东南亚缺失型α地中海贫血的聚合酶链反应快速诊断技术及 …

目的 针对东南亚缺失型α地中海贫血建立一种快速,简便的聚合酶链反应（ＰＣＲ）基因诊断技术,并初步应用于高危胎儿的产前诊断。方法 采用跨越断裂点的ＰＣＲ设计方案,其中一对引物用于扩增－－＾ＳＥＡ缺失基因,另一对引物设计在－－＾ＳＥＡ,－α＾３．７,－α＾４．２的公共缺失区域,用于扩增正常的α珠蛋白基因,两对引物在单管中反应。     

应用PCR－ASO方法对广东地区非缺失型HbH病的检测

为筛查广东地区ＨｂＨ病的基因型，用两对引物多聚酶链反应（ＰＣＲ）选择性扩增α２珠蛋白基因外显子Ⅲ３１８ｂｐＤＮＡ片段和３２７ｂｐＤＮＡ片段，从７２例广东籍，经血液学确诊为ＨｂＨ病的ＤＮＡ标本中筛查出非缺失型ＨｂＨ病１０例，占ＨｂＨ病的１３．９％；缺失型ＨｂＨ病６２例，占ＨｂＨ病的８６．１％。非缺失型ＨｂＨ病α２珠蛋白基因外显子Ⅲ３１８ｂｐＰＣＲ产物，用两对寡核苷酸探针（ＨｂＣＳ－正常和Ｈｂ广西－正常）进行斑点杂交，检出ＨｂＣＳ８例，Ｈｂ广西２例。提示广东地区ＨｂＨ病以基因缺失型为主，非缺失型ＨｂＨ病基因突变大多发生在α２基因     

一个同时具有β和α珠蛋白基因异常家系的分子诊断

为对一个同时具有β和α珠蛋白基因变异家系中的成员进行分子诊断，应用Ｓｏｕｔｈｅｒｎ印迹杂交、多重等位基因特异ＰＣＲ（ＭＡＳ－ＰＣＲ）和双链ＤＮＡ循环测序法等基因分析技术。结果表明：具有中间型β地中海贫血表现型的先证者的基因型为βＩＶＳ－Ⅱ－６５４（Ｃ→Ｔ）杂合子复合αααａｎｔｉ４．２／αα；其父亲为典型的βＩＶＳ－Ⅱ－６５４（Ｃ→Ｔ）杂合子；而母亲的α珠蛋白基因型为αααａｎｔｉ４．２／α－３．７。肽链体外生物合成速率测定结果提示先证者的β珠蛋白肽链的合成速率明显降低（α／β＝２．６３），表明α珠蛋白基因组织的三体型与β地中海贫血杂合子复合存在是导致中间型β地中海贫血的重要分子基础。     

应用PCR—ASO方法对广东地区非缺失型Hb H病的检测

为筛查广东地区Ｈｂ Ｈ病的基因型，用两对引物多聚酶链反应（ＰＣＲ）选择性扩增α２球蛋白基因外显子Ⅲ３１８ｂｐＤＮＡ片段和３２７ｂｐＤＮＡ片段，从７２例广东籍，经血液学确诊为Ｈｂ Ｈ病的ＤＮＡ标本中筛查出非缺失型Ｈｂ Ｈ病１０例，占Ｈｂ Ｈ病的１３．９％；缺失型Ｈｂ Ｈ病６２例，占Ｈｂ Ｈ病的８６．１％。非缺失型Ｈｂ Ｈ病α２珠蛋白基因外显子Ⅲ３１８ｂｐ ＰＣＲ产物，用两对寡核苷酸探针（Ｈｂ ＣＳ－     

不同片段的Dig－HBV－DNA探针在检测血清HBV－DNA的比较

本文运用分子克隆技术、随机引物法用非放射性Ｄｉｇｏｘｉｇｅｎｉｎ标记制备ｐＢＲ３２２－ＨＢＶ－ＤＮＡ全基因探针（７．５ｋｂ）、单纯ＨＢＶ－ＤＮＡ全基因探针（３．２ｋｂ）及经ＢｇＬⅡ限制性内切酶切割后片段ＨＢＶ－ＤＮＡ探针（２．４ｋｂ）。通过检测１３０份血清ＨＢＶ－ＤＮＡ，比较三种探针的敏感度和特异性。     

