脊髓小脑性共济失调12型维吾尔族一家系的基因突变及临床特点

目的 研究新疆地区维吾尔族脊髓小脑性共济失调12亚型(spinocerebellar ataxia type 12,SCA12)致病基因的CAG三核苷酸病理重复次数范围及临床特点.方法 依据Harding标准,收集一个维吾尔族家系,应用聚合酶链反应、琼脂糖凝胶电泳、T载体分子克隆技术并结合酶切鉴定、直接测序等技术对其中6例患者、54例家系"健康"个体进行分子遗传学诊断,基因诊断为SCA12型,同时对致病基因CAG三核苷酸病理重复次数进行突变分析.结果 发现该家系SCA12型患者6例,症状前患者13例.5例经基因重组检测发现:患者异常等位基因CAG重复数目分别是47次、51次、52次、53次;症状前患者是48次;其中在连续CAG重复中间有单个碱基C、A、G的互相替换.结论 SCA12型的47次CAG病理重复次数为国内外报道的最小CAG病理重复次数;国内首次对维吾尔族SCA12型的基因突变特点进行分析,从而对于该类疾病的准确分类、病因探讨、治疗、产前诊断等具有重要的意义.

Abstract：

Objective To investigate the CAG trinucleotide repeat expansion and clinical characteristics of a Chinese Uygur family with spinocerebellar ataxia type 12 (SCA12) in Xinjiang Uygur Autonomous Region. Methods In the Uygur SCA12 family, 6 patients and 54 "healthy" members were analyzed by polymerase chain reaction, agarose gel electrophoresis, recombinant DNA technology by T-Vector cloning and restriction enzyme digestion, and direct sequencing. The diagnosis of SCA12 was confirmed. The CAG trinucleotide expansion was also analyzed. Results Six members in the family were diagnosed as SCA12 patients and 13 were presymptomatic. Five of them were successfully detected by sequencing. The CAGrepeat numbers of 4 patients were 47, 51, 52 and 53, respectively, and 48 in the presymptomatic patient.We also observed that in the CAG repeat region there was replacement of single nucleotide C, A or G.Conclusion Forty-seven CAG repeats of SCA12 has been reported as the shortest known causative expanded alleles. The present study is the first report of the characteristics of SCA12 gene mutation in Chinese. It will provide basis for the accurate classification, disease etiology, treatment and prenatal diagnosis of this disease.     

脊髓小脑性共济失调12型维吾尔族一家系的基因突变及临床特点

目的 研究新疆地区维吾尔族脊髓小脑性共济失调12亚型(spinocerebellar ataxia type 12,SCA12)致病基因的CAG三核苷酸病理重复次数范围及临床特点.方法 依据Harding标准,收集一个维吾尔族家系,应用聚合酶链反应、琼脂糖凝胶电泳、T载体分子克隆技术并结合酶切鉴定、直接测序等技术对其中6例患者、54例家系"健康"个体进行分子遗传学诊断,基因诊断为SCA12型,同时对致病基因CAG三核苷酸病理重复次数进行突变分析.结果 发现该家系SCA12型患者6例,症状前患者13例.5例经基因重组检测发现:患者异常等位基因CAG重复数目分别是47次、51次、52次、53次;症状前患者是48次;其中在连续CAG重复中间有单个碱基C、A、G的互相替换.结论 SCA12型的47次CAG病理重复次数为国内外报道的最小CAG病理重复次数;国内首次对维吾尔族SCA12型的基因突变特点进行分析,从而对于该类疾病的准确分类、病因探讨、治疗、产前诊断等具有重要的意义.     

脊髓小脑性共济失调一家系的基因诊断和产前诊断

目的 确定一脊髓小脑性共济失调(spinocerehellar ataxia,SCA)家系具体分型,并开展症状前患者检测和产前诊断.方法 收集该脊髓小脑性共济失调家系中的2例患者的血液标本,结合该家系的临床表现和我国该类疾病的发病率,采用聚合酶链反应对SCA1、SCA2和SCA3/MJD 3个基因的三核苷酸重复片段进行扩增,并通过琼脂糖凝胶电泳和PCR产物测序的方法确定所有正常和异常扩增等位基因内三核苷酸重复次数.明确致病基因后,对患者子女进行症状前检测,并对1例怀孕症状前患者进行了产前诊断.结果 SCA1和SCA2基因内三核苷酸重复次数在正常范围内,SCA3/MJD的2个等位基因中1个等位基因三核苷酸重复次数在正常范围内,另1个等位基因三核苷酸重复次数在异常范围内.患者子女有1人携带异常等位基因,胎儿携带异常等位基因.结论 该家系经基因诊断确诊为SCA3/MJD型,有1人为症状前患者,该症状前患者所孕胎儿也为症状前患者.     

