个体识别SNPs位点组合筛选与法医学应用价值初探

目的筛选用于包括中国主要民族在内的多个群体个体识别的SNPs位点组合体系。方法以Kidd实验室筛选的86个SNPs位点、欧洲SNPforID组织构建的52-plex SNPs复合检测体系为基础,收集和整理这些位点在HapMap数据库中11个人群的分型数据,计算各位点杂合度和Fst值,筛选杂合度〉0.4,Fst值〈0.06,并在研究人群中处于Hardy-Weinberg和连锁平衡的位点组合。针对这些位点,采用MassARRAY分子阵列技术对自行收集的8个人群（尼日利亚人、坦桑尼亚查加人、印度人、丹麦人、俄罗斯汉特人、中国汉族、藏族、维吾尔族）308份样本进行分型,统计群体遗传学参数。结果按本文标准共筛选出66个SNPs位点,均符合Hardy-Weinberg平衡,之间互不连锁,平均杂合度和Fst值分别为0.475、0.014。在本文收集的8个人群中的随机匹配概率在1.45E-24~4.72E-27之间,累积非父排除率为0.999 995 608~0.999 997 876之间。结论本文筛选的SNPs组合系统具有较强的个体识别能力,可用于本文调查的HapMap数据库中11个人群和本文收集的8个人群的个体识别鉴定。     

Genome‐wide Screen for Individual Identification SNPs (IISNPs) and the Confirmation of Six of Them in Han Chinese with Pyrosequencing Technology*

Abstract: Single nucleotide polymorphisms (SNPs) offer promise to forensic DNA analysts, but it remains uncertain whether a panel of individual identification SNPs can be as informative as the Combined DNA Index System short tandem repeats. Based on the highly accurate and publicly available HapMap SNP database (r21a) and a minor allele frequency cutoff of ≥0.45, we completed a genome‐wide screen through 3,905,819 SNPs with internally modified computer programs and identified 1439 SNPs with high heterozygosity and low F_st values among four populations (Utah Caucasian, Han Chinese, Tokyo Japanese, and Nigerian Yoruba). Using pyrosequencing technology, we studied six loci in a relatively large group of samples to determine whether these loci were as informative as the HapMap data suggest. These SNPs performed as expected in the Han Chinese in terms of heterozygosity and F_st. The 1439 identified SNPs should provide a comprehensive and reliable set of loci for identity and relationship testing.     

Eye colour single nucleotide polymorphisms (SNPs) variants in Thai population

Human eye colour is recognized as one of the visible characterized features that would be valuable for forensic identification by predicting these phenotypes with particular genotypes. Recent gene association study had figured the remarkable variants mainly in OCA2 and HERC2 genes. In this study, eight human eye colour single nucleotide polymorphisms (SNPs) in five pigmentation genes, OCA2 (rs7495174, rs4778241 and rs4778138), HERC2 (rs12913832 and rs1667394), SLC24A4 (rs12896399), SLC45A2 (rs16891982) and TYR (rs1393350) were investigated in 374 Thai samples. The homozygote genotypes were predominantly observed in rs16891982 (GG/0.9920), rs1393350 (GG/0.9973) and rs12913832 (AA/0.9866). The allele frequency comparison with other populations in HapMap had identified the major allele of East Asia and Thai. Furthermore, the analysis of haplotype block of HERC2-OCA2 comprised five SNPs (rs12913832, rs1667394, rs7495174, rs4778241 and rs4778138) presented the most haplotype was AG-GAG (0.5199), which was rarely observed in European population.     

