pVAX1-microdystrophin重组质粒的构建及其治疗Duchenne型肌营养不良症的初步研究

目的 构建含有人microdystrophin基因的重组质粒,体内、外研究其表达,为进一步应用此重组质粒来研究电转、静脉、动脉注射或加入其它基因来增强microdystrophin基因的表达等方法对Duchenne型肌营养不良(Duchenile muscular dystrohy,DMD)进行基因治疗奠定基础.方法 用Not Ⅰ酶切含microdystrophin基因的pBSK-MICRO质粒,获得microdystrophin基因.片段回收后定向插入真核表达质粒pVAX1,获得重组质粒pAMICDYS.然后将重组质粒pAMICDYS转染小鼠成纤维细胞3T3细胞,通过逆转录-PCR以及间接免疫荧光检测microdystrophin的转录及蛋白表达;最后将重组质粒pAMICDYS通过肌肉注射到DMD模型鼠胫前肌中,检测治疗肌肉的病理变化和microdystrophin的表达情况.结果 成功构建了含有microdystrophin基因的重组质粒,并在体外得到了很好表达,体内研究表明microdystrophin基因在mdx鼠TA也有一定程度的表达,而且减少了所治疗肌肉的核中移数量,证实了其对mdx鼠有一定的治疗作用.结论 该重组质粒的构建及体内、外得到成功表达,为下一步用该质粒进行电转、静脉、动脉注射或加入其它基因来增强microdystrophin基因的表达来治疗DMD疾病奠定了基础.     

Duchenne型肌营养不良症的产前基因诊断研究

应用Ｄｕｃｈｅｎｎｅ型肌营养不良症（Ｄｕｃｈｅｎｎｅ　ｍｕｓｃｕｌａｒ　ｄｙｓｔｒｏｐｙ，ＤＭＤ）基因的ｃＤＮＡｓ作为探针，以限制性片段长度多态（ＲＦＬＰ）分析为策略，采用Ｓｏｕｔｈｅｒｎ分子杂交方法，成功地对１例可疑ＤＭＤ的男性胎儿及１例ＤＭＤ患儿进行基因诊断。结果显示该胎儿ＤＭＤ基因正常，而患儿存在ＤＭＤ基因缺失（缺失２．１５ｋｂ）。在基因分析前，应用聚合酶链式反应（ｐｏｌｙｍｅｒａｓｅ　ｃｈａｉｎ　ｒｅａｃｔｉｏｎ，ＰＣＲ）技术鉴定胎儿性别为男性。胎儿出生后检查结果与与产前基因诊断相吻合。为了获得高灵敏度探针，本文采用地高辛配基标记ＤＮＡ探针的方法，通过酶联免疫法，使分子杂交的ＤＮＡ检测带出现颜色反应。实验结果表明，此方法适用于基因组单拷贝ＤＮＡ顺序的检测，具有快速、安全等优越性，可以替代同位素进行推广、应用。     

外显子跳跃治疗Duchenne型肌营养不良症的研究进展

Duchenne型肌营养不良症是一种致死性肌肉疾病,抗肌萎缩蛋白基因缺陷是导致本病的原因,目前本病尚无特效的疗法.反义寡核苷酸(antisense oligonucleotides,AOs)诱导的外显子跳跃作为一种新的治疗手段具有良好的应用前景.本文主要从外显子跳跃治疗的原理、基础研究及临床研究进行综述.     