浙江沿海一家系脊髓小脑性共济失调的基因突变检测与临床表现

目的 探讨浙江沿海脊髓小脑性共济失调的基因突变检测与临床表现.方法 对该家系18例患者的临床表现、头颅MRI等辅助检查资料分析,并与10名家系中未发病成员及12名非血缘的健康人进行SCA31MJD基因CAG三核苷酸重复数目比较.结果 家系18例患者均为SCA3/MJD型,同时检测出家系中未发病对照组有2例为SCA31MJD型基因携带者.产物测序结果家系对照组与健康对照组CAG重复数为14～27次;SCA患者CAG重复数为67～82次;SCA3/MJD携带者CAG重复数为28～45次.在现存三代18例患者中,每代均有患者,男女均受累,起病年龄平均38岁,以行走不稳、动作笨拙和言语含糊为突出表现,MRI检测结果小脑、脑干明显萎缩.结论 在我国沿海存在SCA3/MJD家系遗传.临床均以共济失调和构音障碍为突出,CAG重复数目检测可为基因诊断和症状前诊断提供依据.     

脊髓小脑性共济失调的分子遗传学研究进展

脊髓小脑性共济失调是一类单基因常染色体显性遗传病,不同的基因突变将导致不同的遗传亚型。随着分子遗传学技术的飞速发展,目前已经获得基因定位的有近30种亚型,多数是由于三核苷酸重复序列异常扩增引起,其中部分亚型的致病基因已被克隆。本文主要就新近发现的几种亚型作简要综述。     

一个遗传性脊髓小脑型共济失调大家系的致病基因分析

目的探讨一个遗传性脊髓小脑型共济失调（SCA）大家系的遗传特点和基因突变分析。方法对一个遗传性脊髓小脑型共济失调（SCA）大家系进行家系调查,绘制系谱图,抽取家系成员外周血,采用聚合酶链反应和毛细管电泳对致病基因进行分析检测。结果该家系的遗传性脊髓小脑型共济失调（SCA）为常染色体显性遗传,6代45人中有15人为SCA患者,4人为携带致病基因的无症状患者。患者ATX3基因的CAG三核苷酸重复65-73次。结论该家系为常染色体显性遗传的SCA3型（SCA/MJD）,患者基因突变检测分析显示异常扩增的CAG突变数与发病年龄呈明显的负相关。基因突变检测在疾病诊断和早期发现无症状患者方面有重要作用,从遗传生殖角度阻断该病的遗传有重要意义。     

脊髓小脑性共济失调一家系11例

先证者 (Ⅳ5)　男 ,2 9岁。因双下肢无力、行走不稳进行性加重伴言语不清 7年入我院神经科。患者于 7年前无明显诱因渐出现双下肢无力 ,行走不稳、左右摇摆、易跌倒 ,且呈进行性加重 ,并逐渐出现双下肢震颤 ,讲话慢、费力、言语含糊不清。无头晕、头痛及恶心、呕吐 ,无吞咽障碍。查体 :神清 ,表情呆滞 ,反应迟钝 ,言语费力、含糊不清 ,双眼球水平震颤阳性 ,咽反射正常 ,双上肢肌力、肌张力正常 ,双手轻度意向性震颤 ,精细动作笨拙 ,双下肢肌肉轻度萎缩 ,肌张力高 ,肌力基本正常 ,感觉正常 ,双上肢腱反射正常 ,双下肢腱反射亢进 ,踝震挛阳性 …     

辽宁地区脊髓小脑性共济失调一大家系分子遗传学研究

目的研究一脊髓小脑性共济失调大家系的基因分型。方法收集该脊髓小脑性共济失调大家系中的13名患者的血液标本,结合该家系的临床表现和我国该类疾病的发病率,采用聚合酶链反应对SCA1、SCA2和SCA3/MJD三个基因的三核苷酸重复片段进行扩增,并通过琼脂糖凝胶电泳和PCR产物测序的方法确定所有正常和异常扩增等位基因内三核苷酸重复次数。结果 SCA1和SCA2基因内三核苷酸重复次数在正常范围内,SCA3/MJD的两个等位基因中一个等位基因三核苷酸重复次数在正常范围内,另一个等位基因三核苷酸重复次数在异常范围内。结论该家系经基因诊断确诊为SCA3/MJD型。     

