抗肌萎缩蛋白的疏水结构与DMD／BMD的关系

用Ｇｅｎｅｐｒｏ程序在计算机上分析抗肌萎缩蛋白的疏水性和亲水性，首次发现该蛋白存在４个疏水肽段，分别位于第９５～１２０，１９９０～２０１０，２４３８～２４９３和３１５０～３３００位氨基酸。其中第３疏水肽段（２４３８～２４９３位氨基酸）的疏水性最强，由抗肌萎缩蛋白基因第５１号外显子碥码，称之为缺失热区疏水肽段。通过对６５例整码缺失的ＤＭＤ和１３６例整码缺失的ＢＭＤ病例分析，７５％（４９例）的ＤＭＤ患者缺失热区疏水肽段消失，９８％（１３３例）的ＢＭＤ患者缺失热区疏水肽段存在。提示缺失热区疏水肽段是抗肌萎缩蛋白的一个重要结构功能区。     

免疫荧光检测抗肌萎缩蛋白诊断肌营养不良症的临床应用

目的 采用免疫荧光技术对Duchenne型肌营养不良症（Duchenne muscular dystrophy,DMD),Becker型肌营养不良症（Becker muscular dystrophy,BMD)，面肩肱型肌营养不良症（facioscapulohumeral muscular dystrophy,FSHD)以及神经性肌萎缩患者骨骼肌细胞膜的dystrophin蛋白进行检测，为临床诊断、分类肌营养不良症提供简便的实验方法。方法 对47例患者选择3种dystrophin 的鼠抗单克隆抗体、羊抗和兔抗多克隆抗体，分别进行免疫荧光技术检测。结果 16例DMD患者均为阴性染色；11例BMD患者为弱阳性染色；10例FSHD和10例神经性肌萎缩患者均为阳性染色。结论 检测肌营养不良症患者骨骼肌膜dystrophin蛋白，有助于肌营养不良症的临床诊断和分型。     

Duchenne肌营养不良基因缺陷及基因治疗

Duchenne肌营养不良(DMD)是常见的神经肌肉遗传病之一,由于骨胳肌肌膜上的抗肌萎缩蛋白(dystrophin)完全或部分缺失引起.本文介绍了dystrophin的结构和功能,对DMD基因治疗的目的基因,基因治疗方式(包括病毒载体和非病毒载体),基因转染途径作了较为全面的介绍,指出腺相关病毒载体介导的基因治疗及干细胞移植是有希望的治疗方向,经全身途径使目的基因广泛转染骨胳肌并实现心肌和膈肌的转染,是基因治疗研究的难点.     

DMD的基因、细胞和药理学治疗研究进展

杜兴氏肌营养不良（Duchenne muscular dystrophy，DMD）是一种X连锁隐性遗传的进行性肌萎缩疾病，主要由抗肌萎缩蛋白基因缺陷引起。抗肌萎缩蛋白是一种肌纤维膜结构蛋白，在维持肌细胞膜结构完整性中起重要作用。目前此疾病的治疗手段主要有基因治疗、细胞治疗和药理学治疗。针对疾病的根本原因，基因治疗和细胞治疗通过传递正常基因或修正突变基因以及移植正常细胞，如干细胞来进行治疗；药理学治疗则主要针对抗肌萎缩蛋白基因缺陷引起的下游事件，运用各种药物来减缓DMD病理进程．从而改善患者的生活质量．延长寿命。主要概述DMD治疗的最新讲展．并分析目前尚存存的问颢．     