进行性肌营养不良患者视网膜眼电图表型与临床分型及基因型的关系

目的 研究进行性肌营养不良（Duchenne/Becker muscular dystrophy,DMD/BMD)患者视网膜眼电图（electroretinogram,ERG)表型与临床分型以及基因型的关系。进一步探讨不同基因型的DMD患者抗肌营养不良蛋白（dystrophin)及其同源蛋白在视网膜上的表面爱功能,揭示DMD出现ERG异常的分子机理,方法 用11对引物对22例临床确诊的DMD／BMD患者作三步多重PCR进行基因缺失分析,并行ERG检查,结果 DMD／BMD患者ERG改变与临床分型及病情严重程度无关,与DMD／BMD的基因型有关,基因中央区缺失型的ERG异常率明显高于基因非缺失型,结论 DMD／BMD的ERG改变与DMD基因突变位点有关,可能DP260转录启动子与视网膜电信号的传导关系最密切。     

Duchenne型肌营养不良症家系的多重PCR和STR—PCR基因诊断

目的该研究率先开展温州地区Duchenne型肌营养不良症（DMD）家系的缺失基因诊断特别是STR单体型连锁基因诊断,为基于DMD症状前、携带者基因诊断结果的遗传咨询和生育指导提供依据。方法针对4例DMD先证者,采用多重PCR检测常见18个外显子缺失,进行直接基因诊断。针对未能发现常见外显子缺失的DMD先证者及其有关家系成员,采用短串联重复序列（STR）PCR检测5个位点（3’CA、44CA、45CA、49CA和50CA）STR多态性,进行间接单体型连锁基因诊断。结果家系二的先证者缺失外显子3、4和6。其余3个家系的先证者的异常x染色体均肯定来源于其母亲。家系一先证者外婆肯定是携带者。家系三先证者年幼（4周岁）弟弟肯定为正常人,将来年龄大了也不会发病,先证者外婆肯定是携带者。家系四先证者刚出生的妹妹肯定是遗传携带者,将来其生育儿子有遗传患病风险。结论该研究的DMD家系的缺失和STR单体型连锁基因诊断,特别是对症状前男孩的诊断、对无患病后代的女性携带者的检出,具有非常重要的实际意义,可以为遗传咨询和生育指导提供可靠依据。     

两种不同Duchenne型肌营养不良症模型鼠神经肌肉接头结构的比较

BACKGROUND: Neuromuscular junction structure has defects in patients with Duchenne muscular dystrophy, mainly presenting acetylcholine receptor structure fragmentation and the reduction of spine-like processes on the  postsynaptic membrane. It is generally recognized that the structural defects are induced by structural damage of muscle cells and muscle fiber necrosis. OBJECTIVE: To explore the reasons of damage on neuromuscular junction in mouse models of Duchenne muscular dystrophy.  METHODS: We introduced Duchenne muscular dystrophy models of male mdx mice and male Dko mice. After gene identification, they were used for tests. Male C57BL/6 mice were selected as normla controls. Hematoxylin-eosin staining was utilized to detect pathological changes in muscles. Neuromuscular junction structure was revealed using immunofluorescence staining. The differences in dystrophin expression, pathological features and neuromuscular junction structure were compared in mouse models of two kinds of Duchenne muscular dystrophy.  RESULTS AND CONCLUSION: The introduced mouse models were accorded with the requirement of our experiment in aspects of genotype and protein expression levels. The number of acetylcholine receptor was apparently reduced in the neuromuscular junction of two kinds of mouse models. Although dko mouse muscles presented more obvious inflammatory infiltration and muscle fiber damage compared with mdx mice, but there was no significant difference in the damage to neuromuscular junction between them, and acetylcholine receptor fragmentation was identical. The evidence suggested that structural damage of neuromuscular junction and inflammatory pathological response are independent events. There is no direct relationship between them. Dystrophin gene deficiency is the main cause of the fragmentation of the acetylcholine receptor.        

