MJD1基因单个碱基多态性与CAG重复序列不稳定性的关系

马查多－约瑟夫病患者的ＭＪＤ１基因存在ＣＡＧ三核苷酸不稳定扩展突变，为探讨这种不稳定扩展突变的分子机制。方法对５８名正常人和２０名ＭＪＤ患者的ＭＪＤ１基因内ＣＡＧ／ＣＡＡ、ＣＧＧ／ＧＧＧ两个位点的多态性进行检测。结果正常染色体中，具有ＣＧＧ等位基因的ＣＡＧ重复数目（２７．３２±０．６１，ｎ＝２８）较具有ＧＧＧ等位基因的ＣＡＧ重复数目（１５．９０±０．６９，ｎ＝３０）明显大（Ｐ＜０．０１）。ＣＧＧ等位基因在患者中的分布频率（１００％）明显高于正常人（４８．３％）。结论ＭＪＤ１基因内单个碱基置换影响ＣＡＧ重复序列的稳定性。     

Machado－Joseph病基因CAG重复数目与临床相关性

为了探讨Ｍａｃｈａｄｏ－Ｊｏｓｅｐｈ病（ＭＪＤ）的发病机理，分析了来自４个家系的６１名成员及１８名健康人的基因（ｃｙｔｏｓｉｎｅａｄｅｎｉｎｅｇｕａｎｉｎｅ，ＣＡＧ）重复数目后，发现所有１５例患者均存在ＣＡＧ重复扩展，其重复数目为７２～８６。正常人ＣＡＧ重复数目为１４～４０，两者之间差异有显著意义。另外，发现发病年龄与ＣＡＧ重复数目呈明显的负相关。２例发病年龄为５岁和１１岁的青少年患者，ＣＡＧ重复数目分别为８６和８３，大于所有成年发病的患者，且病情进展快，症状严重。临床症状与ＣＡＧ重复数目无明显相关性。进一步分析家系各代ＣＡＧ重复数目时，发现ＣＡＧ重复数目存在代间不稳定，这种不稳定性是临床遗传早现现象的分子基础     

马查多-约瑟夫病/脊髓小脑型共济失调Ⅲ型患者(CAG)n拷贝数与临床特征

目的探讨马查多约瑟夫病基因１（ＭＪＤ１）ＣＡＧ三核苷酸动态突变及其拷贝数与ＭＪＤ／脊髓小脑型共济失调Ⅲ型（ＳＣＡ３）患者临床特征的相关关系。方法应用聚合酶链式反应、变性聚丙烯酰胺凝胶电泳和银染技术，对９个ＭＪＤ／ＳＣＡ３家系１０９名成员进行ＭＪＤ１基因（ＣＡＧ）ｎ拷贝数分析。结果发现异常扩增的（ＣＡＧ）ｎ拷贝数与发病年龄呈负相关，并在一定程度上影响病情严重程度；主要临床症状、体征与异常扩增的（ＣＡＧ）ｎ拷贝数无关，而是受病程影响。同时发现１７例症状前患者。结论异常扩增的（ＣＡＧ）ｎ拷贝数对疾病表型有影响，但不能完全作为临床特征的预测指标     

Machado—Joseph病基因CAG重复数目与临床相关性

为了探讨Ｍａｃｈａｄｏ－Ｊｏｓｅｐｈ病的发病机理，分析了来自４个有系的６１名成员及１８名健康人的基因重复数目后，发现所有１５例患者均存在ＣＡＧ重复扩展，其重复数目为７２－８６。正常ＣＡＧ重复数目为１４－４０，两者之间差异有显著意义。     

