DHPLC-mtDNA控制区多态性分析系统的建立

目的基于变性高效液相色谱技术,建立一种不需测序和杂交的新的mtDNA控制区多态性分析系统。方法mtDNA控制区序列(包括HVⅠ,HVⅡ和HVⅢ)被分为4个扩增片段,采用配对分析突变检测模式进行DHPLC分析。对DHPLC检测条件(包括柱温和洗脱梯度等)进行优化。对100个不同类型差异序列的组合配对以检验该方法的检测效力。结果10组序列相同的样本配对DHPLC图谱均只显示1个样品峰。对序列相差1个碱基～7个碱基、插入(/缺失)1个碱基、插入(/缺失)2个碱基等类型的90个扩增片段组合,用DHPLC进行分析,均得到≥2个样本峰的DHPLC图谱,序列差异检出率达100%。该技术可检测的异质性DNA成分的最小百分含量为10%。结论DHPLC-mtDNA控制区多态性分析系统快速、经济和实用,在检测mtDNA异质性方面较直接测序更灵敏。     

mtDNA异质性在法医检验中的应用价值

<正> 在一个个体内,各种组织器官及其同一组织的各个线粒体DNA(mitochondrial DNA,mtDNA)序列一致。如果一个个体表现为2种以上的mtDNA序列,则称为该个体mtDNA存在异质性(heteroplas—my)[1,2]。Gill在对疑为俄国沙皇尼古拉二世的遗骸进行mtDNA序列分析时,检测了740个碱基,在16169处发现mtDNA异质性;对其兄弟遗骸测序,     

汉人不同区段头发的线粒体HVII异质性的序列分析

目的探讨汉族人不同区段头发线粒体DNA(mtDNA)HVII区的异质性。方法用5%Chelex100法提取7名汉族个体额、顶、枕及左、右颞部等5个不同部位的不同根不同段的头发mtDNA,同时取各自毛囊作为对照;以两步法扩增纯化后测序反应,3100型遗传分析仪检测。结果不同毛干区段的点异质性多发生于女性长发远段、儿童及老年人,不同区及同一根不同段均可发生点异质性,可多达4处,点异质性可能相同,可能不同,但一般多发生于相同个体毛囊mtDNA点突变处。不同区头发长度异质性不同,同一根头发不同段长度异质性相同。mtDNA点异质性有一定遗传倾向。稀释及混合样本mtDNA图谱也可表现为“点异质性”图谱。结论根据人头发毛干mtDNA测序结果得出“排除”结论时一定应慎重。     

基于Ion Torrent PGM~(TM)测序系统的人mtDNA全测序分析

目的应用Ion Torrent PGM~(TM)测序系统对人线粒体DNA(mitochondria DNA,mtDNA)全序列进行分析检测,研究不同组织间mt DNA序列差异情况。方法通过法医尸体检验采集6名无关个体的组织样本,包括胸腔血液、头发、肋软骨、指甲、骨骼肌和口腔上皮。使用4对引物对线粒体全序列进行扩增,应用Ion Shear~(TM)Plus Reagents试剂盒和Ion Plus Fragment Library试剂盒等构建文库,并在Ion Torrent PGM~(TM)测序系统上进行线粒体基因组全序列测序,并针对异质性位点和在HVⅠ区域突变位点,进行Sanger测序验证。结果所有样本的全基因组mtDNA都扩增成功,6名无关个体分属于6种不同的单倍型,同一个体不同组织之间mtDNA存在异质性差异。异质性位点和HVⅠ区域突变位点采用Sanger测序结果均得到验证。通过Kappa统计方法进行一致性检验后发现,相同个体不同组织的mtDNA序列检验结果仍具有较好的一致性。结论本研究所采用的人线粒体基因组全序列的测序检验方法,可以检测出同一个体不同组织间mtDNA的异质性差异,该差异具有较高的一致性,该结果对mtDNA在法庭科学中的应用具有指导作用。     