脊髓小脑性共济失调的分子遗传学进展

脊髓小脑性共济失调是一类由于遗传因素造成的单基因神经系统变性性疾病 ,不同位点的三核苷酸重复扩增导致不同的遗传亚型。已经发现 2 2种亚型的脊髓小脑性共济失调 ,多数是由于致病基因内存在 CAG重复片段异常扩增 ,导致含有多聚谷氨酰胺链的突变蛋白在细胞核内沉积形成核内包涵体。本文就其最近的分子遗传学进展作简要综述     

遗传性脊髓小脑型共济失调的CAG三核苷酸突变检测

目的 评价ＳＣＡ１、ＳＣＡ２、ＳＣＡ３／ＭｊＤ、ＳＣＡ６、ＳＣＡ７和ＤＲＰＬＡ的ＣＡＧ三核苷酸异常扩增突变「（ＣＡＧ）ｎ」,在中国人遗传性脊髓小脑型共济失调（ｓｐｉｎｏｃｅｒｅｂｅｌｌａｒ ａｔａｘｉａ,ＳＣＡ）患者的分布频率。方法 经聚合酶链反应、变性聚丙烯酰按凝胶电泳和银染显带技术,检测分析了８５个中国人常染色体显性遗传ＳＣＡ家系（其中患者１６７例）和３７例散发ＳＣＡ患者的ＳＣＡ１、ＳＣＡ２、     

一个遗传性共济失调7型家系的基因突变分析

目的 研究1个遗传性共济失调7型回族家系的临床表现与基因突变特点.方法 应用聚合酶链反应、分子克隆及测序等方法对1个临床诊断为遗传性共济失调的回族家系进行SCA7基因检测,对异常片段进行分子克隆测序.结果 证实该家系为遗传性共济失调7型家系,视网膜退行性变为其相对独特的临床表现.先证者父亲异常片段CAG重复为46次;先证者异常片段CAG重复次数为54次,发病年龄较父代提前22年.结论 报告1个遗传性共济失调7型回族家系,该亚型明显的遗传早现及病程进展与CAG重复次数的不稳定扩增相关.     

脊髓小脑性共济失调3型线粒体DNA突变的研究

目的 探索脊髓小脑性共济失调3型(spinocerebellar ataxia type 3,SCA3)与线粒体DNA(mitochondrial DNA,mtDNA)突变的关系.方法 采用测序方法对临床诊断为脊髓小脑性共济失调的患者及家系成员行MJD1基因CAG重复拷贝数检测,以基因水平确诊SCA3患者及症状前患者.然后采用聚合酶链反应、单链构象多态性分析、测序方法对基因确诊的43例SCA3患者及症状前患者和30名对照组的mtDNA片段进行分析.结果 发现SCA3组4名成员存在mtDNA位点8282.8290区域9个碱基缺失.结论 在SCA3患者及症状前患者中发现mtDNA缺失突变的现象.     

Whole exome sequencing identifies a novel mutation in the transglutaminase 6 gene for spinocerebellar ataxia in a Chinese family

Li M, Pang SYY, Song Y, Kung MHW, Ho S‐L, Sham P‐C. Whole exome sequencing identifies a novel mutation in the transglutaminase 6 gene for spinocerebellar ataxia in a Chinese family. Autosomal dominant spinocerebellar ataxias (SCA) constitute a heterogeneous group of inherited disorders. The transglutaminase 6 (TGM6) gene was recently suggested as a SCA causative gene in Chinese SCA families. In this study, two affected members of a three‐generation Chinese family with SCA characterized by progressive cerebellar ataxia and lower limb pyramidal signs were subjected to whole exome sequencing. Through bioinformatics analysis of the sequence variants in these two individuals, we identified a novel mutation in the TGM6 gene (c.1528G>C) which showed perfect co‐segregation with disease phenotype in all nine members of this family. This finding confirms that mutations in TGM6 gene represent an important cause of SCA in Chinese. This study also shows that whole exome sequencing of a small number of affected individuals, leveraged on bioinformatics analysis, can be an efficient strategy for identifying causative mutations in rare Mendelian disorders.     