Parentally imprinted allele (PIA) typing in the differentially methylated region upstream of the human H19 gene

The H19 gene is a paternally imprinted gene located on chromosome 11p15.5. In this study, the H19FR1 and H19FR2 haplotype polymorphisms including four and three SNPs, respectively, upstream of the H19 gene according to the GenBank sequence (accession no. AF125183) were investigated. Five haplotypes and nine genotypes were detected for H19FR1 in the Chinese Han population by means of PCR and subsequent denaturing gradient gel electrophoresis (DGGE). The power of discrimination (Dp), polymorphism information content (PIC) and probability of paternity exclusion (PE) were estimated to be 0.803, 0.58 and 0.322, respectively. For the H19FR2, two haplotypes and three genotyes were observed, and the Dp, PIC and PE were 0.626, 0.37 and 0.162, respectively. Sequencing results showed that only two of the four reported SNPs, a7342g and g7547a, were detected in H19FR1 in the Chinese Han population, and two new SNPs, g7351c and a7357g, were found. In the H19FR2 region, only one of the three reported SNPs, a8097g, was detected. Based on the methylation status of the genomic DNA, selective detection of the parental alleles for H19FRs was examined by using two types of enzymes, the methylation-sensitive restriction enzyme (msRE) HpaII or HhaI and McrBC. Genomic DNA digested by either HpaII or HhaI, revealed a single band derived from the paternal allele, as a result of cleavage of unmethylated recognition sites on the maternal allele. On the contrary, the use of McrBC, which can digest a methylated paternal sequence, resulted in exclusively amplifying the maternal allele. This parentally imprinted allele (PIA) typing method could be one of the useful techniques for discriminating the parental origin of alleles.     

人类D19S40基因座在不同人种中的遗传多态性研究

采用ＰＣＲ技术分析中国汉族、德国人、斯洛伐克人和美国黑人群体Ｄ１９Ｓ４００基因座的遗传多态性及世界三大人种之间的差异。四个群体共调查了６２０人,发现了１１个等位基因,观察到４７种基因型。各群体观察杂合度为：０．７８～０．８８,个人识别机率为：０．９３８５０～０．９６６４。四个群体基因型频率分布符合Ｈａｒｄｙ－Ｗｅｉｎｂｅｒｇ平衡（Ｐ＞０．０５）,三大人种（蒙古人种、高加索人种、美国黑人）之间Ｄ１９Ｓ４００基因座等位基因频率分布存在极显著差异（Ｐ＜０．０１）。结果显示Ｄ１９Ｓ４００基因座在群体遗传学研究和法医学个人识别中有较高应用价值     

Inferring ancestral origin using a single multiplex assay of ancestry-informative marker SNPs

Tests that infer the ancestral origin of a DNA sample have considerable potential in the development of forensic tools that can help to guide crime investigation. We have developed a single-tube 34-plex SNP assay for the assignment of ancestral origin by choosing ancestry-informative markers (AIMs) exhibiting highly contrasting allele frequency distributions between the three major population-groups. To predict ancestral origin from the profiles obtained, a classification algorithm was developed based on maximum likelihood. Sampling of two populations each from African, European and East Asian groups provided training sets for the algorithm and this was tested using the CEPH Human Genome Diversity Panel. We detected negligible theoretical and practical error for assignments to one of the three groups analyzed with consistently high classification probabilities, even when using reduced subsets of SNPs. This study shows that by choosing SNPs exhibiting marked allele frequency differences between population-groups a practical forensic test for assigning the most likely ancestry can be achieved from a single multiplexed assay.     

基于等位基因特异性PCR原理建立的SNP分型新方法

目的建立一种新方法,对多个单核苷酸多态性(singlenucleotidepolymorphism,SNP)位点进行分型。方法基于等位基因特异性PCR原理,采用荧光标记复合扩增和毛细管电泳技术,根据PCR片段长度差异进行分型。选择SNP位点共11个,每个SNP位点设计两条长度不同、3’末端分别与SNP两个等位基因碱基配对的上游引物,同时为了增加特异性,在两条等位基因上游引物的3’末端第3或第4位碱基人为引入错配。在距离上游引物100～300bp范围内的合适位置,设计下游共用引物,并进行荧光标记。所有位点经过复合扩增后,PCR产物经ABIPrismTM310型遗传分析仪电泳分离,确定每个SNP的基因型。结果每个SNP位点纯合子为单一产物峰,杂合子则为长度不同的两个产物峰。不同的SNP位点扩增产物长度不同,根据产物长度和产物峰的数量进行SNP分型,一次完成11个SNP位点分型,其结果与直接测序完全一致。结论荧光标记复合扩增片段长度差异等位基因特异性PCR法是一种简单快速而有效的SNP分型新方法。     