同时检测三种Myc基因的聚合酶链反应技术

目的建立同时检测Ｍｙｃ基因３个成员Ｌｍｙｃ、Ｎｍｙｃ及Ｃｍｙｃ异常扩增的简便方法。方法采用聚合酶链反应（ＰＣＲ）技术，用一对引物同时扩增Ｍｙｃ基因３个成员第２外显子中的高度保守区，扩增产物经非变性聚丙烯酰胺凝胶电泳及激光扫描。结果此法可以检测Ｍｙｃ基因家族中３个成员的扩增情况。经检测，正常组织细胞没有Ｍｙｃ基因扩增，３２例喉癌组织中４７％有Ｌｍｙｃ和Ｃｍｙｃ扩增，４１％有Ｎｍｙｃ扩增，与正常比差异均有显著意义（χ２＝６．７６４，７．６０９，５．９６１；Ｐ均＜００５）。Ｃｍｙｃ扩增率与用ＰＣＲ琼脂糖凝胶电泳检测的结果基本相符（χ２＝０．２５４，Ｐ＞００５）。结论此法对检测肿瘤组织中Ｍｙｃ基因３个成员提供了简易、特异、无放射污染，并且适于临床应用的、优于ＰＣＲ琼脂糖凝胶电泳的方法。     

RARα／MYL融合mRNA是诊断和监测急性早幼粒细胞白血病的特异标志

应用四条引物（Ｒ＿５，Ｒ＿６，Ｄ＿３，Ｄ＿４）通过逆转录聚合酶链反应（ＲＴ－ＰＣＲ）检测了２０例初治急性早幼粒细胞白血病（ＡＰＬ）患者的ＲＡＲα／ＭＹＬ融合ｍＲＮＡ。建立的方法可在０．１ｎｇ细胞总ＲＮＡ中检出ＲＡＲα／ＭＹＬ融合ｍＲＮＡ，相当于在１０￣４～１０￣５个正常细胞中检出一个ＡＰＬ细胞，扩增产物的特异性经ＫｐｎＩ酶切法确认。１８例患者表达Ｂ型融合ｍＲＮＡ（２９０ｂｎ片段），２例表达Ａ型（３１１ｂｐ片段）。２例患者在完全缓解（ＣＲ）达４周和１６周时仍可检出融合ｍＲＮＡ。１例患者在ＣＲ期ＲＴ－ＰＣＲ检测持续阳性，４周后；临床复发。４例在ＣＲ期随访９～２９周融合ｍＲＮＡ均阴性。２例急性白血病在维甲酸治疗前拟诊ＡＰＬ，但ＲＴ。ＰＣＲ检测阴性，这２例对维甲酸治疗无效，核型分别是ｔ（８；２１）和正常。我们认为，ＲＡＲα／ＭＹＬ融合ｍＲＮＡ与ＭＹＬ／ＲＡＲα融合ｍＲＮＡ一样，也是诊断和监测ＡＰＬ的一个敏感和特异的标志。     

HpaⅡ—PCR检测小儿急性白血病降钙素基因高度甲基化

应用聚合酶链反应（ＰＣＲ）结合ＨｐａⅡ限制性内切酶消化法（ＨｐａⅡ－ＰＣＲ）检测５８例急性白血病（ＡＬ）患儿降钙素（ＣＴ）基因的甲基化状态。病例组待检细胞ＤＮＡ经ＨｐａⅡ消化后，再用两对ＣＴ基因特异性引物作ＰＣＲ扩增，分别产生长度为５６６ｂｐ和１．４ｋｂ特异片段。急性淋巴细胞白血病阳性率７１．４％（２５／３５），急性非淋巴细胞白血病７８．２％（１８／２３）。敏感性达１０－３。证明ＣＴ基因５′高度甲基化是白血病细胞克隆的特异标志。本课题受卫生部、四川省人民医院出国人员基金资助     