三核苷酸重复的检测在脊髓小脑型共济失调的应用研究

目的建立中国人遗传性脊髓小脑型共济失调（ＳＣＡ）患者的ＳＣＡ１、ＳＣＡ２、ＳＣＡ３／ＭＪＤ、ＳＣＡ６型的ＣＡＧ三核苷酸重复（ＣＡＧ）ｎ频率的检测方法并探讨其诊断意义。方法应用聚合酶链式反应（ＰＣＲ）和６％变性聚丙烯酰胺凝胶电泳技术,检测了３０例正常人和６例临床诊断为ＳＣＡ患者上述４型的（ＣＡＧ）ｎ重复数。结果３０例正常人（ＣＡＧ）ｎ的重复数目分别为ＳＣＡ１６～４０次,ＳＣＡ２２２～２９次,ＳＣＡ３１３～３６次,ＳＣＡ６４～１６次。６例ＳＣＡ患者中２例有ＳＣＡ３异常,（ＣＡＧ）ｎ重复数分别为６７和７５,而ＳＣＡ１、ＳＣＡ２、ＳＣＡ６型（ＣＡＧ）ｎ重复数均在正常范围内。结论研究三核苷酸重复频率的检测为ＳＣＡ患者提供了准确可靠的诊断方法和标准。     

癫痫状态大鼠海马GAD67mRNA,GABA—TmRNA表达水平的动态观察

为了研究癫痫状态下大鼠海马区ＧＡＤ６７ｍＲＮＡ、ＧＡＢＡ－ＴｍＲＮＡ的表达水平，采用马桑内酯（ｃｏｒｉａｒｉａｌａｃｔｏｎｅ，ＣＬ）侧脑室注射所致大鼠癫痫状态模型，动态观察ＣＬ致痫前后大鼠海马ＧＡＤ６７ｍＲＮＡ、ＧＡＢＡ－ＴｍＲＮＡ表达水平的变化，同时观察了动物行为学改变及脑电图变化。实验结果显示，侧脑室注射ＣＬ后约１５分钟，大鼠海马及皮质ＥＥＧ出现阵发性棘慢波及高波幅慢波；ＣＬ注射后１５～３０分钟，实验鼠均出现明显的连续发作性四肢抽动、尖叫等症状，且持续６～８小时。ＣＬ侧脑室注射后３０分钟、１小时、２小时、４小时或８小时各时限点组大鼠海马ＧＡＤ６７ｍＲＮＡ表达水平均低于正常对照组。ＣＬ注射后３０分钟组大鼠海马ＧＡＢＡ－ＴｍＲＮＡ表达水平高于正常对照组，但３０分钟后各时限组ＧＡＢＡ－ＴｍＲＮＡ表达水平与正常对照组比较增加不明显。提示ＣＬ所致癫痫持续状态的后期，大鼠海马ＧＡＤ６７ｍＲＮＡ、ＧＡＢＡ－ＴｍＲＮＡ表达信号的减弱，可能与致痫因素及癫痫持续后期合并的缺血、缺氧性脑损害致使海马区ＧＡＤ、ＧＨＢＡ－Ｔ免疫反应阳性细胞死亡有关。     

重症肌无力患者周围血中CD4+T淋巴细胞亚群的研究

目的研究ＣＤ４＋Ｔ淋巴细胞的功能亚群在重症肌无力（ｍｙａｓｔｈｅｎｉａｇｒａｖｉｓ，ＭＧ）发病中的作用。方法采用免荧光双标记技术和流式细胞仪对３９例ＭＧ患者和１８例健康对照者周围血中ＣＤ４＋Ｔ淋巴细胞的两个亚群（ＣＤ４＋ＣＤ４５ＲＡ＋、ＣＤ４＋ＣＤ４５ＲＡ－）的百分率进行测定。结果ＣＤ４＋ＣＤ４５ＲＡ＋亚群的百分率在ＭＧ组和ＡＣｈＲＡｂ阳性组明显低于对照组和ＡＣｈＲＡｂ阴性组；而ＣＤ４＋ＣＤ４５ＲＡ－细胞的百分率在ＭＧ组和ＡＣｈＲＡｂ阳性组显著高于对照组和ＡＣｈＲＡｂ阴性组。结论表明ＣＤ４＋Ｔ淋巴细胞的两个功能不同亚群在ＭＧ患者体内发生了异常改变，与ＡＣｈＲＡｂ的产生有关。     