Analysis of genotype frequencies and interlocus association for the PM, DQA1, and D1S80 loci in four populations

Allele frequencies of the LDLR, HBGG, GYPA, D7S8, GC, DQA1, and D1S80 loci are presented and genotypes are analyzed for each of four ethnic groups: African Americans (n = 200), US Caucasians (n = 200), US Hispanics (n = 200), and Japanese (n = 89). Hardy-Weinberg genotypic proportions were observed in all but two of the 28 population-locus tests undertaken. Those two instances are attributable to type I statistical error. Gametic equilibrium among loci is an assumption invoked for application of the product rule to utilize the discriminatory power from two or more loci simultaneously. Two statistical methods, a genotype matching statistic and log-linear modeling, were used to evaluate gametic disequilibrium. The match statistic, comparing observed to expected likelihood of genotypic identity for seven loci among pairs of individuals within the database, revealed only one statistically significant deviation among 20 tests. As expected, the probability of match was generally lowest in the test on all ethnic groups combined, indicating that allele frequencies differ among ethnic groups for some of the loci. This was confirmed with the statistic theta to measure ethnic stratification, in which about 0.10 of the genetic variation is apportioned among the four ethnic groups for four of the structural loci (LDLR, HBGG, GC, and DQA1), while for GYPA, D7S8, and D1S80, variation is more uniformly distributed among ethnic groups. Log-linear modeling was also applied to the five PM loci. The most parsimonious log-linear model included only three higher order terms: the two-way interactions of three of the PM loci with ethnic group. These three instances (LDLR, HBGG, and GC) indicated differences in allele frequencies between ethnic groups. No two or higher way interaction (disequilibrium) was observed among loci. In summary, the assumptions of Hardy-Weinberg and gametic equilibrium that facilitate the use of the five PM loci, DQA1 and D1S80 in forensic applications are consistent with the allele and genotype frequencies observed in these populations.     

Genetic variation of 13 STR loci in the four endogamous tribal populations of Eastern India

We have analysed 13 autosomal STR loci in four endogamous tribal populations from two eastern states (Orissa and Nagaland) of India. The Gadaba, Kuvi Khond and Lotha Naga populations have not been analysed for microsatellite genetic variation previously. The allele frequencies for all loci are within the range observed in the geographical region and racial background, though some alleles showed greater variation. Departures from the Hardy-Weinberg equilibrium were tested by three methods and two loci (THO1 and TPOX) showed significant departures for all measures in Gadaba and Lotha Naga populations. The exclusion probability and discrimination probability were high for all analysed loci in all populations. There is no evidence for association of alleles among the STR loci studied. This allele frequency information will be useful for forensic, paternity and population genetic studies.     

Mass spectrometry-based SNP genotyping as a potential tool for ancestry inference and human identification in Chinese Han and Uygur populations

Ancestry informative SNPs (AISNPs) are genetic variants that exhibit substantially different frequencies between populations from different geographical regions; thus, they can provide some valuable information regarding samples and be used in predicting an individual's ancestry origin. In this study, we selected the potentially best SNPs from our previous study with genome-wide high-density SNP data in mainland Chinese Uygur and Han populations and investigated the allele distribution patterns and genetic information of AISNPs with a mass spectrometry-based SNP genotyping panel. Mass spectrometry-based detection technology offers the opportunity to analyze forensic DNA samples and obtain SNP variants with accuracy and ease. The panel can distinguish and cluster Han and Uygur populations and is suitable for human identification and parentage testing in the two populations. Heatmap, PCA, and Structure analyses indicated that the ideal 64 AISNPs can collectively provide additional information on differences among populations from East Asia, South Asia, Europe and Africa. Additionally, the results proved that the Uygur population is the admixture of East Asia and Europe.     