聚合酶链反应限制性片段长度多态性检测载脂蛋白E基因型

目的建立一种简便、准确、实用的人载脂蛋白Ｅ（ａｐｏＥ）基因型的检测方法。方法应用聚合酶链反应（ＰＣＲ）特异性扩增ａｐｏＥ基因含编码１１２位和１５８位氨基酸的基因序列，扩增产物用限制性内切酶ＨｈａⅠ酶切，聚丙烯酰胺凝胶电泳后，观察酶切位点的限制性片段长度多态性（ＲＦＩＰ）图谱。结果运用ＰＣＲ－ＲＦＬＰ法检测了１１３名健康人ａｐｏＥ基因型，频率分别为ε３／３６９．０％，ε３／２１６．８％，ε４／３１１．５％，ε４／２１．８％，ε４／４０．９％；ε２、ε３和ε４等位基因频率分别是９．３％、８３．２％和７．５％。结论该方法简单、快速、准确，对人体无害，适合于一般实验室开展及大规模人群调查     

在HeLa细胞中表达人βIVS-Ⅱ-nt 654C→T突变基因

目的：建立一个能表达人βＩＶＳ－Ⅱ－ｎｔ６５４Ｃ→Ｔ突变基因（β６５４基因）的ＨｅＬａ细胞模型。方法：应用长片段多聚酶链反应（ＰＣＲ）技术从一例β６５４突变基因纯合子的基因组ＤＮＡ中扩增出β６５４基因全长片段，重组进ｐｃＤＮＡ３．１真核表达载体质粒中。经ＤＮＡ测序证明序列中确实含有β６５４突变后，将重组表达质粒用脂质体方法转化ＨｅＬａ细胞，用逆转录－多聚酶链反应（ＲＴ－ＰＣＲ）方法检测β６５４突变基因在转染细胞中表达的ｍＲＮＡ。结果：该重组表达质粒能在ＨｅＬａ细胞中转录β６５４突变基因，并剪接成正常和异常两种ｍＲＮＡ（对应于１８３ｂｐ和２５６ｂｐ两种ＲＴ－ＰＣＲ产物），而对照组无扩增条带出现。结论：重组表达质粒转化的ＨｅＬａ细胞能表达β６５４基因。     

Compensatory increase in alpha 1-globin gene expression in individuals heterozygous for the alpha-thalassemia-2 deletion.

alpha-Globin is encoded by the two adjacent genes, alpha 1 and alpha 2. Although it is clearly established that both alpha-globin genes are expressed, their relative contributions to alpha-globin messenger RNA (mRNA) and protein synthesis are not fully defined. Furthermore, changes that may occur in alpha-globin gene activity secondarily to the loss of function of one or more of these genes (alpha-thalassemia [Thal]) have not been directly investigated. This study further defines the expression of the two human alpha-globin genes by determining the relative levels of alpha 1 and alpha 2 mRNA in the reticulocytes of normal individuals and in individuals heterozygous for the common 3.7-kilobase deletion within the alpha-globin gene cluster that removes the alpha 2-globin gene (the rightward type alpha-Thal-2 deletion). To quantitate accurately the ratio of the two alpha-globin mRNAs, we have modified a previously reported S1 nuclease assay to include the use of 32P end-labeled probes isolated from alpha 1- and alpha 2-globin complementary DNA recombinant plasmids. In individuals with a normal alpha-globin genotype (as determined by Southern blot analysis [alpha alpha/alpha alpha]), alpha 2-globin mRNA is present at an average 2.8-fold excess to alpha 1. In individuals heterozygous for the rightward type alpha-Thal-2 deletion (-alpha/alpha alpha) the alpha 2/alpha 1 mRNA ratio is 1:1. These results suggest that the loss of the alpha 2-globin gene in the alpha-Thal-2 deletion is associated with a 1.8-fold compensatory increase alpha 1-globin gene expression.     