DHPLC检测人体线粒体DNA异质性研究

目的建立筛选线粒体DNA异质性的DHPLC方法;检测线粒体DNA高变区的异质性频率。方法选取尸体18例,分别提取血、心、肝、脾、肺、肾、胰腺、脑、肌肉、皮肤、肋骨、指甲及毛发的mtDNA,用DHPLC筛选异质型样本,并用直接测序法进行验证。结果9例个体存在异质性,肌肉组织出现的异质性频率最高。结论正确认识线粒体DNA异质性对于法医学应用领域具有指导意义。     

PCR结合变性梯度凝胶电泳法检测人血mtDNA HVⅡ

目的建立简单、有效的mtDNA单倍型检测及异质性筛查技术,并获取其相应的汉族人群频率分布。方法用PCR结合变性梯度凝胶电泳(DGGE)技术对200例武汉汉族无关个体外周血mtDNA HVⅡ29～290nt区域进行分型检测。结果200例汉族无关个体中,检出17种单倍型,其单倍型多样性(HD值)为0.8826;有4名个体观察到异质性,其发生率为2%。结论PCR-DGGE是一种简单、灵敏、高效的mtDNA多态性及异质性检测技术,可应用于法医学实践。     

中国汉族人群的线粒体DNA控制区多态性研究

探讨mtDNA多态性在法庭科学中个体识别的理论基础。应用PCR扩增产物直接测序方法 ,对 111名中国北方地区汉族人群无血缘关系个体的mtDNA控制区 (HVⅠ和HVⅡ )进行测序分析。在高变区Ⅰ 15 998～ 16 40 0之间发现 10 2处碱基变异 ,10 3个mtDNA单倍型 ;在高变区Ⅱ 0 0 0 35～ 0 0 36 9之间的发现 36处碱基变异 ,6 9个mtDNA单倍型。其可变碱基的变异形式主要为碱基替代 (转换和颠换 )、插入和缺失 ;碱基转换 (78 9% )明显高于颠换(14 3% )、插入 (3 4% ) ,缺失 (3 4% )。分析表明 ,人群个体mtDNA控制区碱基序列 ,基因多样性为 99 9% ,两个无关个体的偶合概率为 0 92 % ,具有高度序列的多态性     

线粒体DNA编码区的多态性

目的研究线粒体DNA(mtDNA)编码区单核苷酸多态性,建立mtDNA编码区多态性在法庭科学中应用的理论基础。方法针对mtDNA编码区nt8162-8483以及nt13070-13299两段序列设计引物,应用直接测序技术研究其多态性。结果两对引物扩增片段长分别为322bp和230bp,共检测到21种变异,24种单倍型,基因多样性为0.7511,两个无关个体的偶合概率为0.2564。结论线粒体DNA编码区多态性位点作为线粒体DNA控制区多态性位点的补充,联合应用可以提高线粒体DNA在法医学应用中的个体识别能力。     

mtDNA—HVⅠ和细胞色素b片段的复合扩增及其法医学应用

目的探讨复合扩增mtDNA D环HV I和细胞色素b片段进行种属鉴定和个体识别的方法及mtDNA-HV I多态性。方法用两对引物同步扩增HV I片段与细胞色素b片段,银染显带检测扩增产物,ABI377测序仪及荧光测序技术分析扩增产物序列多态性。结果人类有279bp,358bp两条带,动物只有358bp一条带。通过对131例随机广东汉族人群个体进行mtDNA控制区(15997～16236))序列测定统计,得出此区域的序列多态性。共发现69个位点变异,平均每个个体存在2.679个碱基突变,检出67个单倍型,基因多样性为97.92％。结论mtDNA控制区(15997—16236)具有较高的序列多态性。为良好的个体识别标记。复合扩增mtDNA D环HV I与细胞色素b片段进行测序分析可以同步进行种属鉴定和个体识别。     

