SNP genotyping by multiplex amplification and microarrays assay for forensic application

OBJECTIVE: Research on the application feasibility of SNP genotyping for forensic identification by microarrays. METHODS: Oligonucleotide microarrays which could detect 34 different SNPs were used. After hybridization and washing, the arrays were scanned and fluorescence intensities analyzed using Microarray software. Population studies on 34 SNP loci were carried out in a sample of 109 unrelated Chinese Han individuals using oligonucleotide microarrays for genotype detection. The method was also applied to cases. RESULTS: According to the results of population studies, no deviations from Hardy-Weinberg equilibrium could be found. Among the 34 loci, 3 SNPs were low informative, 4 were medium informative and 27 were high informative. The combination discrimination power (CDP) of the 31 optimal polymorphic SNPs was 0.9999999999979. The matching probability was 2.13 x 10(-12). The average exclusion probability in paternity testing for duos was 0.9609. The average exclusion probability in paternity testing for trios was 0.9970. CONCLUSION: The data and case application demonstrated that SNP typing by oligonucleotide probe microarrays was a useful technique for paternity testing and individual identification. Combined with the 28 SNPs loci distributed on HLA-DRB1 and ABO genes, the combination discrimination power (CDP) was 0.9999999999999910. The matching probability was 9.02 x 10(-15). The average exclusion probabilities in duos and in trios were 0.9894 and 0.9992, respectively. It may be concluded that the 59 SNPs loci yield the same power in forensic identification as CODIS STRs currently used.     

31个SNP位点多重PCR扩增和芯片分型技术的建立及其法医学应用

目的对SNP基因分型芯片在个体识别中的应用价值进行研究。方法根据SNP不同等位基因的序列设计探针,制成分型芯片。采用4个复合PCR体系,用末端标记了Cy5的引物进行复合PCR扩增,产物与寡核苷酸探针进行杂交,根据杂交产生的荧光信号值确定样品在各SNP位点的基因型。将这一方法应用于109份样本的分型,根据基因型分布统计分析31个SNP位点的法医学应用价值。同时,进行家系调查和方法灵敏度分析。结果方法的灵敏度为1ng;所检测的31个SNP位点的累积个体识别率为0.9999999999979(偶合率为2.13×10-12),二联体亲子鉴定中累积非父排除率为0.9609,三联体亲子鉴定中累积非父排除率为0.9970。家系调查的结果表明,这些位点等位基因由亲代向子代的传递符合孟德尔遗传定律。结论上述31个SNP位点为中高信息量位点,适用于法医学个体识别,可作为当前STR系统的补充。     

SNPs and MALDI-TOF MS: tools for DNA typing in forensic paternity testing and anthropology

DNA markers used for individual identification in forensic sciences are based on repeat sequences in nuclear DNA and the mitochondrial DNA hypervariable regions 1 and 2. An alternative to these markers is the use of single nucleotide polymorphisms (SNPs). These have a particular advantage in the analysis of degraded or poor samples, which are often all that is available in forensics or anthropology. In order to study the potential of SNP analysis in these fields, 41 SNPs were selected on the basis of following criteria: conservation, lack of phenotypic expression, and frequency of occurrence in populations. Thirty-six autosomal SNPs were used for genotyping 21 inclusionary and 3 exclusionary paternity cases. The behavior of 5 X-chromosome SNPs was analyzed in a French representative population. Our approach to SNP typing is a multiplex PCR based amplification followed by simultaneous detection by primer extension (PEX) analyzed by Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS). The selected autosomal SNPs showed independent inheritance and gave clear results in paternity investigation. All X-SNPs were useful as both paternity and identification markers. PEX and MALDI-TOF MS, with their high sensitivity, precision and speed, gave a powerful method for forensic and anthropological exploitation of biallelic markers.     

