宁夏地区脊髓小脑性共济失调家系基因突变特征的研究

目的研究宁夏地区脊髓小脑性共济失调(SCA)患者基因突变的特征。方法用聚合酶链反应(PCR)、毛细管凝胶电泳(CGE)及DNA测序方法对1个临床诊断为SCAs的宁夏籍家系中6例SCA患者和4名亲属进行SCA3/Machado-Joseph disease(MJD)基因三核苷酸CAG重复序列检测。结果此家系中6例患者及1名表型正常的家系成员检测出异常SCA3/MJD等位基因,CAG重复数为66～81次;确诊为SCA3/MJD。其余3名家系成员CAG重复数正常(22～33次)。结论宁夏地区SCAs患者有SCA3/MJD亚型。提示基因检测对SCAs患者的明确诊断及分型有重要意义。     

痉挛性截瘫并共济失调表型的家系基因分析

以该院门诊收治的5例具有痉挛性截瘫合并共济失调表型的家系先证者为研究对象,运用高通量测序芯片结合毛细管电泳技术对这些家系先证者进行致病基因动态突变检测。发现了一个家系先证者携带有ATXN3/MJD1基因CAG重复84次,其妹妹CAG重复82次,其父CAG重复73次,该家系拟诊为遗传性脊髓小脑共济失调3型(SCA3/MJD)家系,并具有明显的临床异质性及遗传早现现象。建议对于兼有痉挛性截瘫及小脑性共济失调表型的患者,特别是具有显性遗传家族史的患者,应进行SCA3致病基因的动态突变检测,同时对家系内表型正常的成员应仔细查体,以防漏诊。     

脊髓小脑共济失调3型临床变异型特征及突变分析

目的 探讨脊髓小脑共济失调3型临床变异型特征.方法 应用CEQ8000核酸分析仪对1个表型为变形性肌张力障碍家系和2个表型为痉挛性截瘫家系的SCA3/MJD基因胞嘧啶-腺嘌呤-鸟嘌呤(CAG)重复序列进行基因片段分析.结果 基因学检查证实3个家系均为SCA3/MJD基因CAG重复扩增突变致病.结论 我国脊髓小脑共济失调3型存在变形性肌张力障碍和痉挛性截瘫的临床变异型.脊髓小脑共济失调3型的多种临床变异类型为调节因素假说提供了进一步的证据,并且提示在临床工作中应注意避免遗漏阳性家系.     

两遗传性脊髓小脑型共济失调7型家系的临床特征和基因突变研究

目的 探讨遗传性脊髓小脑型共济失调(SCA)7型(SCA7)的临床特征和基因突变.方法 采用聚合酶链反应(PCR)和琼脂糖凝胶电泳(AGE)等技术,检测临床诊断为SCA的5个家系26例患者和37例表型正常的家系成员的SCA7基因内CAG三核苷酸重复次数,对异常等位基因片段进行DNA测序,分析临床表现和基因突变的关系. 结果 2个SCA7家系患者的SCA7等位基因内CAG重复数目为44～50次;临床表现主要为共济失调、视力下降及视网膜色素变性.该家系内表型正常的家系成员SCA7等位基因CAG重复数目为10～30. 结论 CAG过度扩增为SCA7的致病原因,分子遗传学分析有助于SCA7的诊断.     

遗传性脊髓小脑型共济失调6型两个家系的临床特征及基因突变研究

目的 研究中国人遗传性脊髓小脑型共济失调6型(SCA6)的基因突变和临床特征。方法 应用聚合酶链反应(PCR)、聚丙烯酰胺凝胶电泳(PAGE)等技术，检测临床诊断脊髓小脑型共济失调(SCA)的120个家系210例患者和47例散发SCA患者的SCA6基因内CAG三核苷酸重复序列，并对异常等位基因片段进行DNA测序。结果 检出2个家系(4例患者)为SCA6，阳性率为1，7％，测序证实其异常等位基因的CAG重复数目为25和26。另253例SCA患者的SCA6等位基因CAG重复数目为7-17，健康人SCA6等位基因CAG重复数目为5-16。2个家系均存在遗传早现现象，异常扩展的CAG序列呈代间稳定性。结论 从临床及基因诊断方面首次确认中国大陆存在SCA6家系；CAG过度扩增为SCA6的致病原因。     