脂肪干细胞移植对Duchenne型肌营养不良症鼠神经肌肉再生单位的影响

背景：目前,Duchenne型肌营养不良症尚无有效治疗方法,之前的研究表明基因治疗和干细胞移植治疗是可能的“治愈”方法。实验拟将两者结合起来,在动物模型上观察其疗效,并验证之前提出的神经肌肉再生单位的假说。 目的：探讨脂肪干细胞移植治疗Duchenne型肌营养不良症的有效性和可行性,观察细胞移植对肌纤维、新生血管及神经末梢的影响。 方法：体外分离培养mdx鼠脂肪干细胞,经杆状病毒基因载体进行基因修饰,用于移植治疗Duchenne型肌营养不良症模型鼠。移植后检测实验动物的血清肌酸激酶水平、肌肉病理改变及肌肉内dystrophin表达;免疫荧光检测细胞移植后血管、肌肉和神经再生情况。 结果与结论：细胞移植后,能够重建模型鼠的dystrophin表达,一定程度上减轻并逆转肌肉的病理损害,进而降低血清激酸激酶水平;此外,细胞移植后能够形成干细胞来源的肌纤维、血管内皮细胞和神经末梢。这些证据表明,脂肪干细胞移植是有希望治疗Duchenne型肌营养不良症的方法之一。     

假肥大型肌营养不良症的基因型与临床表型关系分析

目的 分析中国人群假肥大型肌营养不良症基因型和临床表型之间的关系.方法 临床诊断Duchenne型肌营养不良症(Duchenne muscular dystrophy,DMD)和Becker型肌营养不良症(Becketmuscular dystrophy,BMD)患者,应用多重探针连接依赖性扩增技术进行DMD基因检测,将基因检测结果与临床诊断比较进行统计分析.结果 280例DMD基因缺失或重复患者中,DMD患者238例(85.0%),BMD患者35例(12.5%),中间型患者7例(2.5%).DMD或BMD符合阅读框原则的有252例,占92.31%(252/273),不符合阅读框的有21例,占7.69%(21/273).DMD基因为整码突变而患者表现为DMD的有12例(12/273,4.40%),移码突变而患者表现为BMD的有9例(9/273,3.30%).7例中间型患者均为移码突变.结论 阅读框假说可以解释大约90%DMD或BMD基因型与表现型关系,部分移码突变患者表型为BMD可有助于了解该病的发病机制,为未来治疗提供理论依据.     

Dysferlin缺陷:肢带2B型肌营养不良与Miyoshi肌病的致病原因

目的　对临床怀疑为常染色体隐性遗传性肌营养不良一家系进行分析 ,以明确肌病类型并寻找其致病基因的分子缺陷。方法　用与 8种常染色体隐性遗传性肌营养不良基因连锁的短串联重复序列标记进行连锁分析 ,用与 5种肌营养不良相关的单克隆抗体作多重免疫印迹分析检测相应致病基因的编码产物 ;通过逆转录 - PCR扩增先证者致病基因的编码序列并测序 ,确定基因突变。结果　家系连锁分析显示在 DYSF基因附近的 D2 S337位点的优势对数记分值为 1.85 ,提示致病基因与 D2 S337连锁 ;免疫印迹分析提示患者DYSF基因的编码产物 dysferlin缺陷 ;测序证明先证者DYSF基因的c DNA第 6 4 2 9位发生纯合性del G突变。结论　综合研究结果和临床资料 ,这一家系中的先证者被诊断为 Miyoshi肌病 ,由DYSF基因纯合性缺失突变所导致。     

A study of possible heterogeneity in Duchenne muscular dystrophy

One possible explanation for the apparently high birth incidence of Duchenne muscular dystrophy (DMD), a lethal X-linked disorder, is genetic heterogeneity. As a first step in possibly demonstrating genetic heterogeneity, affected boys were sub-divided into those with and without severe mental handicap. In those with severe mental handicap, ages at onset and of becoming confined to a wheelchair were later, the fall in SCK level with age was less marked, and the urinary excretion of certain aminoacids was greater than in affected boys with normal intelligence. Though the number of subjects investigated was relatively small (15 in each group) and further studies are therefore needed, the results suggest that DMD may not be a single disease entity.     