抗肌萎缩蛋白基因非缺失/重复突变引起的Becker型肌营养不良症的研究

目的 探讨Becker型肌营养不良症(Becker muscular dystrophy,BMD)的基因突变类型,增加对抗肌萎缩蛋白基因非缺失/重复突变引起BMD的认识.方法 收集2例BMD患者的临床资料,应用多重连接依赖式探针扩增(multiplex ligation-dependent probe amplification assay,MLPA)方法对抗肌萎缩蛋白基因进行分析,并对其肌肉进行苏木素-伊红(hematoxylin-eosin,HE)染色、抗肌萎缩蛋白(dystrophin)染色及电镜检测.结果 2例患者经MLPA方法检测抗肌萎缩蛋白基因均呈非缺失/重复突变类型,肌肉活检光镜和电镜均呈肌营养不良改变.例1患者染色示肌膜dystrophin大部分呈不连续弱阳性,部分为阴性.例2患者染色示肌膜dystrophin-C为阴性,dystrophin-N为阳性.结论 对于抗肌萎缩蛋白基因非缺失/重复突变的临床症状较轻的患者,进行肌肉活检和抗肌萎缩蛋白免疫组化将有助于明确诊断BMD及判断其预后.

Abstract：

Objective To identify potential mutations in patients featuring Becker muscular dystrophy (BMD) and to enhance the understanding of non-deletion/duplication mutations of the dystrophin gene causing BMD. Methods linical data of two patients affected with BMD were collected. Potential mutations in the dystrophin gene were screened with multiplex ligation-dependent probe amplification assay (MLPA). Biopsied muscle samples were examined with HE staining, immnostaining with anti-dystrophin antibody, and electronic microscopy. Results MLPA assay suggested that both cases were probably due to non-deletion/duplication mutations of the dystrophin gene. Light and electronic microcopy of skeletal muscle biopsies confirmed dystrophic changes in both patients. For patient A, immunostaining showed non-contiguous weak staining for most parts of sarcolemma. For patient B, immunostaining showed positive result with N-terminal anti-dystrophin antibody and negative result with C-terminal anti-dystrophin antibody. Conclusion For patients with mild phenotypes but without dystrophin gene deletion/duplication, muscle biopsy and immunochemistry are helpful for diagnosis and prognosis.     

两家同胞肌营养不良与脊肌萎缩症肌电图分析

肌营养不良(muscular dystrophy)为一组遗传性肌肉疾病。临床过程呈进行性．可在出生时即有，也可出生后数年才发病，大多数是由于原发性肌肉损伤所致．表现为肌纤维的变性。目前公认的诊断方法为根据遗传特点、发病年龄、病肌分布、进展速度以及肌肉变性的程度而确定。肌营养不良主要有四种：①Duchenne型；②Becker型；③面肩肱型；     

应用DNA微阵列技术检测缺失型DMD/BMD患者的研究

目的研究Duchenne型肌营养不良（DMD）/Becker型肌营养不良（BMD）患者基因缺失检测的可行技术。方法应用分子克隆的方法扩增DMD基因18个常见易缺失外显予片段，以此作为探针制备出简易DNA微阵列，对30例DMD/BMD患者和5例健康对照的基因进行检测分析。部分结果与PCR方法比较结果一致性。结果应用简易DNA微阵列检测出21例DMD/BMD患者具有不同程度的外显予缺失，10例经PCR检测得到了完全验证。结论DNA微阵列技术检测缺失型DMD/BMD患者简便、准确、灵敏，具有临床应用价值。     

STR-PCR联合SRY-PCR方法在DMD点突变家系产前基因诊断中的应用

目的对点突变型假肥大型肌营养不良症（Duchenne＇s muscular dystrophy,DMD）患者的家系采用STR-PCR联合SRY-PCR分析方法进行产前基因诊断。方法采用STR-PCR连锁分析方法和SRY-PCR方法对20个点突变型DMD家系进行产前基因诊断。结果男性胎儿40%（8/20）,其中患胎62.5%（5/8）;女性胎儿60%（12/20）,其中携带者58.3%（7/12）。结论 STR-PCR连锁分析方法结合SRY-PCR方法用于点突变型DMD家系的产前诊断,是目前一种快速、简便、准确和可行的方法。     