遗传性脊髓小脑型共济失调7型遗传学诊断及临床特征

目的研究中国人遗传性脊髓小脑型共济失调(SCA)7型(SCA7)的基冈突变和临床特征。方法应用聚合酶链反应(PCR)、聚丙烯酰胺凝胶电泳(PAGE)等技术对临床表现为SCA的92个家系112例患者和16例散发SCA患者的SCA7基因内CAG三核苷酸重复序列进行检测,对异常等位基因片段进行DNA测序,分析基因型和表型之间的关系,并与表型正常的家系成员和健康人对照。结果在1个SCA7家系的6位成员中检测出2例患者的SCA7等化基因内CAG重复数目为71;临床表现主要为共济失调、视力下降、黄蓝色盲及视网膜色素变性。该家系内表型正常的4位成员SCA7等位基因CAG重复数目为7～9,另126例临床表现为SCA的患者、71名表型正常的家系成员及60名健康对照者SCA7等位基因内CAG三核甘三酸重复数为6—21。结论CAG过度扩增为SCA7的致病原因,分子遗传学分析有助于SCA7的诊断;视网膜色素变性为SCA7的重要特征。     

脊髓小脑性共济失调6型的分子遗传学诊断及临床特点

目的 研究脊髓小脑性共济失调6型(SCA6)的基因诊断方法及临床特点。方法 对临床诊断为脊髓小脑性共济失调(SCA)的36个家系43例患者及38例散发患者，应用聚合酶链反应对SCA6基因含有CAG三核苷酸重复片段进行扩增，并对异常等位基因片段进行DNA测序，计算CAG重复次数；对2例SCA6患者临床资料进行分析。结果 正常人的SCA6等位基因CAG重复数目为10～13。本组检出家族性患者1例，散发患者1例，其异常等位基因内CAG重复数目分别为25、24。患者临床基本特征为缓慢进展的小脑性共济失调、眼震、构音障碍。结论 致病基因内CAG三核苷酸重复异常扩增是SCA6的确诊依据。SCA6的临床表现与其他SCA亚型无明显差别。     

遗传性脊髓小脑型共济失调7型一家系的临床及基因突变分析

目的研究中国人遗传性脊髓小脑型共济失调7型(SCA7)的基因突变和临床特征。方法应用聚合酶链反应(PCR)、聚丙烯酰胺凝胶电泳(PAGE)等技术对一个表现为共济失调、视力下降、视网膜变性的家系(6位成员,包括2个患者)的SCA7基因内CAG三核苷酸重复序列进行检测,并对异常等位基因片段进行DNA直接测序,分析基因型和表型之间的关系。结果检测出该家系内2个患者的SCA7等位基因CAG重复数目为71,而该家系内其他表型正常的SCA7等位基因CAG重复数目为7～9。结论CAG过度扩增为SCA7的致病原因,分子遗传学分析有助于SCA7的诊断以及症状前患者的预测。     

脊髓小脑性共济失调一家系的基因诊断

目的 对1个常染色体显性遗传的脊髓小脑性共济失调(SCA)家系进行基因诊断.方法 采用PCR技术,对一汉族SCA家系(包括3例患者及3位无症状成员)及50名正常对照者的SCA1 ～3基因进行检测,通过琼脂糖凝胶电泳和产物直接测序法计数等位基因内CAG三核苷酸重复次数.结果 该家系中所有成员SCA1、SCA2基因CAG三核苷酸重复次数在正常范围;3例患者SCA3 CAG重复次数分别为67、68和66次,1位无症状成员为71次.结论 该家系为SCA3,基因检测诊断出1例症状前患者.     

遗传性痉挛性截瘫患者MJD1基因的突变分析

目的探讨中国汉族人群中遗传性痉挛性截瘫(Hereditary Spastic Paraplegia,HSP或SPG)患者的MJD1基因突变特点,进一步探索HSP和遗传性脊髓小脑性共济失调(Spinocerebellar Ataxia,SCA)的遗传和临床异质性。方法应用聚合酶链反应、8%变性聚丙烯酰胺凝胶电泳和DNA T载体连接测序等方法对78例临床诊断为HSP的患者进行MJD1基因突变分析。结果在18个HSP家系中检出SCA3/MJD1家系2个,占11.1%,该2例家系均为常染色体显性遗传,2例家系先证者在临床上符合HSP的诊断标准,突变的MJD1等位基因CAG三核苷酸异常重复次数分别为65和69次,散发的HSP病例未发现MJD1等位基因的异常。结论HSP和SCA都具有明显的临床和遗传异质性,其表型在临床上有相互交叉现象,部分SCA3/MJD1患者临床上可为典型的痉挛性截瘫特征而无任何明显的共济失调表现。对临床表现为HSP的患者,尤其是有明显阳性家族史的患者进行MJD1基因诊断可以弥补HSP临床诊断的不足。     

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.     

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.     