人类mtDNA控制区异质性

目的观察mtDNA的点突变异质性和长度异质性。方法运用直接测序法对50名无关个体及16名母系家族成员的血液、口腔上皮细胞、头发的mtDNAHVI、HVII区序列进行分析,并对20例HVI区直接测序失败的无关个体进行克隆后测序分析。结果同一个体的三种检材样本及16名母系家族成员的序列一致,未见异质性存在;同一个体的不同克隆的C延伸区的长度有差异,存在长度异质性。但同一个体的血液和头发具有相似的长度变异类型,即长度异质性在组织间无差异。结论mtDNA碱基序列具有同质性及稳定性,适用于法医学检案。     

用PCR和ESI-TOF-MS技术检测线粒体DNA的异质性

目的用PCR和ESI-TOF-MS分型技术检测线粒体DNA（mtDNA）D环高变区,通过碱基组成分析mtDNA的异质性。方法从华东汉族群体选取12名无关个体,用PLEX-ID平台进行mtDNA分型。该平台使用12对引物,对mtDNA高变区1（HVⅠ,引物所跨区域为15893~16451）进行碱基组成分析;使用另外12对引物,对mtDNA高变区2（HVⅡ,引物所跨区域为5~603）进行碱基组成分析,考察mtDNA异质性频率。结果 mtDNA多态性区域的碱基组成信息反映出区段内有无异质性。在高变区Ⅰ的12个区段中,有3个区段表现出多聚C长度异质性：在mtDNA高变区Ⅱ（31~576）的12个区段中,有3个区段检见点异质性,另外5个区域检见Poly C长度异质性。结论群体调查表明,mtDNA的序列异质性多见于高变区Ⅱ的103~267区段,多聚C长度异质性多见于高变区Ⅰ的16124~16201、16157~16201、16182~16250区段和高变区Ⅱ的234~367、431~576区段。将mtDNA标记用于母系关系检验和（或）个体识别时,需要格外留意这些异质性信息,以免结论错误。     

Comparative Analysis of the HV1 and HV2 Regions of Human Mitochondrial DNA by Denaturing High-Performance Liquid Chromatography

Abstract:  Denaturing high-performance liquid chromatography (DHPLC) was evaluated as a sequencing-independent means of detecting the presence of sequence differences in pair-wise mixtures of nonconcordant amplicons of human mitochondrial DNA (mtDNA). A total of 920 pair-wise combinations of HV1 and HV2 mtDNA amplicons from 95 individuals were assayed by DHPLC for sequence concordance/nonconcordance. For the 72 combinations of amplicons from different individuals who shared identical DNA sequences, DHPLC assays consistently indicated sequence concordance between the samples. This was in 100% agreement with sequencing data. For the 849 combinations of amplicons which differed in sequence, DHPLC detected the presence of sequence nonconcordance in all but 13 assays to yield 98.5% concordance with sequencing. Thus, DHPLC can be used to detect a diversity of sequence differences (transitions, transversions, insertions, and deletions) in the mtDNA D-loop. Accordingly, DHPLC may have utility as a presumptive indicator of mtDNA sequence concordance samples, as a screen for heteroplasmy/situational mixtures, and as a means for the physical fractionation of the individual contributors to an mtDNA mixture prior to sequencing.     

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.     

Mitochondrial DNA heteroplasmy among hairs from single individuals

A denaturing gradient gel electrophoresis (DGGE) assay was used to detect mitochondrial DNA (mtDNA) sequence heteroplasmy in 160 hairs from each of three individuals. The HV1 and HV2 heteroplasmic positions were then identified by sequencing. In several hairs, the heteroplasmic position was not evident by sequencing and dHPLC separation of the homoduplex/heteroduplex species was carried out with subsequent reamplification and sequencing to identify the site. The overall detection frequency of sequence heteroplasmy in these hairs was 5.8% (28/480) with DGGE and 4.4% (21/280) with sequencing. Sequence heteroplasmy of hair was observed even when the reference blood sample of the individual was homoplasmic. The heteroplasmic positions were not necessarily observed at sites where high rates of substitution have been reported. In two hairs, a complete single base change from the reference blood sample was observed with sequencing, while the heteroplasmic condition at that site in the hair was observed using DGGE. The DGGE results in such samples would serve as an aid in considering the possibility of match significance. In a forensic case, this situation would lead to the possibility of a failure to exclude rather than to be inconclusive.     