中国北方汉族人群HLA-DQα基因型及其等位基因频率的分布

应用PCR和等位基因特异性寡该苷酸（ASO）探针杂交技术对中国北方汉族人群的HLA－DQα基因进行分型。在246例无关个体中观察到4种等位基因组成的10种基因型。等位基因频率分布在10．0～31．9％之间。基因型的分布符合Hardy－Weinberg定律。DP值为0．8669。对6个家系49个个体的调查表明，HLA－DQα基因按孟德尔方式遗传。不同人群HLA－DQα的DP值比较，中国人群高于其它人群。     

DNAc: A clustering method for identifying kinship relations between DNA profiles using a novel similarity measure

After decades of refinement, DNA testing methods have become essential tools in forensic sciences. They are essentially based on likelihood ratio test principle, which is utilized specifically, by using as prior knowledge the allele frequencies in the population, to confirm or refute a given kinship hypothesis made on two genotypes. This makes these methods ill suited when allele frequencies or kinship hypotheses are unavailable. In this paper, we introduce DNAc, a new clustering methodology for DNA testing based on a new similarity measure that allows an accurate retrieval of the degree of relatedness among two or more genotypes, without relying on kinship hypotheses or allele frequencies in the population. We used DNAc in analyzing microsatellite DNA sequences distributed among 12 genotypes from normal individuals from two distinct families. The results show that DNAc accurately determines kinship among genotypes and further gathers them in the appropriate kinship groups.     

Multiplex PCR development of Y-chromosomal biallelic polymorphisms for forensic application

Single-nucleotide polymorphisms of Y chromosome (Y-SNPs) are a class of markers of interest in forensic investigations, because many of them show regional specificity, providing useful information about the geographic origin of a subject or evidence under investigation. A first multiplex with 7 SNPs (M35, M89, M9, M170, M172, M45, M173), which occur in the basal branches of the phylogenetic tree and are able to assign a subject to known most frequent European haplogroups, was designed. SNP genotyping was accomplished by hot-start PCR with primers amplifying fragments between 96 and 136 nucleotides, minisequencing, and capillary electrophoresis of extension products. Ninety seven subjects of known geographic provenance were studied, of which 68 from Europe. Of these, 57 had mutations found more frequently in European haplogroups and 11 more frequent in Asian populations. Subjects from non-European countries were also examined and had haplogroups common in their regions of provenance. Experiments with low molecular weight DNA gave positive amplification from 1 ng of DNA for all seven SNPs.     

The Mediterranean basin: A population genetic study based on 25 X-chromosome SNPs

The X-chromosome has valuable characteristics for population genetic studies. In order to investigate the genetics of the human Mediterranean populations further, we developed a 25 X-chromosome SNP-multiplex typing system. The system was based on PCR multiplex amplification and subsequent multiplex single base extension with the SNaPshot reaction, capillary electrophoresis and multicolor fluorescence detection.We investigated 11 Mediterranean populations with the 25 X-chromosome SNPs. A high overall homogeneity was found among the Mediterranean populations except for Moroccans, who differed genetically from the rest of the populations in the Mediterranean area. This result supports the hypothesis of a low incidence of the south-north genetic interchange at the western shores of the Mediterranean basin. A low genetic distance was found between populations in the Middle East and the western part of the Mediterranean area most likely reflecting the strong effect of the Neolithic wave.A certain level of background linkage disequilibrium among the 25 SNPs on the X-chromosome in Ibiza and Cosenza was observed, possibly as a consequence of their demographic history.     