Forensic typing of autosomal SNPs with a 29 SNP-multiplex—Results of a collaborative EDNAP exercise

We report the results of an inter-laboratory exercise on typing of autosomal single nucleotide polymorphisms (SNP) for forensic genetic investigations in crime cases. The European DNA Profiling Group (EDNAP), a working group under the International Society for Forensic Genetics (ISFG), organised the exercise. A total of 11 European and one US forensic genetic laboratories tested a subset of a 52 SNP-multiplex PCR kit developed by the SNPforID consortium. The 52 SNP-multiplex kit amplifies 52 DNA fragments with 52 autosomal SNP loci in one multiplex PCR. The 52 SNPs are detected in two separate single base extension (SBE) multiplex reactions with 29 and 23 SNPs, respectively, using SNaPshot kit, capillary electrophoresis and multicolour fluorescence detection. For practical reasons, only the 29 SBE multiplex reaction was carried out by the participating laboratories. A total of 11 bloodstains on FTA cards including a sample of poor quality and a negative control were sent to the laboratories together with the essential reagents for the initial multiplex PCR and the multiplex SBE reaction. The total SNP locus dropout rate was 2.8% and more than 50% of the dropouts were observed with the poor quality sample. The overall rate of discrepant SNP allele assignments was 2.0%. Two laboratories reported 60% of all the discrepancies. Two laboratories reported all 29 SNP alleles in all 10 positive samples correctly. The results of the collaborative exercise were surprisingly good and demonstrate that SNP typing with SBE, capillary electrophoresis and multicolour detection methods can be developed for forensic genetics.     

Internal validation of 29 autosomal SNP multiplex using a ABI 310 genetic analyser

In the last few years genetic identification and paternity testing have begun to make increasing use of autosomal SNP (Single Nucleotide Polymorphism) typing as a supplement or alternative to STR analysis. With the improvement in detection technology SNP analysis is likely to be easier and more sensitive, with the generation of new methods and multiplex systems for a growing array of SNP markers. SNPforID consortium developed 52 SNP PCR multiplex for human identification purposes detected with 23 plex and 29 plex single base extension reactions (Auto1 and 2 respectively). In this study, internal validation for the 29 SNPs of Auto2 was carried out by performing a 29 plex PCR and single base extension reaction on control samples and previously analyzed forensic casework and subsequent detection with an AB 310 Genetic Analyzer. We tested the accuracy, precision, sensitivity and reproducibility of the Auto2 multiplex with this instrument in our laboratory. We used 9947A control DNA samples of the AmpF?STR Identifiler™ kit to test the validation parameters together with non-probative DNA samples from whole blood and buccal swab samples of 29 healthy donors from different parts of Istanbul. Good results were obtained but interpretation of the peak patterns obtained on the AB 310 requires care and thorough optimization before they can be readily compard to those obtained from multiple capillary AB 31xx Analyzers. We succesfully optimized and validated the SNPforID Auto2 multiplex system for identification analyses in our laboratory.     

Selection of twenty-four highly informative SNP markers for human identification and paternity analysis in Koreans

A number of DNA marker types suitable for human identification and parentage testing have been developed, of which single nucleotide polymorphisms (SNPs) merit attention as they are abundant, genetically stable, and amenable to high-throughput automated analysis. In this regard, 24 highly informative SNP markers representing each 22 autosome and both sex chromosomes were selected, and the allele and genotype frequencies of these SNPs were determined in a group composed of 30 unrelated Koreans. Based on frequency data from this group, the estimated probability of identity (P(I)) and probability of paternity exclusion (P(E)) with 22 autosomal SNP loci were 1.905x10(-10) and 98.9%, respectively. The SNPs in this study offer a small but highly accurate database that will be an essential reference for SNP-based forensic application in the future.     

荧光复合扩增检测3个Y—STR基因座单倍型

目的建立检测3个Y-STR基因座Y-GATA-A7.1、DYS456和DYS443的荧光复合扩增体系,并获取中国汉族人群单倍型频率分布。方法用荧光标记引物对郑州地区203名汉族男性无关个体进行3个基因座复合扩增,ABI3100型遗传分析仪检测、分型。结果Y-GATA-A7.1、DYS456和DYS443基因座分别检出5、6和6个等位基因,其基因多样性(GD值)分别为0.6692、0.5839和0.7053。三个基因座构成的单倍型共有44种,单倍型多样性(HD值)为0.9523。结论建立的3个Y-STR基因座荧光标记复合扩增系统具有很高的识别能力,可应用于法医学实践。     