Spinocerebellar Ataxias in Brazil—Frequencies and Modulating Effects of Related Genes

This study describes the frequency of spinocerebellar ataxias and of CAG repeats range in different geographical regions of Brazil, and explores the hypothetical role of normal CAG repeats at ATXN1, ATXN2, ATXN3, CACNA1A, and ATXN7 genes on age at onset and on neurological findings. Patients with symptoms and family history compatible with a SCA were recruited in 11 cities of the country; clinical data and DNA samples were collected. Capillary electrophoresis was performed to detect CAG lengths at SCA1, SCA2, SCA3/MJD, SCA6, SCA7, SCA12, SCA17, and DRPLA associated genes, and a repeat primed PCR was used to detect ATTCT expansions at SCA10 gene. Five hundred forty-four patients (359 families) were included. There were 214 SCA3/MJD families (59.6 %), 28 SCA2 (7.8 %), 20 SCA7 (5.6 %), 15 SCA1 (4.2 %), 12 SCA10 (3.3 %), 5 SCA6 (1.4 %), and 65 families without a molecular diagnosis (18.1 %). Divergent rates of SCA3/MJD, SCA2, and SCA7 were seen in regions with different ethnic backgrounds. 64.7 % of our SCA10 patients presented seizures. Among SCA2 patients, longer ATXN3 CAG alleles were associated with earlier ages at onset (p?<?0.036, linear regression). A portrait of SCAs in Brazil was obtained, where variation in frequencies seemed to parallel ethnic differences. New potential interactions between some SCA-related genes were presented.     

Frequency of spinocerebellar ataxia mutations in the Kinki district of Japan

OBJECTIVES: To determine the frequencies of spinocerebellar ataxias (SCAs) in the Kinki district, the western part of the main island of Japan. MATERIAL AND METHODS: One hundred and forty-three families with dominantly inherited ataxia and 220 patients with apparently sporadic cerebellar ataxia were examined for the SCA1, SCA2, SCA3/Machado-Joseph disease (MJD), SCA6, SCA7, SCA8, SCA12 and dentatorubral-pallidoluysian atrophy (DRPLA) mutations. RESULTS: Among the dominant families, SCA1 accounted for 3%, SCA2 for 4%, SCA3/MJD for 24%, SCA6 for 31% and DRPLA for 12%. Neither SCA7 nor SCA12 mutations were detected. Among the apparently sporadic patients, 15% were found to have expanded triplet repeats. Of these, the SCA6 mutation was most frequently detected. CONCLUSION: SCA6 is the most common SCA in the Kinki district of Japan. Comparison of our results with those from other regions of Japan and different countries shows geographic and ethnic variation in the frequency of SCAs.     

Dominantly inherited ataxias: lessons learned from Machado-Joseph disease/spinocerebellar ataxia type 3

To date, nearly 30 distinct genetic forms of dominantly inherited ataxia are known to exist. Of these, Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is perhaps the most common in many regions of the world including the United States. This article discusses MJD/SCA3 as a paradigm example of the dominant ataxias, which are collectively known as the spinocerebellar ataxias. Using MJD/SCA3 as a starting point, the article reviews common clinical and genetic features of the SCAs and highlights new insights into molecular mechanisms, especially of the SCAs caused by polyglutamine expansion. Also discussed are current and future therapeutic opportunities for MJD/SCA3 in particular, many of which have relevance to other SCAs.     

中国汉族人群SCA1、2、3、6、7、8、10、12、17亚型和齿状核-红核-苍白球-路易体萎缩亚型频率分布

目的 研究中国汉族人群中脊髓小脑性共济失调(SCAs)不同基因亚型的频率分布.方法 运用聚合酶链反应、变性聚丙烯酰胺凝胶电泳、Southern blot、T载体克隆重组DNA技术结合直接测序等技术对559例临床诊断为SCA的患者(363例常染色体显性遗传先证者,196例散发患者)进行了SCA1、SCA2、SCA3/MJD、SCA6、SCA7、SCA8、SCA10、SCA12、SCA17和齿状核-红核-苍白球-路易体萎缩(DRPLA)致病基因多核苷酸病理重复突变检测分析.结果 在363个常染色体显性遗传的SCA(AD-SCA)家系中,发现有15个SCA1家系(4.13%),26个SCA2家系(7.16%),187个SCA3/MJD家系(51.52%),6个SCA6家系(1.65%),7个SCA7家系(1.93%),1个SCA12家系(0.28%)和1个SCA17家系(0.28%),120个SCA家系未明确基因分型(33.06%);在196例散发SCA患者中,发现有2例SCAI患者(1.02%),3例SCA2患者(1.53%),15例SCA3/MJD患者(7.65%),3例SCA6患者(1.53%),173例SCA患者未明确基因分型(88.27%);未发现SCA8、SCA10和DRPLA型患者.结论 在中国汉族人群中SCA3/MJD为最常见的SCA亚型,其次为SCA2、SCA1、SCA7和SCA6,SCA12和SCA17比较少见,SCA8、SCA10和DRPLA罕见,SCA17亚型为国内首次报道.部分AD-SCA家系存在其他致病基因的作用,大部分散发SCA患者除遗传因素外还存在其他致病因素.     