强直性肌营养不良基因CTG重复数与EMG,NCV对比分析

目的：探讨强直性肌营养不良ＤＭ患者及家系成员三核苷酸重复数ＣＴＧ（胞嘧啶、胸腺嘧啶、鸟嘌呤）的变化与ＥＭＧ、ＮＣＶ的关系。方法：用聚合酶链反应（ＰＣＲ）扩增及ＤＮＡ杂交法对５例临床诊断ＤＭ患者及三个家系的１６名成员进行ＤＭ基因的ＣＴＧ重复数和ＥＭＧ、ＮＣＶ测定，结果：１０名正常人ＣＴＧ重复数是３０个，ＥＭＧ、ＮＣＶ正常、５例ＤＭ病人ＣＴＧ重复数均在８５个以上，其中２例在１６０５个以上，明显高于正常     

强直性肌营养不良病人的三核苷酸数目的检测

目的　检测强直性肌营养不良（ Ｄ Ｍ ）病人的三核苷酸重复数目。方法　采用３２ Ｐ 标记的 Ｐ Ｃ Ｒ 和聚丙烯酰胺凝胶电泳技术，对 ３ 例 Ｄ Ｍ 病人的外周血和肌活检组织的 Ｃ Ｔ Ｇ 重复数目进行了分析。结果　３ 例 Ｄ Ｍ 病人 Ｃ Ｔ Ｇ 重复扩增片段分别为 １４６ｂｐ、１４９ｂｐ 和 １４９ｂｐ，相应的 Ｃ Ｔ Ｇ 重复数为 １１、１２、１２，其基因型为 １１／１１、１２／１２、１２／１２。结论　 Ｄ Ｍ 病人的 Ｃ Ｔ Ｇ 重复数目大多在 ５０～４０００ 不等，但是少数病人的 Ｃ Ｔ Ｇ 重复数目可在正常范围，一般认为是遗传异质性或基因突变所致。 Ｃ Ｔ Ｇ 重复数目正常的病人并不能排除 Ｄ Ｍ 的诊断。     

重症肌无力患者烟碱型乙酰胆碱受体抗体致鼠脑干？…

目的神经肌接头（ＮＭＪ）处乙酰胆碱（ＡＣｈ）传递障碍，是重症肌无力（ＭＧ）发病机制，然而，近年有研究表明部分ＭＧ患者有中枢神经系统（ＣＮＳ）受损的症状和神经电生理方面的异常表现，本研究为探讨其机制。方法 从烟碱型乙酰胆碱受体抗体（ｎＡＣｈＲ－ａｂ）阳性的全身型ＭＧ患者血清中提取ＩｇＧ将其注入ＳＤ大鼠脑室系统，观察其对脑干听觉诱发电位（ＢＡＥＰ）的影响。结果 ｎＡＣｈＲ－ａｂ使脑干听觉传导功能异常，     

Autosomal dominant cerebellar ataxia type I in Morocco: presence of the SCA1 and SCA3/MJD mutations

We searched for CAG repeat expansions at the SCA1 and SCA3/MJD loci in nine families, including 15 examined patients, with autosomal dominant cerebellar ataxia type I from Morocco. Expansion of the CAG repeat was found in one family at the SCA1 and two at the SCA3/MJD locus, demonstrating the existence of genetic heterogeneity among ADCA type I families in Morocco. Instability during transmission was observed at both loci as in other unstable mutations. The phenotypes of the SCA1 and SCA3/MJD patients were similar.     