Variable dystrophin expression in different muscles of a Duchenne muscular dystrophy carrier

The majority of Duchenne muscular dystrophy (DMD) female carriers show dystrophin immunostaining abnormalities, although a significant proportion of clinically non-manifesting carriers are normal following this analysis. We had the opportunity to study dystrophin immunostaining in two different muscles, the vastus lateralis and the rectus abdominis of a possible DMD carrier. While the vastus showed normal dystrophin immunostaining, pathological staining was detected in her rectus abdominis. These findings seem to indicate that dystrophin expression can vary in different muscle groups of a DMD carrier. The implications of these findings in DMD carrier detection and possible dystrophin function are discussed.     

DGGE-based whole-gene mutation scanning of the dystrophin gene in Duchenne and Becker muscular dystrophy patients

Duchenne and Becker muscular dystrophy (DMD and BMD) are caused by mutations in the dystrophin gene. Large rearrangements in the gene are found in about two-thirds of DMD patients, with approximately 60% carrying deletions and 5-10% carrying duplications. Most of the remaining 30-35% of patients are expected to have small nucleotide substitutions, insertions, or deletions. To detect these subtle changes within the coding and splice site determining sequences of the dystrophin gene, we established a semiautomated denaturing gradient gel electrophoresis (DGGE) mutation scanning system. The DGGE scan covers the dystrophin gene with 95 amplicons, PCRed either individually or in a multiplex setup. PCR and pooling were performed semiautomatically, using a pipetting robot and 384-well plates, enabling concurrent amplification of DNA of four patients in one run. Amplification of individual fragments was performed using one PCR program. The products were pooled just before gel loading; DGGE requires only a single gel condition. Validation was performed using DNA samples harboring 39 known DMD variants, all of which could be readily detected. DGGE mutation scanning was applied to analyze 135 DMD/BMD patients and potential DMD carriers without large deletions or duplications. In DNA from 25 out of 44 DMD patients (57%) and from 5 out of 39 BMD patients (13%), we identified clear pathogenic changes. All mutations were different, with the exception of one DMD mutation, which occurred twice. In DNA from 10 out of 44 potential DMD carriers, including four obligate carriers, we detected causative changes, including one pathogenic change in every obligate carrier. In addition to these pathogenic changes, we detected 15 unique unclassified variants, i.e., changes for which a pathogenic nature is uncertain.     

A survey of manifesting carriers of Duchenne and Becker muscular dystrophy in Wales

Manifesting carriers of Duchenne and Becker muscular dystrophy are uncommon but well described. Such patients are of particular importance with regard to the differential diagnosis from autosomal recessive limb-girdle muscular dystrophy. All mothers of affected males known to the Genetic Register of Muscular Dystrophy Families in Wales were contacted, and 167 out of a possible 190 were examined. It was estimated from pedigree and creatine kinase analysis that 119 out of the 167 were carriers of the Duchenne/Becker gene. Three manifesting carriers were identified, giving the proportion affected as 3/119 = 2.5%. We estimate the prevalence of manifesting carriers to be 1 in 100,000 of the female population, a figure comparable to the prevalence of autosomal recessive limb-girdle muscular dystrophy. During the period of the survey, several other women with similar clinical findings but without an appropriate family history were seen. We strongly suspect that some of these are also manifesting carriers of the Duchenne/Becker gene.     

Molecular deletions in the Duchenne/Becker muscular dystrophy gene

To gain further information relating to the frequency, position and size of DNA deletions in the Duchenne/Becker muscular dystrophy (D/BMD) gene region, and to detect any correlation of these deletions with phenotype, a large clinic-based population of DMD and BMD patients has been investigated using 13 cloned intragenic sequences. Our of 263 separate patients studied, 75 showed a deletion of at least one locus (28.5%). These represented 25.6% (55/215) of DMD patients and 41.7% (20/48) of BMD patients, suggesting that the milder phenotype is more often likely to be due to a deletion. The deletions range from 6 kilobases (kb) to greater than 1000 kb in size. The distribution of deletions across the gene region shows at least one region (detected by P20) prone to deletion mutations in both DMD and BMD patients. There is no simple correlation of position or extent of deletions with DMD or BMD, although deletion of a specific region towards the 5' end of the gene may be more often associated with a milder phenotype. Apparently similar deletions can give rise to phenotypes differing significantly in severity, presumably indicating further complexities in the molecular or cellular pathology.     