A 21‐Locus Autosomal SNP Multiplex and its Application in Forensic Science

To develop a cost‐effective technique for single‐nucleotide polymorphism (SNP) genotyping and improve the efficiency to analyze degraded DNA, we have established a novel multiplex system including 21‐locus autosomal SNPs and amelogenin locus, which was based on allele‐specific amplification (ASA) and universal reporter primers (URP). The target amplicons for each of the 21 SNPs arranged from 63 base pair (bp) to 192 bp. The system was tested in 539 samples from three ethnic groups (Han, Mongolian, and Zhuang population) in China, and the total power of discrimination (TPD) and cumulative probability of exclusion (CPE) were more than 0.99999999 and 0.98, respectively. The system was further validated with forensic samples and full profiles could be achieved from degraded DNA and 63 case‐type samples. In summary, the multiplex system offers an effective technique for individual identification of forensic samples and is much more efficient in the analysis of degraded DNA compared with standard STR typing.     

Y-STR基因座应用于刑事案件的独特作用

目的探讨Y-STR基因座在刑事案件中的应用价值。方法采用Y-STR荧光标记复合扩增技术,结合案例应用。结果Y-STR基因座对于涉及男女混合、多名男性混合样本、性别鉴定、父权鉴定等案例中具有特有应用价值。结论Y-STR基因座可应用于法庭科学中的个体识别与同一认定,但在应用中要注意各种特例的发生。     

D18S51及其侧翼区3个SNP组成的SNP-STR在亲子鉴定中的应用

目的将一个单倍型区块内的遗传标记单核苷酸多态性(SNP)和短串联重复序列(STR)组成SNPSTR单倍型,调查其在成都汉族人群中的分布,并探讨其在特殊亲子鉴定案例中的应用价值。方法选取DNA联合索引系统(combined DNA index system,CODIS)中突变率较高的基因座D18S51,与其侧翼区的3个SNP位点(rs8089331、rs8094489、rs7236090)组成SNP-STR,通过巢式等位基因特异性PCR的方法获得SNP-STR单倍型,调查该单倍型在75名成都汉族人群中的分布,并应用于两例D18S51基因座不符合遗传规律的二联体亲子鉴定案件。结果成功建立SNP-STR分型方法,在成都汉族人群中共发现43种单倍型,多态性为0.948 6,并成功解决了两例二联体亲子鉴定案件。结论 SNP-STR具有良好的多态性,有望应用于特殊的亲缘关系鉴定。     

ABO genotyping by duplex amplification and oligonucleotide arrays assay

Objective

Research on the application feasibility of ABO genotyping for forensic identification by oligonucleotide arrays assay.

Methods

Oligonucleotide microarrays which detect three different SNPs in exon 6 and exon 7 for ABO genotyping were used. After hybridization wash, the arrays were scanned and fluorescence intensities were analyzed using microarray population studies on ABO was carried out in a sample of 115 unrelated Chinese Han individuals oligonucleotide arrays for genotype detection. The method was also applied to cases.

Results

Technique could identify six genotypes of ABO system and the results of GeneChip analyses confirmed by PCR–RFLP. According to the results of population studies, no significant deviations Hardy–Weinberg equilibrium could be found. The observed heterozygosity (H-obs) was 0.591. Expected heterozygosity (H-exp) was 0.616. The polymorphic information content (PIC) was the average exclusion probability in paternity testing for duos (PE (1)) was 0.188. The average exclusion probability in paternity testing for trios (PE(2)) was 0.344. The discrimination power 0.777.

Conclusion

The data and case application demonstrated that ABO typing by oligonucleotide probe arrays was a useful technique for paternity testing and individual identification.     