Progressive atrophy of cerebellum and brainstem as a function of age and the size of the expanded CAG repeats in the MJD1 gene in Machado-Joseph disease

Machado-Joseph disease (MJD) is an autosomal dominat neurodegenerative disease characterized by cerebellar ataxia associated to varying degrees with pyramidal signs, extrapyramidal signs, or peripheral amyotrophy. It is caused by unstable expansion of the CAG repeat in the MJD1 gene on chromosome 14q32.1. To determine how the neurodegenerative process in the central nervous system of patients with MJD correlates with the size of expanded CAG repeats in the MJD1 gene and other factors, we performed detailed quantitative analyses of findings of magnetic resonance imaging of the central nervous system of 21 patients with MJD of various ages and with various sizes of expanded CAG repeats. We found that atrophy of the brainstem and cerebellar vermis in MJD patients is closely correlated not only with the size of expanded CAG repeat in the MJD1 gene but also with patient age, which suggests that the neurodegenerative process in MJD is regulated by the size of expanded CAG repeats as well as by the patient age.     

Analysis of trinucleotide repeats in different SCA loci in spinocerebellar ataxia patients and in normal population of Taiwan

Objective – To identify various subtypes of spinocerebellar ataxias (SCAs) among autosomal dominant cerebellar ataxia (ADCA) patients referred to our research center, SCA1, SCA2, SCA3/MJD (Machado–Joseph disease), SCA6, SCA7, SCA8 and SCA12 loci were assessed for expansion of trinucleotide repeats.
Patients and methods – A total of 211 ADCA patients, including 202 patients with dominantly inherited ataxia from 81 Taiwanese families and nine patients with sporadic ataxia, were included in this study and subjected to polymerase chain reaction (PCR) analysis. The amplified products of all loci were analyzed on both 3% agarose gels and 6% denaturing urea-polyacrylamide gels. PCR-based Southern blots were also applied for the detection of SCA7 locus.
Results – The SCA1 mutation was detected in six affected individuals from one family (1.2%) with expanded alleles of 50–53 CAG repeats. Fourteen individuals from nine families (11%) had a CAG trinucleotide repeat expansion at the SCA2 locus, while affected SCA2 alleles have 34–49 CAG repeats. The SCA3/MJD CAG trinucleotide repeat expansion in 60 affected individuals from 26 families (32%) was expanded to 71–85 CAG repeats. As for the SCA7 locus, there were two affected individuals from one family (1.2%) possessed 41 and 100 CAG repeats, respectively. However, we did not detect expansion in the SCA6, SCA8 and SCA12 loci in any patient.
Conclusions – The SCA3/MJD CAG expansion was the most frequent mutation among the SCA patients. The relative prevalence of SCA3/MJD in Taiwan was higher than that of SCA2, SCA1 and SCA7.     

Machado-Joseph disease/SCA3 and myotonic dystrophy type 1 in a single patient

We report here, for the first time, the case of a 41-year-old man with both Machado-Joseph disease (MJD)/spinocerebellar ataxia type 3 (SCA3) and myotonic dystrophy type 1. The patient noted dysarthria at 14 years of age and unsteady gait at 30 years of age. Similar sized expansions of the CAG trinucleotide repeats in one allele of the ataxin-3 (ATXN3) gene were found in both the patient and his father, although in the other allele the length of the CAG repeats was shorter in the father compared with the patient. In the dystrophia myotonica protein kinase (DMPK) gene the CTG repeats were much more expanded in the patient compared with his father. Thus it is possible that, in the farther, the short CAG repeat in the non-expanded ATXN3 allele delayed the onset of cerebellar symptoms, and/or that the expanded CTG repeat in the DMPK gene in the patient accelerated the pathogenesis of MJD/SCA3.     

Age related axonal neuropathy in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD)

To identify determinants of peripheral involvement in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) the influence of CAG repeat length, age of onset, disease duration and age on the results of nerve conduction studies was analysed in 58 patients with SCA3/MJD. Patients with SCA3/MJD showed marked reduction of compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes indicating axonal neuropathy of both motor and sensory fibres. In addition, there was moderate slowing of nerve conduction suggestive of mild peripheral demyelination. Multivariate regression showed that CMAP and SNAP amplitudes decreased with age, but were not affected by CAG repeat length, age of onset, or disease duration. The age related decline of CMAP and SNAP amplitudes in SCA3/MJD was greater than in normal subjects. The data suggest that the degree of peripheral damage in SCA3/MJD does not depend on CAG repeat length, age of onset, or disease duration, but is mainly related to the time period over which the SCA3/MJD mutation exerts its effect.     