Intragenic deletions in 164 boys with Duchenne muscular dystrophy (DMD) studied with dystrophin cDNA

DNA from 164 unrelated Duchenne muscular dystrophy patients was screened with cDNA probes from the dystrophin gene. Molecular deletions were demonstrated in 82 (50%) subjects. Sixty-two deletions (76%) were detected using cDNA probes Cf56a (cDNA 8) and Cf56b (cDNA 6-7) which map to the centre of the gene, while 22 deletions (27%) mapped to the 5' end of the gene. In three subjects, the deletion extended from the 5' end to the centre of the gene. One deletion was identified by probe 47-4 (cDNA 5b-7) alone. In six of the deletions, junction fragments of altered size were observed. Using the three cDNA probes, RW2kb, Cf56a (cDNA 8) and Cf56b (cDNA 6-7), 99% of the deletions were detected. This will have implications for prenatal diagnosis in deletion families. Unlike Becker muscular dystrophy, where the deletions are more homogeneous, the deletions in the present study were heterogeneous both in size and position. No correlation between intelligence and either site or extent of deletion was found.     

Genetic epidemiology of Duchenne and Becker muscular dystrophy in Slovenia

Most population studies on Duchenne (DMD) and Becker (BMD) muscular dystrophies predated the discovery of the gene and its product dystrophin. The diagnosis of these conditions and consequent epidemiological estimates were therefore limited to clinical criteria. In our study of the Slovene population the prevalence and cumulative incidence of DMD and BMD were calculated by including additional diagnostic tests: deletion screening in the dystrophin gene as well as dystrophin immunocytochemistry. The minimal prevalence rates, 2.9/100000 for DMD, 1.2/100000 for BMD, and the minimal cumulative DMD incidence rate of 13.8/100000 are in the range of lower estimates compared to studies world-wide. However, we found a high BMD cumulative incidence rate of 5.7/100000 and a high proportion of BMD versus DMD cumulative incidence rate (41.3%). Our results imply that the epidemiological figures for BMD might have been underestimated in the past.     

Relatively low proportion of dystrophin gene deletions in Israeli Duchenne and Becker muscular dystrophy patients

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are allelic disorders caused by mutations in the X-linked dystrophin gene. The most common mutations in western populations are deletions that are spread non-randomly throughout the gene. Molecular analysis of the dystrophin gene structure by hybridization of the full length cDNA to Southern blots and by PCR in 62 unrelated Israeli male DMD/BMD patients showed deletions in 23 (37%). This proportion is significantly lower than that found in European and North American populations (55–65%). Seventy-eight percent of the deletions were confined to exons 44–52, half of these to exons 44–45, and the remaining 22% to exons 1 and 19. There was no correlation between the size of the deletion and the severity of the disease. All the deletions causing frameshift resulted in the DMD phenotypes. © 1994 Wiley-Liss, Inc.     

Duchenne muscular dystrophy and myotonic dystrophy in the same patient

We report on the first patient identified with myotonic dystrophy and Duchenne muscular dystrophy (DMD). The family of the propositus had a strong history of myotonic dystrophy, and there was an intrafamilial pathological expansion of the responsible CTG repeat between the mildly affected mother (160 repeats; normal 27 repeats) and her more severely affected son (650 repeats), and his sister (650 repeats). The propositus was an isolated case of Duchenne muscular dystrophy with marked dystrophin deficiency in muscle biopsy. The patient was still ambulatory post age 16. Myotonic dystrophy could interfere to some extent with the progression of Duchenne dystrophy. However, other interpretations are possible. Twelve percent of dystrophin revertant fibers as observed by immunohistochemistry could be sufficient to ameliorate typical DMD clinical severity, or the patient may present a somatic mosaic. The pathophysiological interactions of these two unlinked disorders are discussed at the clinical and histopathological levels. © 1995 Wiley-Liss, Inc.