βIVS—Ⅱ—1 G→A复合三联α基因所致的韩国人中间型β地中？…

目的 研究中间型β地中海贫血的分子机制,为中间型β地中海贫血的基因诊断提供科学依据。方法 应用聚合酶链反应（ＰＣＲ）,Ｓｏｕｔｈｅｒｎ印迹杂交和双链ＤＮＡ循环测序等技术,对在韩国首次发现的中间型β地中海贫血家系的α和β珠蛋白基因进行分析。结果 基因分析表明,该家系属典型的中间型β地中海贫血,它的分子病因是β珠蛋白基因的第２内含子５‘端的第１个碱基Ｇ→Ａ（ＩＶＳ－Ⅱ－１Ｇ→Ａ）突变和三联α珠蛋白基因     

广东地区β地中海贫血复合缺失型α地中海贫血双重杂合子检出率

目的 研究广东地区β地中海贫血（地贫）杂合子复合α地贫双重杂合金的检出率。方法 采用反向点杂交法（RDB）诊断β地贫杂合子500例并进一步采用Gap-PCR法进行α地贫1基因检测,用α珠蛋白基因探针Southern印迹杂交限制性核酸内切酶酶谱分析法对其中400例β地贫杂合子中有26例合并α地贫2,其中17例为右侧缺失（αα／－α^3.7),9例为左侧缺失（αα/-α^4.2)。结论 广东地区β地贫杂合子复合α地贫1的检出率为8．6％,复合α地贫2的检出率为6．5％,其中复合右侧缺失型α地贫2的检出率为4．2％,复合左侧缺失型α地贫2的检出率为2．2％。     

Organization of the alpha-globin genes in the Chinese alpha-thalassemia syndromes.

The alpha-thalassemia syndromes are a group of inherited anemias, the clinical severity of which has been shown to increase with the number of alpha-globin structural genes deleted. Employing restriction endonuclease gene mapping, we defined the organization of the alpha-globin genes in cellular DNA from Chinese subjects with various alpha-thalassemia syndromes. The four alpha-globin genes of normals are at two loci located on a 23.0-kilobase pair (kb) Eco RI fragment. In deletion type hemoglobin-H disease the 5' alpha-globin locus is deleted and the single 3' alpha-globin locus is found on a 19.0-kb Eco RI fragment. In alpha-thalassemia-2 there are two alpha-globin genes on a 23.0-kb Eco RI fragment and one on a 19.0-kb fragment. In alpha-thalassemia-1 and the nondeletion type of hemoglobin-H disease the two alpha-globin genes are at two loci on one chromosome and none reside on the other chromosome.     

Two different molecular organizations account for the single alpha-globin gene of the alpha-thalassemia-2 genotype.

The alpha-thalassemia-2 (alpha-thal-2) genotype or mild alpha-thalassemia gene consists of a single structural alpha-globin gene on the chromosome that normally bears two alpha-globin genes. We used blot hybridization to investigate variation in the molecular organization of this genotype and to determine the distributions of these variations in the world population. Two different patterns of gene organization responsible for the alpha-thal-2 genotype were found: the first was the result of a 4.2-kilobase pair deletion involving the normal 5' alpha-globin gene (leftward deletion alpha-thal-2 genotype), and the second probably the result of a crossover deletion of a DNA fragment bridging the two normal alpha-globin genes (rightward deletion alpha-thal-2- genotype). The rightward deletion was found in all 9 Black subjects, all 8 Mediterranean subjects, and 4 of 13 Chinese subjects. The leftward deletion was found in four and the nondeletion alpha-thalassemia lesion was found in five of the nine remaining Chinese subjects. It is likely that these deletions are related to specific DNA sequences that determine DNA recombinational events.     

东南亚缺失型α地中海贫血的聚合酶链反应快速诊断技术及产前诊断

目的　针对东南亚缺失型α地中海贫血 (- - SEA)建立一种快速、简便的聚合酶链反应(PCR)基因诊断技术 ,并初步应用于高危胎儿的产前诊断。方法　采用跨越断裂点的PCR设计方案 ,其中一对引物用于扩增 - - SEA缺失基因 ,另一对引物设计在 - - SEA、-α3 .7、-α4 .2 的公共缺失区域 ,用于扩增正常的α珠蛋白基因 ,两对引物在单管中反应。用该方法对 8例高风险Bart’s水肿胎进行产前诊断。结果　 - - SEA缺失基因的扩增产物为 740bp ,正常等位基因的扩增产物为 10 5 2bp。进行产前诊断的 8例高风险Bart’s水肿胎 ,检出正常胎儿 3例 ,- - SEA杂合子 3例 ,HbBart’s水肿胎儿 2例。结论　该法快速、准确 ,可作为常规方法用于临床样品的分子筛查及Bart’s水肿胎和缺失型HbH病的产前诊断。     