Spinocerebellar ataxia type 6: CAG repeat expansion in α1a voltage-dependent calcium channel gene and clinical variations in japanese population

Autosomal dominant spinocerebellar ataxias (SCAs) are clinically and genetically a heterogeneous group of neurodegenerative disorders. Recently, mild CAG repeat expansion in the α_1A voltage-dependent calcium channel gene has been found to be associated with a type of autosomal dominant SCA (SCA6). We analyzed 98 Japanese families with autosomal dominant SCAs, for whom CAG repeat expansions of the SCA1, SCA2, Machado-Joseph disease/SCA3, and dentatorubral-pallidoluysian atrophy genes were excluded, and 5 apparently sporadic cases of cortical cerebellar atrophy. The diagnosis of SCA6 was confirmed in 30 families (31%) comprising 47 affected individuals and 1 sporadic case. The size of expanded CAG repeats ranged from 21 to 26 repeat units and was found to be correlated inversely with age at onset. We identified 2 SCA6 patients homozygous for expanded CAG repeats, whose ages at onset were earlier than the 95% lower confidence level, suggesting the presence of a gene dosage effect of expanded CAG repeat. Ataxia is the most common initial symptom found in 45 of the 48 patients. Patients with a prolonged disease course showed other accompanying clinical features including dystonic postures, involuntary movements, and abnormalities in tendon reflexes.     

中国南方汉族健康人TATA结合蛋白基因三核苷酸重复变异研究

目的 研究中国大陆脊髓小脑性共济失调（spinocerebellar ataxias,SCA）17型（SCA17）的分布频率,以及南方汉族健康人群TATA结合蛋白（TATA-binding protein,TBP）基因CAG/CAA重复次数正常变异范围.方法 应用荧光聚合酶链反应（PCR）、毛细管电泳等技术,对已经排除了SCA1、2、3、6、7和齿状核-红核-苍白球路易体萎缩的67个常染色体显性遗传SCA家系的先证者、66例散发SCA患者及110名健康人进行TBP基因CAG/CAA重复次数分析.结果 南方汉族健康人群TBP基因CAG/CAA重复次数范围为26～43次,杂合频率为76.36%,共有14种等位基因.在一个散发SCA患者中发现TBP基因CAG/CAA重复次数为44次.结论 SCA17在中国内地为罕见的SCA亚型,南方汉族健康人群TBP基因常见的CAG/CAA重复次数为34和35次.     

广东汉族人遗传性脊髓小脑型共济失调基因突变的研究

目的 研究广东汉族人遗传性脊髓小脑型共济失调（SCA）的亚型（SCA1、SCA2、SCA3和SCA7）基因突变分布频率。方法 对临床诊断为SCA的18个家系24例SCA患者、22例散发SCA患者、45名家系“正常人”及30名非家系健康人,通过聚合酶链反应（PCR）及聚丙烯酰胺凝胶电泳（PAGE）等技术检测SCA1、2、3、7基因内CAG三核苷酸重复序列突变,并利用ABI310、377测序仪对异常等位基因片段进行DNA测序。结果 在18个SCA家系中,1个家系（5.55％）有SCA1基因突变,2个家系（11.11％）有SCA2基因突变,7个家系（38.88％）有SCA3基因突变,未发现SCA7突变,。在家系成员中检出1例症状前SCA3患者。22例散发性患者中检出SCA1、SCA2、SCA3和SCA7各1例,各占4.54％。SCA1患者CAG重复数为53～56次,正常人19～34次;SCA2患者CAG重复数为38～45次,正常人20～25次;SCA3患者CAG重复数为74～81次,正常人14～40次。SCA7患者CAG重复数为65次,正常人为9～19次。结论 提示中国人SCA主要为SCA3/MJD型,其次为SCA2和SCA1。基因分析对家族性以及散发性SCA患者的临床确诊和遗传咨询均有重要意义。     

CAG repeat expansions in patients with sporadic cerebellar ataxia

CAG repeat expansions cause spinocerebellar ataxia type 1 (SCA1), SCA2, SCA3, SCA6 and dentatorubral-pallidoluysian atrophy (DRPLA). So far these expansions have been examined mainly in ataxia patients with a family history. However, some sporadic cases with SCA have recently been reported. To elucidate the frequency and characteristics of sporadic SCAs, we screened 85 Japanese ataxia patients without a family history for the SCA1, SCA2, SCA3, SCA6 and DRPLA mutations. As a result, 19 patients (22%) were found to have expanded CAG repeats. Among sporadic SCAs, the SCA6 mutation was most frequently observed. The sporadic SCA6 patients had smaller CAG repeats and a later age of onset than SCA6 patients with an established family history. We also identified one father-child pair in which intermediate sized CAG repeats expanded into the SCA2 disease range during transmission. These findings suggest that patients with ataxia even without a family history should be examined for a CAG repeat expansion.