假肥大型进行性肌营养不良的诊断与遗传分析

目的总结假肥大型进行性肌营养不良患者的临床特征、病因及病理变化,提高其诊治水平。方法对患者进行肌电图、磷酸肌酸激酶浓度、肌肉活体组织、智力、神经反射等项检查,收集完整的家系资料进行遗传分析,判断致病基因携带者并评估再发风险。结果得到一假肥大型进行性肌营养不良的家系,并进一步确定其X连锁隐性遗传的遗传方式,明确了患者的表型特征,总结了目前的诊治方法,给与家系中相关人员以必要的遗传指导。结论假肥大型进行性肌营养不良是抗肌萎缩蛋白基因发生突变所致,目前应用PCR的相关技术、变性高效液相色谱结合测序技术可对突变基因进行筛查,从而预防患者的出生,对该病的治疗已取得了一定的进展。     

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.     

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.     

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.     

DMD and BMD in the same family due to two distinct mutations

We report on a family with a boy affected by Duchenne muscular dystrophy (DMD) and an asymptomatic cousin with a Beckertype dystrophin abnormality, diagnosed by chance. Dystrophin gene analysis showed that these conditions were caused by two distinct deletions with breakpoints in different exons. In Xp21 families, DNA analysis and dystrophin testing of asymptomatic males with high CK plasma levels might detect different dystrophin mutations in separate haplotypes as in our family, although we stress there should be clear clinical or familial indications for such testing. © 1995 Wiley-Liss, Inc.     

Sensitivity and frequencies of dystrophin gene mutations in Thai DMD/BMD patients as detected by multiplex PCR

Background: Duchenne muscular dystrophy (DMD), a lethal X-linked disease affecting 1 in 3500 male births, and its more benign variant, Becker muscular dystrophy (BMD), are caused by mutations in the dystrophin gene. Because of its large size, analysing the whole gene is impractical. Methods have been developed to detect the commonest mutations i.e. the deletions of the exons. Although these tests are highly specific, their sensitivity is inherently limited by the prevalence of deletions, which differs among different populations. Methods: We reviewed our database for the detection of Dystrophin gene mutation by means of 31-exon multiplex PCR in Thai males, diagnosed clinically and biochemically with DMD or BMD from July 1994 to November 2006. One index patient was chosen from each family for statistical analysis. The overall sensitivity of the test, the number of fragment deleted, and the deletion frequency of each fragment were calculated, along with their 95% confidence intervals (C.I.). Results: We found deletions in 99 out of the 202 index patients (49%; Bayesian 95% C.I. = 42%–56%). 51% of these had deletion in only one of the 31 exons tested, while the patient with the most extensive deletions had 14 exons deleted. The mean number of deleted exons were 2.84 (BC_a bootstrap 95% C.I. = 2.37–3.48), or 5.02 (3.81–6.85) if all the untested exons adjacent to the confirmed deleted exons were assumed to be deleted. The region spanning exons 44-52 was the most frequently deleted. These were similar to those reported in the Japanese. Conclusion: The multiplex PCR detected deletions only in about half of the Thai patients. The diseases therefore should not be excluded solely on the negative result if DMD/BMD is strongly suspected.     

Novel point mutations in the dystrophin gene

Duchenne (DMD) and Becker (BMD) type muscular dystrophies are allelic X-linked recessive disorders caused by mutations in the gene encoding dystrophin. About 65% of the cases are caused by deletions, while 5–10% are duplications. The remaining 30% of affected individuals may have smaller mutations (point mutations or small deletions/insertions) which cannot be identified by current diagnostic screening strategies. In order to look for pathogenic small mutations in the dystrophin gene, we have screened the 18 exons located in the hot spot region of this gene through two different single strand conformation polymorphism (SSCP) conditions. Five different pathogenic mutations were identified in 6 out of 192 DMD/BMD patients without detectable deletions: 2 nonsense, 1 bp insertion, 1 bp deletion and 1 intronic. Except for the intronic change, which alters a splice site, all the others cause a premature stop codon. In addition, 8 apparently neutral changes were identified. However, interestingly, one of them was not identified in 195 normal chromosomes, although it was previously described in a DMD patient from a different population. The possibility that this mutation may be pathogenic is discussed. Except for two neutral changes, all the others are apparently here described for the first time. Hum Mutat 10:217–222, 1997. © 1997 Wiley-Liss, Inc.     