脊髓小脑共济失调患者CAG病理重复次数检测

目的 研究中国汉族人群脊髓小脑性共济失调(spinocerebellar ataxia,SCA)1、2、3、6、7、12、17亚型致病基因的CAG三核苷酸病理重复次数范围.方法 应用聚合酶链反应、琼脂糖凝胶电泳、T载体克隆重组DNA技术并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SCA1、SCA2、SCA3/马查多-约瑟夫病(Machado-Joseph disease,MJD)、SCA6、SCA7、SCA12和SCA17致病基因CAG三核苷酸病理重复次数突变分析.结果 在559例SCA患者中,共检测出SCA1患者23例,CAG病理重复次数范围39～60次,平均(51.09±4.88)次;SCA2患者32例,CAG病理重复次数范围36～51次,平均(40.34±4.40)次;SCA3/MJD患者305例,CAG病理重复次数范围49～86次,平均(73.84±5.07)次;SCA6患者9例,CAG病理重复次数范围23～29次,平均(25.56±1.94)次;SCA7患者27例,CAG病理重复次数范围38～71次,平均(58.22±10.90)次;SCA12患者3例,CAG病理重复次数范围51～52次,平均(51.33±0.58)次;SCA17患者2例,CAG病理重复次数范围53～55次,平均(54.00±1.41)次.结论 SCA1的39次CAG病理重复、SCA3/MJD的49次CAG病理重复和SCA12的51次CAG病理重复为国内或国外报道的最小CAG病理重复次数;SCA3/MJD的86次CAG病理重复为国内外报道的最大CAG病理重复次数;SCA17为国内首次发现的SCA亚型;首次建立中国汉族人群不同SCA亚型CAG三核苷酸病理重复次数范围标准.     

Genetic and clinical analysis in a Chinese parkinsonism-predominant spinocerebellar ataxia type 2 family

Parkinson's disease is a degenerative central nervous system disorder that often impairs motor skills, speech and other functions. We discovered a large Chinese family showing primarily parkinsonism symptoms with autosomal dominant inheritance. Six affected individuals in the family showed typical parkinsonism symptoms, including pill-rolling tremor. Two other affected individuals showed cerebellar ataxia symptoms. A whole-genome scan using the 50K single nucleotide polymorphism array with three different linkage methods detected two positive regions on chromosome 12q24.1 and 5q13.3. The ATXN2 gene, responsible for spinocerebellar ataxia type 2 (SCA2) was located precisely in the center of the positive region on chromosome 12. Further analysis of SCA2 revealed heterozygous pathological CAG expansions in the family. The affected individuals' symptoms were typical of parkinsonism, but complex. Inverse correlation between CAG repeat size and age of onset is not obvious in this pedigree. This parkinsonism-predominant SCA2 family shared the same disease gene locus with other 'standard' SCA2 families, but it is possible that variations in one or more modifier genes might account for the parkinsonism-predominant SCA2 predisposition observed in this pedigree.     

中国大陆汉族人群SCA各亚型的突变频率分析及SCA6的临床和分子特征

目的评价中国大陆汉族人群常染色体显性遗传脊髓小脑型共济失调(spinocerebellar ataxla．SCA)各亚型包括SCA1、SCA2、SCA3／Machado-Joseph病(Machado—Joseph disease,MJD)、SCA6、SCA7、SCAB、SCA10、SCA12、SCA14、SCA17和齿状核红核苍白球路易氏体萎缩症(dentatorubro—pallidoluysian atrophy，DRPLA)的突变频率，并总结SCA6的临床和分子特征。方法对中国大陆120个常染色体显性遗传SCA家系和60例散发性SCA患者进行突变分析，并总结了4个SCA6家系13例患者的临床和分子特征。结果SCA3／MJD是中国大陆汉族人群中最常见的SCA亚型，共发现59个家系83例患者(阳性率49．2％)．其次还发现8个SCA2家系(6．7％)、7个SCA1家系(5．8％)、4个SCA6家系(3．3％)、1个SCA7家系(0．8％)，未发现SCA8、SCA10、SCA12、SCA14、SCA17和DRPLA家系。有41个SCA家系(34．2％)不能进行基因分型。在60例散发性SCA患者中，有3例为SCA3基因突变，未发现有SCA6基因突变。4个SCA6家系有明显的遗传早现，但在代间传递过程中无遗传不稳定现象。结论首次在中国大陆汉族人群报道了SCA6亚型的突变频率。