to 13.0%. However, in comparison to other European populations, the Finnish population showed decreased genetic diversity (GD) when the number of different minimal haplotypes in the population was divided by the sample size (36.5% in Finns versus 83.7% on average). Our results strongly support the earlier hypothesis of individual isolated Y-chromosomal lineages and population substructuring in Finland. For paternity testing, power of exclusion was 92% using minimal haplotype data, but including the seven additional loci this value increased to 97%.     

Allele frequencies of 15 STR loci of Luoba ethnic group in Tibet (Southwestern China)

Allele frequency data for 15 short tandem repeat (STR) loci included in the AmpFlSTR Identifiler kit were obtained from a sample of 93 healthy unrelated individuals of Luoba population born in Tibet Autonomy Region of China (Southwestern China). In these samples, 141 alleles and 365 genotypes were observed for 15 STR loci. The distribution of these observed genotypes were not significantly different from the expected distribution according to Hardy-Weinberg equilibrium.     

肿瘤组织中部分杂合性丢失判定标准的适用性评估

目的 对肿瘤组织中部分杂合性丢失(partial loss of heterozygous,pLOH)的判定标准在Identifiler系统中的适用性进行评估.方法 将696例正常无关个体Identifiler数据中共8428个杂合子基因座,对两个体同一杂合子基因座随机配对,构建两等位基因峰高或峰面积比值比.77对肿瘤-正常组织对Identi-filer分型数据中共896对杂合子基因座,将肿瘤组织与其身源正常组织配对构建两等位基因峰高或峰面积比值比.对上述比值比频率分布进行曲线拟合,按比值rt<0.5和>2.0的标准判断正常无关个体对杂合子不均匀扩增误判为pLOH的比例,并比较依据峰高比值比和峰面积比值比对pLOH检出率的差异.结果 正常无关个体对中共4214对杂合子基因座对的比值比和肿瘤-正常组织对中共896对杂合子基因座对的比值比均呈正态分布.按照峰高或峰面积比值比<0.5和>2.0的标准,正常无关个体对中有0.12%误判为pLOH.依据峰高比和依据峰面积比对肿瘤组织中pLOH检出率的差异无统计学意义(P=0.5632).结论 以峰高比值比或峰面积比值比(<0.5或>2.0)作为肿瘤组织中pLOH判断方法和标准适用于Identifiler系统.     

甲醛固定石蜡包埋组织STR分型检测

目的评估10%甲醛固定石蜡包埋组织STR分型结果的影响因素。方法采用QIAGEN法、IQ法、Chelex法对2具新鲜尸体在尸检时常规制备的心、脑、肝、脾、肾、肺、胃、肠石蜡包埋组织进行DNA提取,用AmpFlSTR Identifiler试剂盒进行PCR扩增,在3100-Avant上完成片段分析。另外对15个案例中室温保存1～5年的心、肝、肺、肠存档石蜡包埋组织共56份采用同样的方法进行STR分型。以STR基因座检出率评估分型有效性。结果各种组织DNA片段均随着保存时间延长而持续降解,其中心、肺组织STR基因座检出率与保存时间存在线性相关。相同保存时间时,各种组织基因座检出率差异有统计学意义。其中以肺组织在不同保存时间中基因座检出率最高。结论在甲醛固定时间一定的条件下,存放时间、组织类型、DNA提取方法和PCR模板质量浓度是影响石蜡包埋组织STR分型的重要因素。     

Allele frequencies and population data for 17 Y-chromosome STR loci in a Serbian population sample from Vojvodina province

Seventeen Y-chromosomal STR (short tandem repeat) loci were analyzed in a group of 185 healthy unrelated male individuals (n=185) from the population of Serbian province of Vojvodina. After minimal haplotype STR loci analysis we observed 129 different haplotypes. The most frequent haplotype was found in 13 copies, and total haplotype diversity was 99.11%. After analysis of additional eight Y-STR loci (DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635 and YGATAH4) there were 176 different haplotypes observed, out of which 168 appeared in single copies, and 7 haplotypes appeared twice. The most frequent haplotype was found in three copies. The haplotype diversity (99.94%) and discrimination capacity (95.13%) were calculated. Comparisons were made with previously published haplotype data on neighbouring population samples and significant differences were demonstrated at DYS19, DYS389II and DYS393 loci. Pairwise comparison of populations revealed that our sample was significantly different only from Hungarian sample (RST=23.98%, p=0.0091).     