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.     

Amplification of ten deletion-rich exons of the dystrophin gene by polymerase chain reaction shows deletions in 36 of 90 Japanese families with Duchenne muscular dystrophy

We analyzed DNA samples taken from 95 Duchenne muscular dystrophy (DMD) patients belonging to 90 different families in Japan using the polymerase chain reaction. Ten different regions at the 5′ end or in the central region of the dystrophin cDNA gene that were previously shown to be prone to deletion were selected for amplification and analysis. Patients in 36 of the 90 families (40%) had deletions in at least one of these segments of the gene. Identical deletions were detected in the dystrophin gene of patients from the same family. The deletions were heterogeneous in size and location. One patient had deletions in 7 of the 10 amplified regions, while 19 patients from 18 families had a deletion in only one of the regions studied. Deletions at the 5′ end were generally larger and more heterogeneous than those in the central region of the gene. One third of deletions had their proximal end breakpoints between exons 44 and 45. This region seems to be particularly vulnerable to gene breakage in DMD patients.     

Array-MLPA: comprehensive detection of deletions and duplications and its application to DMD patients

Multiplex ligation-dependent probe amplification (MLPA) is widely used to screen genes of interest for deletions and duplications. Since MLPA is usually based on size-separation of the amplification products, the maximum number of target sequences that can be screened in parallel is usually limited to approximately 40. We report the design of a robust array-based MLPA format that uses amplification products of essentially uniform size (100-120 bp) and distinguishes between them by virtue of incorporated tag sequences. We were thus able to increase probe complexity to 124, with very uniform product yields and signals that have a low coefficient of variance. The assay designed was used to screen the largest set studied so far (249 patients) of unrelated Duchenne muscular dystrophy (DMD) cases from the Chinese population. In a blind study we correctly assigned 98% of the genotypes and detected rearrangements in 181 cases (73%); i.e., 163 deletions (65%), 13 duplications (5%), and five complex rearrangements (2%). Although this value is significantly higher for Chinese patients than previously reported, it is similar to that found for other populations. The location of the rearrangements (76% in the major deletion hotspot) is also in agreement with other findings. The 96-well flow-through microarray system used in this research provides high-throughput and speed; hybridization can be completed in 5 to 30 minutes. Since array processing and data analysis are fully automated, array-MLPA should be easy to implement in a standard diagnostic laboratory. The universal array can be used to analyze any tag-modified MLPA probe set.     

The ZZ Domain of Dystrophin in DMD: Making Sense of Missense Mutations

Duchenne muscular dystrophy (DMD) is associated with the loss of dystrophin, which plays an important role in myofiber integrity via interactions with β‐dystroglycan and other members of the transmembrane dystrophin‐associated protein complex. The ZZ domain, a cysteine‐rich zinc‐finger domain near the dystrophin C‐terminus, is implicated in forming a stable interaction between dystrophin and β‐dystroglycan, but the mechanism of pathogenesis of ZZ missense mutations has remained unclear because not all such mutations have been shown to alter β‐dystroglycan binding in previous experimental systems. We engineered three ZZ mutations (p.Cys3313Phe, p.Asp3335His, and p.Cys3340Tyr) into a short construct similar to the Dp71 dystrophin isoform for in vitro and in vivo studies and delineated their effect on protein expression, folding properties, and binding partners. Our results demonstrate two distinct pathogenic mechanisms for ZZ missense mutations. The cysteine mutations result in diminished or absent subsarcolemmal expression because of protein instability, likely due to misfolding. In contrast, the aspartic acid mutation disrupts binding with β‐dystroglycan despite an almost normal expression at the membrane, confirming a role for the ZZ domain in β‐dystroglycan binding but surprisingly demonstrating that such binding is not required for subsarcolemmal localization of dystrophin, even in the absence of actin binding domains.