运用二重PCR和DNA芯片技术检测ABO基因型

目的以玻片为载体,用寡核苷酸探针杂交技术检测ABO基因型。方法根据ABO基因座外显子6和外显子7的3个SNP点的序列分布特征设计4条寡核苷酸探针,制成分型芯片。将待测样品DNA用末端标记了Cy5的引物进行二重PCR扩增,产物与芯片上的探针进行杂交,根据杂交产生的荧光信号确定样品的ABO基因型。结果利用ABO芯片,可对血斑、毛发等微量检材进行ABO基因型检测。对115名汉族无关个体的调查表明,ABO基因型的分布符合Hardy-Weinberg平衡,等位基因杂合度观察值和期望值分别为0.591、0.616,多态信息含量为0.544,二联体和三联体非父排除率分别为0.188、0.334,个体识别能力为0.777。结论通过DNA芯片检测ABO基因型的技术适用于法医学样本,可满足高通量的检测需求。     

SNPs in forensic genetics: a review on SNP typing methodologies

There is an increasing interest in single nucleotide polymorphism (SNP) typing in the forensic field, not only for the usefulness of SNPs for defining Y chromosome or mtDNA haplogroups or for analyzing the geographical origin of samples, but also for the potential applications of autosomal SNPs. The interest of forensic researchers in autosomal SNPs has been attracted due to the potential advantages in paternity testing because of the low mutation rates and specially in the analysis of degraded samples by use of short amplicons. New SNP genotyping methods, chemistries and platforms are continuously being developed and it is often difficult to be keeping up to date and to decide on the best technology options available. This review offers to the reader a state of the art of SNP genotyping technologies with the advantages and disadvantages of the different chemistries and platforms for different forensic requirements.     

MtSNP typing before mtDNA sequencing: Why do it?

Analysis of control mitochondrial DNA (mtDNA) hypervariable regions is sometimes the only available method to study hair evidence in forensic casework although being a laborious technique. Nowadays there is a huge interest in new genetic markers such as single nucleotide polymorphisms (SNPs) to type degraded forensic samples. For that purpose, a 10-Plex mitochondrial SNP for haplogroup typing, chosen from several SNP studies and useful to study the most common populations in our laboratory was applied in forensic casework. Hair shafts from three forensic cases with different ethnic backgrounds were studied with mtDNA sequencing and compared with mitochondrial SNPs (mtSNPs) study. Coding mtSNP typing prior to sequencing can allow for a rapid screening in forensic casework, which is emphasized in the first two cases. Moreover, in cases in which mtDNA sequencing fails, mtSNPs can still be detected. This 10 SNP loci multiplex provides a less expensive and simpler method for mitochondrial typing compared to control region mtDNA sequencing, especially when used as a fast screening method.     

Identifiler体系在单亲血缘关系鉴定中应用价值的研究

目的　研究 16基因位点Identifiler体系在单亲血缘关系法医鉴定中的应用价值。　方法　对无关个体中随机抽样组成的假设父—子二联体 10 0例、正常人群中已知真父—子二联体 10 0例及已知非父—子二联体 10 0例、实际单亲血缘关系亲子鉴定案 2 2 8例、特意省去母亲的二联体鉴定案 136例 ,应用Identifiler体系的 16基因位点进行检测 ,得出每案例的RCP值 ,将检测结果同应用其他体系检测的结果比对 ,同三联体检测结果比对 ,同真实情况比对 ,计算出单独使用Identifiler体系在单亲血缘关系法医鉴定中的正确率。　结果　对 2 2 8例单亲鉴定案应用Identifiler体系检测的结果 ,同应用ProfilerPlus和Cofiler两个体系再加用 2 4个其他位点银染检测 (共 37个位点 )的结果完全相同 ;对无关个体 10 0例及真父—子二联体 10 0例及非父—子二联体 10 0例 ,用Identifiler体系检测的结果同调查核实的真实情况完全相符 ;对 136例特意省去母亲的二联体案 ,用Identifiler体系检测的结果同原实际检案中三联体检测的结果完全相同。　结论　单独使用Identifiler体系完全可以解决法医亲子鉴定中的单亲血缘关系鉴定问题。     

Combination of DNA-based and conventional methods to detect human leukocyte antigen polymorphism and its use for paternity testing