Analysis of STR polymorphisms in the northeast Chinese population

The distribution of allele frequencies for 12 short tandem repeats (STR) loci were determined in 300 unrelated healthy Chinese individuals living in northeast of China, using AmpFlSTR Profiler Plus kit and AmpFlSTR Green I kit (PE, Applied Biosystems). In these samples, 123 alleles and 399 genotypes were observed for 12 STR loci. The distribution of these observed genotypes were not significantly different from the expected distribution according to Hardy-Weinberg equilibrium.     

Prevalence of Demodex in health personnel working in the autopsy room

The health personnel working in the autopsy rooms and laboratories are considered among the professional groups carrying a high risk of contamination with infection. In this study, we have investigated the prevalence of Demodex, which provides a convenient environment for bacteria and acts as a vector for certain microorganisms, in the health personnel working in autopsy rooms. The study, which was cross-sectional, was conducted on 58 health personnel working in autopsy rooms. A questionnaire was administered to the individuals. Specimens were obtained from 4 different regions of the face using the standard skin-surface biopsy technique. The data obtained were then evaluated statistically. This study group consisted of 76% males and 24% females. The prevalence of Demodex was 26%. Demodex was found to occur more frequently in women. The most frequent occurrence of Demodex was seen among people with darker complexion and in cheek localizations. We believe that Demodex, which has a role in the pathogenesis of dermatologic diseases, provides a convenient environment for bacteria, and acts as a vector for some pathogenic microorganisms, poses a risk as far as individuals working in the autopsy room are concerned.     

Empirical analysis of the STR profiles resulting from conceptual mixtures

Samples containing DNA from two or more individuals can be difficult to interpret. Even ascertaining the number of contributors can be challenging and associated uncertainties can have dramatic effects on the interpretation of testing results. Using an FBI genotypes dataset, containing complete genotype information from the 13 Combined DNA Index System (CODIS) loci for 959 individuals, all possible mixtures of three individuals were exhaustively and empirically computed. Allele sharing between pairs of individuals in the original dataset, a randomized dataset and datasets of generated cousins and siblings was evaluated as were the number of loci that were necessary to reliably deduce the number of contributors present in simulated mixtures of four or less contributors. The relatively small number of alleles detectable at most CODIS loci and the fact that some alleles are likely to be shared between individuals within a population can make the maximum number of different alleles observed at any tested loci an unreliable indicator of the maximum number of contributors to a mixed DNA sample. This analysis does not use other data available from the electropherograms (such as peak height or peak area) to estimate the number of contributors to each mixture. As a result, the study represents a worst case analysis of mixture characterization. Within this dataset, approximately 3% of three-person mixtures would be mischaracterized as two-person mixtures and more than 70% of four-person mixtures would be mischaracterized as two- or three-person mixtures using only the maximum number of alleles observed at any tested locus.     

Allele frequencies for 70 autosomal SNP loci with U.S. Caucasian, African-American, and Hispanic samples

189 samples from 3 different U.S. sample groups Caucasian (74), African American (71) and Hispanic (44) were typed for 70 autosomal genetic markers. These 70 markers are bi-allelic (C/T) short nucleotide polymorphisms (SNPs). For each sample, the 70 SNP markers were typed in 11 unique 6-plexes and a single 4-plex PCR. A total of 10 of the 210 tests (70 loci x 3 populations) for Hardy-Weinberg equilibrium indicated a statistically significant result. In order to evaluate the minimum number of SNP loci needed to distinguish all 189 samples from one another, we ranked the loci according to their levels of observed heterozygosity and p-values obtained upon testing for Hardy-Weinberg equilibrium. The top 12 loci according to these ranking criteria were tabulated along with the number of unique genotypes observed when combining subsequent SNP markers. The 12 selected SNPs possessed an observed heterozygosity of >0.45 in all three populations examined and thus would be expected to exhibit more differences between samples. All of the 189 samples in this study were individualized with a subset of 12 SNP loci. However, it is likely that the addition of more than 12 SNP loci will be required to resolve larger sets of unrelated individuals from one another. By way of comparison, in these same 189 individuals all but one pair is resolved from one another with three of the traditional short tandem repeat (STR) loci possessing the highest heterozygosity values (D2S1338, D18S51, and FGA) run with the Identifiler kit. The final pair of unrelated samples could be resolved with the combination of 4 STR loci: D2S1338, D18S51, FGA, and VWA.