宁夏地区回、汉族脊髓小脑共济失调家系SCA3/MJD基因突变研究

目的通过对宁夏地区临床诊断为脊髓小脑共济失调的3个家系(2个汉族家系、1个回族家系)进行SCA3/MJD基因检测,探讨脊髓小脑共济失调的发病机制与临床特点,以为临床应用提供依据。方法对3家系受试者进行神经系统检查和系谱调查,部分行头部MRI和肌电图检查,以及SCA3/MJD基因胞嘧啶-腺嘌呤-鸟嘌呤(CAG)重复数目检测。结果3家系中共计8例脊髓小脑共济失调患者(汉族家系1中6例、汉族家系2中1例和回族家系中1例),符合常染色体显性遗传特点,以共济失调与构音障碍为主要表现,其次为眼外肌麻痹、眼球震颤、慢眼动、锥体束征等。其中汉族家系1和回族家系明确诊断为SCA3/MJD家系,两家系中7例患者(汉族家系1中6例、回族家系中1例)及2例临床表型正常亲属(两家系中各1例)检测出SCA3/MJD异常等位基因,其CAG重复数目为66～81次。汉族家系2中1例患者及汉族家系1中4例临床表型正常亲属SCA3/MJD基因CAG重复数目为20～33次。正常等位基因与异常等位基因CAG重复数目差异有统计学意义(t=5.309,P=0.000)。结论宁夏地区回、汉族脊髓小脑共济失调患者中存在SCA3/MJD基因型,基因检测分析有利于明确诊断脊髓小脑共济失调且能够检出症状前患者。     

Sharing of polyglutamine localization by the neuronal nucleus and cytoplasm in CAG-repeat diseases

The expansion of a trinucleotide cytosine adenine and guanine (CAG) repeat that codes for polyglutamine is a common gene mutation in the family of hereditary neurodegenerative diseases that includes Machado-Joseph disease (MJD) and dentatorubral-pallidoluysian atrophy (DRPLA). The presence of ubiquitinated neuronal intranuclear inclusions (NIIs) has been recognized as a neuropathological hallmark of these diseases, although the significance of NIIs in the pathogenesis remains a matter of controversy. In a previous study of DRPLA, we proposed that intranuclear diffuse accumulation of mutant proteins is another pathological characteristic of neurones, and that the variable prevalence of this characteristic may be relevant to the variation of clinical symptoms in patients with different repeat sizes. Recently, we also disclosed that polyglutamine tracts are localized in a subset of lysosomes in affected neurones. The present immunohistochemical study of autopsied MJD and DRPLA brains shows that the nucleus and cytoplasm of affected neurones share the subcellular distribution of expanded polyglutamine tracts, the pattern of distribution being specific to each diseased brain. The results suggest that in CAG-repeat diseases, mutant proteins are involved in both the ubiquitin/proteasome and endosomal/lysosomal pathways for protein degradation in different intraneuronal compartments, where their accumulation may exert distinct influences on neuronal physiology.     

Frequency of SCA1, SCA2, SCA3/MJD, SCA6, SCA7, and DRPLA CAG trinucleotide repeat expansion in patients with hereditary spinocerebellar ataxia from Chinese kindreds