In cases of disputed paternity, the scientific goal is to promote either the exclusion of a falsely accused man or the affiliation of the alleged father. Until now, in addition to anthropologic characteristics, the determination of genetic markers included human leukocyte antigen gene variants; erythrocyte antigens and serum proteins were used for that reason. Recombinant DNA techniques provided a new set of highly variable genetic markers based on DNA nucleotide sequence polymorphism. From the practical standpoint, the application of these techniques to paternity testing provides greater versatility than do conventional genetic marker systems. The use of methods to detect the polymorphism of human leukocyte antigen loci significantly increases the chance of validation of ambiguous results in paternity testing. The outcome of 2384 paternity cases investigated by serologic and/or DNA-based human leukocyte antigen typing was statistically analyzed. Different cases solved by DNA typing are presented involving cases with one or two accused men, exclusions and nonexclusions, and tests of the paternity of a deceased man. The results provide evidence for the advantage of the combined application of various techniques in forensic diagnostics and emphasizes the outstanding possibilities of DNA-based assays. Representative examples demonstrate the strength of combined techniques in paternity testing.     

Mutations at 17 STR loci in Chinese population

Knowledge about mutation rates and the mutational process of short-tandem-repeat (STR) or microsatellite loci used in forensic analysis is crucial for the correct interpretation of resulting genetic profiles. We analysed a total of 19,754 samples from 6532 paternity testing cases at 17 STR loci which are commonly applied to forensics. The parenthood in each of these cases was highly validated (probability>99.99%). We identified 178 mutations. Locus-specific mutation rate estimates varied between 7.0 x 10(-5) and 2.2 x 10(-3), and the overall average mutation rate estimate was 8.4 x 10(-4). The observed mutational features for STRs have important consequences for forensic application such as the definition of criterions for exclusion in paternity testing and the interpretation of DNA profiles in identification analysis. In order to enrich the reference data of STRs mutations which are valuable for forensic application, we suggest the establishment of such database and ask the whole forensic community for data contribution including China.     

胆囊收缩素基因单核苷酸多态性与精神状态的关系及法医学意义

胆囊收缩素（cholecystokinin,CCK）是一种具有广泛生物学活性的脑肠肽,既是胃肠道主要调节激素之一,还广泛存在于中枢及外周神经系统中以神经递质或神经调质的形式发挥重要的生理作用。近年来国内外研究发现,CCK基因上存在多个单核苷酸多态性（single nucleotide polymorphisms。SNP）位点,其中一45C／T,-196G／A变异与多种精神状态如精神分裂症、抑郁症、自杀行为、帕金森病等存在一定的相关性。这些SNP多态性可应用于法医物证学的亲子鉴定和个人识别,并且可能成为某些特殊案例如涉及精神病鉴定、法医病理学的疾病鉴定、异常行为（自杀倾向等）鉴定的辅助指标之一。     

MiniFiler及Yfiler试剂盒无创产前亲子鉴定的可能性探究

目的采用Mini Filer~(TM)及YFiler~(TM)试剂盒对孕妇血浆进行STR分型,评估上述试剂盒进行无创产前亲子鉴定的可行性。方法采用Mini Filer~(TM)及YFiler~(TM)试剂盒,对2例成人男性的全血及血浆进行STR分型,评估血浆检材的分型准确率及适用性;对8组已知亲子关系的孕妇家系(4组非父,4组亲父,均为男胎样本)采用Mini Filer~(TM)及YFiler~(TM)试剂盒进行STR分型,对STR分型图谱直接观察,总结归纳孕妇血浆STR图谱的特征,探讨进行无创产前亲子鉴定的可行性。结果血浆检材的STR分型结果与全血STR分型结果 100%一致,且等位基因峰高接近,表明血浆是一类可以进行STR分型的检材;观察8组孕妇血浆检材的STR分型图谱,可获得2~5个可用(含胎儿STR信息)Mini-STR位点,1~8个可用Y-STR位点,且在位点充足的情况下(6个),肯定父权家系可计算累计父权指数达192 653,否定父权家系中有3~7个位点支持否定父权。结论采用Mini Filer~(TM)及Yfiler~(TM)试剂盒对孕妇血浆进行STR分型,存在进行无创产前亲子鉴定的可能性。