Asymptomatic Becker muscular dystrophy in a family with a multiexon deletion

We report a Becker muscular dystrophy (BMD) family with one 5‐year‐old affected patient and a 69‐year‐old asymptomatic grandfather. Dystrophin gene multiplex polymerase chain reaction and multiplex ligation‐dependant probe amplification analysis showed that both males carried an in‐frame deletion of exons 45–55. Segregation analysis revealed two additional asymptomatic boys in this family. Our finding supports previous predictions that exons 45–55 are the optimal multiexon skipping target in antisense gene therapy to transform the severe Duchenne muscular dystrophy into the milder BMD, or even asymptomatic, phenotype. Muscle Nerve, 2008     

Therapy of MS

The era of disease-modifying drugs (DMDs) in multiple sclerosis (MS) treatment began in the 1990s, first with interferon-β (IFNβ), and the number of agents has increased steadily since then. Currently, there are six different parenteral formulations approved for MS treatment and many other oral and parenteral ones are in different stages of investigation or awaiting approval by federal agencies.     

DMD/BMD基因诊断及其临床分析(附33例报告)

目的:研究Duchenne/Becker型肌营养不良症(DMD/BMD)患者致病基因外显子缺失的分布特点及其与临床表现的关系。方法:利用9对引物以多重PCR技术对33例DMD/BMD患者进行致病基因诊断。结果:9对引物外显子缺失总检出率为45.5％,主要分布在中央缺失热区和5′端缺失热区,其中以45、48号外显子缺失最多见。且缺失片段长度各异。结论:(1)该病病情轻重可能与基因缺失的外显子数量及片段大小不呈平行关系,而与某些外显子缺失有关。(2)致病基因的表达也受到个体差异的影响,呈高度的遗传异质性。     

定量多重PCR在筛查DMD携带者和产前诊断中的应用

基于抗肌萎缩蛋白基因(DMD)多个外显子进行对数增长期多重PCR(多聚酶链反应)产物定量分析的原理,本研究在改进Ioannou等方法基础上建立了假性肥大型肌营养不良症(DMD/BMD)定量多重PCR(QM-PCR)技术,应用于携带者筛查和产前诊断.运用多重PCR技术对12个DMD/BMD家系先证者的检测表明缺失一个或一个以上外显子的家系有7个(58.3%).QM-PCR证实7名缺失型患者中6名母亲是与缺失型患者相同的携带者(86.7%).1例检测出外显子缺失的DMD患者,其母亲及外祖母的外周血淋巴细胞DNA未发现任何DMD基因缺失,可以排除为携带者(13.3%).对一名肯定携带者妊娠9周的胎儿进行了性别测定和DMD检测,确诊胎儿为男性DMD患者.一例可能携带者在排除携带者基础上,进一步对妊娠胎儿产前诊断确诊为正常女婴.本研究的结果进一步证实了该技术筛查DMD携带者的可靠性.将本技术与其它技术相结合可明显改进DMD家系中携带者诊断的准确性,并可应用于谱系及多态性信息不详家系的携带者诊断.该技术对防止缺失型DMD患儿和携带者的出生有重要的意义.     

散发型DMD/BMD家系突变分析及产前诊断研究

目的 分析散发型DMD/BMD家系中患者的致病突变,为部分家系的胎儿进行产前基因诊断,明确该类家庭中女性成员是否致病突变携带者,分析该类家系新发突变的比例.方法 共收集30个散发DMD/BMD家系,应用传统mPCR方法 分析DMD基因缺失热区中的18个外显子;应用MLPA方法,对家系中的30例患者及23个家系中的28位女性成员,进行DMD基因全部79个外显子的定量分析,并为其中19个家系进行20例产前诊断.结果 mPCR检测到19例缺失突变;MLPA检测到21例缺失突变和3例重复突变,并明确缺失突变范围.在检测到突变的家系中,10例母亲为缺失突变携带者,2例为重复突变携带者,9例母亲不是携带者,新发突变比例为37.5%.7例患者的姐妹中5例为携带者(3例缺失,2例莺复),2例不是携带者.经产前诊断,12例男性胎儿中5例为患者,8例女性胎儿中2例为携带者.结论 MLPA方法 可全面检测DMD基因缺失及重复突变、明确女性携带者,为产前诊断提供准确信息.     

Large majority of single-nucleotide mutations along the dystrophin gene can be explained by more than one mechanism of mutagenesis

The present study reports for the first time on the analysis of the possible origin of single-base mutations along the highly mutable human dystrophin gene. Seventy-two mutations were considered and analyzed for consistency with the “slipped-mispairing” and “hypermutable CpG” models of mutagenesis. Moreover, repeated and symmetric elements, which could participate in the formation of secondary structures, were searched in each stretch of sequence including a given mutant base. Unexpectedly, the frequency of CpG mutations was found less than reported for other genes, whereas the frequency of transitions was found to be much higher than expected. Base substitutions in CpG dinucleotides that could be explained by methylation-mediated deamination were all C→T transitions. No G→A transitions in CpG dinucleotides were found. A sequence motif, which has been shown to act as an arrest site for polymerase α, occurred associated with < 50% of single-base mutations. All the mutations but one can be explained by at least two mechanisms of mutagenesis. This would mean that mutation could occur with higher probability at a given position, when it might be produced independently by different mechanisms. According to the present data, direct or inverted repeats seem to play a major role in this context. Therefore, the search for repeats along the dystrophin gene might help in identifying potential sites of mutation. Hum. Mutat. 9:537–547, 1997. © 1997, Wiley-Liss. Inc.     

重组腺相关病毒（rAAV）介导基因SMCKA3999对Duchenne肌营养不良病理和功能的影响

目的　 研究重组腺相关病毒 (rAAV)载体介导的dystrophin小基因SMCKA3999治疗DMD模型鼠mdx ,从病理和功能观察rAAVSMCKA3999治疗对DMD模型小鼠mdx的疗效。方法　以dystrophin小基因SMCK A3999为目的基因 ,将SMCKA3999克隆至rAAV并包装成rAAVSMCKA3999,以 5× 10 10 病毒颗粒单点注射于DMD模型鼠mdx腓肠肌 ,基因治疗后 4个月及 7个月 ,采用免疫荧光、光镜组织病理、肌电图等方法 ,从形态和功能观察rAAVSMCKA3999治疗对DMD模型小鼠mdx的疗效。 结果　rAAVSMCKA3999使肌膜缺失的dys trophin恢复并稳定表达持续 7个月以上 ,肌肉组织病理改变好转 ,肌病肌电图改变明显改善 ,疗效持续 4个月以上。 结论　rAAVSMCKA3999能改善mdx小鼠骨骼肌的病理及功能 ,采用rAAV介导的dystrophin小基因SMC KA3999对Duchenne肌营养不良基因治疗是有希望的治疗方法。     

多重聚合酶链反应检测DMD／BMD患者的基因缺失

目的了解Duchenne型肌营养不良（DMD）／Becker型肌营养不良（BMD）患者基因缺失的分布规律,并探索检测技术。方法应用28对引物多重聚合酶链反应（mPCR）分4组对20例DMD／BMD患者进行Dysophin基因缺失检测分析。结果12例（60％）存在外显子缺失,8例（40％）未检测到缺失;8例缺失片段集中于44—52号外显子,4例集中于5’端外显子。结论基因缺失为主要突变类型,缺失片段主要分布于44—52、2～20号外显子两个缺失热区。