OBJECTIVE: To assess the frequency of SCA1 (spinocerebellar ataxia type 1), SCA2, SCA3/MJD (spinocerebellar ataxia type 3/Machado-Joseph disease), SCA6, SCA7, and DRPLA (dentatorubropallidoluysian atrophy) CAG trinucleotide repeat expansions [(CAG)n] among persons diagnosed with hereditary SCA from Chinese families. PATIENTS AND METHODS: Spinocerebellar ataxia type 1, SCA2, SCA3/MJD, SCA6, SCA7, and DRPLA (CAG)n mutation were detected with the polymerase chain reaction, highly denaturing polyacrylamide gel electrophoresis, and silver staining technique in 167 patients with autosomal dominant SCA from 85 Chinese families and 37 patients with sporadic SCA. RESULTS: Spinocerebellar ataxia type 1 (CAG)n mutation in 7 patients from 4 kindreds (4.70%) was expanded to 53 to 62 repeats. Spinocerebellar ataxia type 2 (CAG)n mutation in 12 patients from 5 kindreds (5.88%) was expanded to 42 to 47 repeats. Spinocerebellar ataxia type 3/Machado-Joseph disease (CAG)n mutation in 83 patients from 41 kindreds (48.23%) was expanded to 68 to 83 repeats. Sixty-five patients from 35 kindreds (41.19%) and 37 patients with sporadic SCA did not test positive for SCA1, SCA2, SCA3/MJD, SCA6, SCA7, or DRPLA. There was a predictable inverse relationship between the number of CAG repeats and the age at onset for SCA3/MJD and SCA2. Clinically, dementia and hyporeflexia were more frequent in patients with SCA2, while spasticity, hyperreflexia, and Babinski signs were more frequent in patients with SCA3/ MJD, and those might be helpful in clinical work to primarily distinguish patients with SCA3/MJD and SCA2 from others with different types of SCA. CONCLUSIONS: The frequency of SCA3/MJD is substantially higher than that of SCA1 and SCA2 in patients with autosomal dominant SCA from Chinese kindreds, who are non-Portuguese. Clinical expressions of the various types of SCAs overlap one another; therefore, for clinical study it is important to make a gene diagnosis and genetic classification for patients with SCA.     

Trinucleotide repeats in 202 families with ataxia: a small expanded (CAG)n allele at the SCA17 locus

BACKGROUND: Ten neurodegenerative disorders characterized by spinocerebellar ataxia (SCA) are known to be caused by trinucleotide repeat (TNR) expansions. However, in some instances the molecular diagnosis is considered indeterminate because of the overlap between normal and affected allele ranges. In addition, the mechanism that generates expanded alleles is not completely understood. OBJECTIVE: To examine the clinical and molecular characteristics of a large group of Portuguese and Brazilian families with ataxia to improve knowledge of the molecular diagnosis of SCA. PATIENTS AND METHODS: We have (1) assessed repeat sizes at all known TNR loci implicated in SCA; (2) determined frequency distributions of normal alleles and expansions; and (3) looked at genotype-phenotype correlations in 202 unrelated Portuguese and Brazilian patients with SCA. Molecular analysis of TNR expansions was performed using polymerase chain reaction amplification. RESULTS: Patients from 110 unrelated families with SCA showed TNR expansions at 1 of the loci studied. Dominantly transmitted cases had (CAG)(n) expansions at the Machado-Joseph disease gene (MJD1) (63%), at SCA2 (3%), the gene for dentatorubropallidoluysian atrophy (DRPLA) (2%), SCA6 (1%), or SCA7 (1%) loci, or (CTG)(n) expansions at the SCA8 (2%) gene, whereas (GAA)(n) expansions in the Freidreich ataxia gene (FRDA) were found in 64% of families with recessive ataxia. Isolated patients also had TNR expansions at the MJD1 (6%), SCA8 (6%), or FRDA (8%) genes; in addition, an expanded allele at the TATA-binding protein gene (TBP), with 43 CAGs, was present in a patient with ataxia and mental deterioration. Associations between frequencies of SCA2 and SCA6 and a frequency of large normal alleles were found in Portuguese and Brazilian individuals, respectively. Interestingly, no association between the frequencies of DRPLA and large normal alleles was found in the Portuguese group. CONCLUSIONS: Our results show that (1) a significant number of isolated cases of ataxia are due to TNR expansions; (2) expanded DRPLA alleles in Portuguese families may have evolved from an ancestral haplotype; and (3) small (CAG)(n) expansions at the TBP gene may cause SCA17.