Genetic diversity at two pentanucleotide STR and thirteen tetranucleotide STR loci by multiplex PCR in four predominant population groups of central India

Genetic diversity study at STR loci in 208 individuals belonging to two backward groups, one caste and one tribal community of Central India called "Chhattisgarh" has been carried out to evaluate significance of Powerplex System loci in human identification and population diversity. Populations are Agharia (72), Satmani (50), Dheria Gond (36) and Teli (50). Fifteen loci (Powerplex 16 Kit) studied are Penta E, D18S51, D21S11, THO1, D3S1358, FGA, TPOX, D8S1179, vWA, Amelogenin, Penta D, CSF1PO, D16S539, D7S820, D13S317 and D5S818. The studied penta nucleotide STR (two) and 13 tetranucleotide (CODIS ) STR are found to be highly polymorphic genetic markers in all studied populations. Most common allele for the four studied population has been found to be same at THO1 (allele 9), D8S1179 (allele 14), CSF1PO (allele 12), Penta E (allele 11) and D16S539 (allele 11). Penta E is found to be most polymorphic (PD=0.89373) among studied 15 STR loci in four populations of Central India.     

Analysis of 50 SNPs in CYP2D6, CYP2C19, CYP2C9, CYP3A4 and CYP1A2 by MALDI-TOF mass spectrometry in Chinese Han population

One of the major challenges in the near future is the identification of genes that affect the metabolism of different drugs. Large scale association studies that utilise single nucleotide polymorphisms (SNPs) have been considered a valuable tool for this purpose. CYP2D6, CYP2C19, CYP2C9, CYP3A4 and CYP1A2 were found to be involved in the majority of hepatically cleared drugs. To determine the allele frequencies of some SNPs that may have great potential value in forensic science, we screened 50 SNPs in these 5 CYP genes in Chinese Han people using an accurate, high-throughput, cost-effective method. Primers were designed using the MassARRAY Assay Design software. Genomic DNA was prepared from blood samples obtained from individuals of Chinese Han origin. Multiplex PCR was performed to amplify the relevant gene fragments, and the polymorphisms were analysed by allele-specific primer extension followed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). A panel of genomic DNA samples previously genotyped by other methods were analysed simultaneously for quality control, and the results demonstrated that this assay was 100% accurate. A total of 17 of the analysed SNPs were polymorphic. Of these 17 SNPs, 8 (rs16947, rs28371725, rs1800754, rs4244285, rs4986893, rs12248560, rs3758580, rs2242480) had an allele frequency that was significantly different between this Chinese Han population and Caucasians (p<0.01). In addition, the frequencies of two of these SNPs (rs1800754, rs3758581) in our Chinese Han population differed significantly from the existing Chinese frequency data (p<0.01). The described method thus provides reliable results and enables the genotyping of up to thousands of samples by taking advantage of the high-throughput MALDI-TOF technology. The results herein are now included as a supplement to the P450 database.     

X染色体上高信息量SNP位点及其法医学价值

人类X染色体长154.8Mb,其上密布SNP位点,蕴涵着大量的信息。用于法医学鉴定的X-SNP标记多态性好、突变率低。本研究从Hapmap、NCBI的数据库中筛选了167个高信息量SNP位点,这些位点的等位基因在北京汉族人群中的分布频率均高于0.3,通过高通量、高灵敏度的检测方法可对各个X-SNP位点进行分型验证,通过正确的统计学分析可得到其法医学多态性参数。X-SNP位点具有一些常染色体遗传标记无法比拟的优点,作为常规STR基因座的补充,能用于解决特殊的亲子鉴定案,性别鉴定和混合斑鉴定。     

67个X-SNP位点的分型检测和连锁不平衡检验

目的 筛选一组在中国汉族人群中具有法医学应用前景的X-SNP位点.方法 根据dbSNP和HapMap两个数据库提供的位点信息和频率数据从X染色体上筛选出67个候选X-SNP位点,采用多重PCR联合基质辅助激光解析电离飞行时间质谱技术检测中国汉族人群428名无关个体,获得67个候选X-SNP位点在中国汉族人群中的频率数据...     

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.