Detection and quantification of the age-related point mutation A189G in the human mitochondrial DNA

Mutation analysis in the mitochondrial DNA (mtDNA) control region is widely used in population genetic studies as well as in forensic medicine. Among the difficulties linked to the mtDNA analysis, one can find the detection of heteroplasmy, which can be inherited or somatic. Recently, age-related point mutation A189G was described in mtDNA and shown to accumulate with age in muscles. We carried out the detection of this 189 heteroplasmic point mutation using three technologies: automated DNA sequencing, Southern blot hybridization using a digoxigenin-labeled oligonucleotide probe, and peptide nucleic acid (PNA)/real-time PCR combined method on different biological samples. Our results give additional information on the increase in mutation frequency with age in muscle tissue and revealed that the PNA/real-time PCR is a largely more sensitive method than DNA sequencing for heteroplasmy detection. These investigations could be of interest in the detection and interpretation of mtDNA heteroplasmy in anthropological and forensic studies.     

人类线粒体DNA的异质型

研究中国人群中线粒体 D 环区不同组织间的差别,用 PCR-测序方法对53个无关个体的毛发与血液样本进行线粒体 DNA 高变区 HVⅠ进行测序分析,通过377测序仪检测,发现1例个体中血液与毛发样本线粒体 HV Ⅰ区15997～16401间存在序列差异。在16235碱基处,毛发样本表现为 T,血液样本为 C/T。结果显示中国人群同一个体不同组织存在线粒体序列差异。     

Typing the 1.1 kb control region of human mitochondrial DNA in Japanese individuals

This study presents a reliable method that uses high-fidelity long-range PCR and optimized primers to assess polymorphism and to genotype human mitochondrial DNA (mtDNA). This method was used to analyze polymorphic sites in the human mtDNA control region, including hypervariable regions I, II, and III (HVI, HVII, and HVIII), from 124 unrelated Japanese individuals. In HVI, HVII, and HVIII, 80, 37, and 14 polymorphic sites were identified, respectively, excluding those in the homopolymeric cytosine stretch (C-stretch) regions. The region between HVI and HVII also contained 15 polymorphic sites. On the other hand, C-stretch length heteroplasmy in HVI or HVII was observed in 66 of 124 Japanese individuals (53%), which is much higher than in Caucasian populations. The variants in the C-stretch regions were characterized by counting the number of heteroplasmic peaks split from the single peak in homoplasmic sequences (i.e., 16244G and 16255G in HVI and 285G in HVII). Including the C-stretch length heteroplasmy, the 124 Japanese mtDNA samples were classified into 116 distinct haplotypes. The random match probability and the genetic diversity were estimated to be 0.95% and 0.998581, respectively, indicating that the method presented here has higher discrimination than the conventional method for mtDNA typing using HVI and HVII. [Correction added after publication 30 January 2007: in the preceding sentence random match probability and genetic diversity estimates were corrected from 0.95 and 0.998581%, respectively, to 0.95% and 0.998581, respectively.] The haplogroups and their frequencies observed in this study (i.e., D4; 13.7%, M7a1; 11.3%, D4a; 9.7% and M7b2; 8.9%) were similar to those observed in other studies of Japanese mtDNA polymorphism. The method described here is suitable for forensic applications, as shown by successful analysis of tissues from highly putrefied remains of an infant, which allowed maternal relationship to be determined via mtDNA haplotyping.