多重PCR用于缺失型α-地中海贫血的基因检测

为了探讨多重PCR技术在检测我国南方常见缺失型α—地中海贫血中的临床应用，观察缺失型α—地中海贫血的基因分布频率，采用单管多重DNA扩增的方法(M—PCR)对经血红蛋白定量分析初步诊断为标准型和静止型α—地中海贫血及血红蛋白H(HbH)病的145例患者进行基因检测。扩增产物经1．2％琼脂糖凝胶电泳，出现1．3及1．8kb条带者，提示为-^SEA／αα；1．6及1．8kb条带者为-α^4.2／αα；1．8及2．0kb条带者为-α^3.7／αα；1．3及1．6或2．0kb条带，提示为缺失型HbH病(-^SEA／-α^4.2或-^SEA／-α^3.7)。结果表明，145例受检者中发现100例-^SEA／αα(68．9％)，15例-α^3.7/ αα(10．3％)，8例-α^4.2/αα(5．52％)，2例-α^3．7／-α^4.2(1．38％)，-α^3.7及-α^4.2纯合子各1例(0．69％)；14例-SEA／αα(9．65％)，2例-SEA／-α^4.2(1．38％)；另有2例患者产前诊断证实为Bart水肿胎儿。结论：运用多重PCR技术可以准确、简便、快速地检测我国南方地区常见的-α^3.7、-α^4.2、-^SEA3种缺失型α-地中海贫血，这一技术对α—地中海贫血的大人群筛查及携带者的检出是一种较为理想的方法。     

Rapid differentiation of five common alpha-thalassemia genotypes by polymerase chain reaction

The alpha-thalassemias are common genetic disorders that arise from reduced synthesis of the alpha-globin chains. At present, large-scale carrier screening and clinically valuable antenatal detection programs have not been established for the congenital disorder alpha-thalassemia (alpha-thal). We have developed a simple nonradioactive polymerase chain reaction (PCR) approach that can detect and differentiate several common alpha-globin gene deletional alpha-thals regardless of the break points. When three primer sets were used--two gene-specific sets for the alpha1- and alpha2-globin genes and one set for the beta-actin gene (serving as an internal control)--PCR products from genomic DNA were simultaneously amplified and analyzed after coamplification and gel electrophoresis. The number of alpha-globin genes present in the subjects was determined by the intensity of alpha1 and alpha2 bands normalized with that of beta-actin when using densitometry. Our results demonstrate that five common genotypes of deletional alpha-thal are differentiated by the ratios of alpha1/beta-actin and alpha2/beta-actin. We also examined the feasibility of coupling this allele-specific amplification to a color-complementary assay. This easy and reproducible PCR assay is suitable for identifying alpha-thal carriers in screenings of large populations and improving genetic counseling.     

Severe hemophilia A due to a 1.3 kb factor VIII gene deletion including exon 24: homologous recombination between 41 bp within an Alu repeat sequence in introns 23 and 24.

Partial or complete factor (F)VIII gene deletions are found in about 5% of families with severe hemophilia A. Relatively few deletions have been well characterized and, of these, recombination occurred between either common repeat elements or non-homologous sequences. In evaluating a family with severe hemophilia A, an exon 24 deletion was suspected when no fragment was obtained on attempted PCR amplifications. A combination of the 5' primer of exon 23 and the 3' primer of exon 25 fragments was used with prolonged extension times to amplify a normal 2.9 kb fragment that included exons 23 through 25; the patient's amplified product was 1.6 kb indicating a 1.3 kb deletion. A mixture of normal and patient DNA showed both sized fragments as did that from an obligate carrier. Carrier detection was applied to two women at risk; one was and one was not a carrier. Sequencing the proband's 1.6 kb fragment revealed that a 1328 bp deletion occurred between homologous sequences of 287 and 285 bp in introns 23 and 24, respectively; these share 85% identity. Blast nucleotide search revealed that these represent Alu elements. Comparison with an alignment of each of the two homologous sequences further localized recombination to a 41-bp segment. However, a simple recombination event would not account for the proband's sequence. The most likely explanation is that the homologous recombination was accompanied by incomplete mismatch repair.