脊髓小脑共济失调7型一个家系的临床和基因分析

目的总结脊髓小脑共济失调7型（SCA7）的临床表现，开展基因检测。方法对1个表现为视力下降、辨色力异常和行走不稳的家系完成家系调查及体格检查，部分成员行视网膜形态学及电生理检查；19名家系成员及12名健康对照者行SCA7突变基因PCR，测序仪直接检测三核苷酸胞嘧啶-腺嘌呤-鸟嘌呤（CAG）重复数目。结果6例成员存在小脑性共济失调、视力下降和辨色力异常，眼底示黄斑及视网膜周边色素异常，视网膜电图波形熄灭，震荡电位幅值和光闪视觉诱发电位振幅明显下降；正常等位基因CAG重复数目为8～25次，该6例异常等位基因CAG重复数目为50～97次，诊断为SCA7患者；1例无异常临床表现的成员CAG重复数目分别为18次和56次，后者超出正常范围，诊断为未到发病年龄的症状前患者。结论SCA7患者的临床表现具有异质性，CAG重复数目检测可以为基因诊断和症状前诊断提供依据。     

脊髓小脑共济失调2型、3型患者10例基因突变与临床表型分析

目的探讨脊髓小脑共济失调（SCA）2型、3型患者的基因突变特点及临床表型。方法总结4个SCAs家系的9例患者和1例散发患者的临床表现，对全部患者、43名家系成员及60名健康对照，采用PCR、荧光PCR、毛细管电泳等技术检测分析SCA2、3基因内CAG三核苷酸重复序列的长度及拷贝数。结果3个家系中的6例患者、1例散发患者存在SCA3／MJD（CAG）n扩展突变，CAG重复数为68—75次；1个家系的3例患者存在SCA2（CAG）n扩展突变，CAG重复数为39—41次。两型患者的临床表现有重叠之处，但在发病年龄、病程进展、神经系统受累部位等方面有明显差异。结论SCA3／MJD型与SCA2型在临床表现上存在一定差异性，有助于鉴别和分型，但基因检测是明确诊断的惟一方法。     

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。     

脊髓小脑共济失调3型家系CAG动态突变分析和产前诊断

目的探讨脊髓小脑共济失调3型患者的临床特点、分子遗传学特征及产前诊断的意义。方法采用聚合酶链反应及DNA片段分析技术对脊髓小脑共济失调3型一家系4代共9例患者（其中1例为先证者之4月龄胎儿）中的2例患者施行SCA3／ATXN3基因（CAG）。重复数目分析。结果一家系中4代共9例患者发病均符合常染色体显性遗传特征,其中8例患者（除外先证者之4月龄胎儿）均以步态不稳为首发症状,伴发不同程度构音障碍;先证者神经系统检查显示共济失调伴眼球上视受限及锥体束损害体征。其中第1代患者于50岁左右发病、第2代患者40～45岁发病、第3代（先证者）28岁发病,发病年龄呈逐代提前现象。先证者SCA3／ATXN3基因（CAG）。重复数目为77次（〉44次）,其4月龄胎儿（CAG）．;重复数目也为77次,通过产前诊断证实亦为脊髓小脑共济失调3型患者。结论脊髓小脑共济失调3型是亚洲人种中最常见的脊髓小脑共济失调亚型,以步态不稳为首发症状,除小脑性共济失调外尚可伴发其他临床表现。家系中存在遗传早现现象,但其CAG动态突变率较小。脊髓小脑共济失调3型病因明确但无有效治疗方法,对患者进行遗传咨询并对其胎儿进行产前诊断,是预防和中断遗传链之关键措施。     

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.     

细胞凋亡在脊髓小脑性共济失调3型发病机制中的作用

目的研究细胞凋亡在脊髓小脑性共济失调3型(SCA3)分子发病机制中的作用。方法将带有SCA3正常与突变基因的增强型绿色荧光蛋白真核表达载体(pEGFP)转染大鼠肾上腺嗜铬细胞瘤(PC12)细胞,采用丫啶橙(AO)染色及电镜观察细胞凋亡的发生情况,免疫荧光检测转染后24h、72h、120h半胱氨酸天门冬氨酸酶3、8(caspase3、8)在细胞核内的分布及其与核内包涵体(INIs)共定位的情况;缺口末端标记(TUNEL)法观察正常基因组与突变基因组以及突变基因组在给予广谱caspase阻断剂zVAD-fmk(100μmol/L)后细胞凋亡的变化。结果随着转染后时间的延长,突变基因组细胞发生了明显的凋亡,caspase3、caspase8核内与INIs共定位。正常组与突变组TUNEL阳性细胞数有明显差异并有显著性意义(P<0.01),突变组在给予zVAD-fmk后细胞凋亡明显减轻,差异有显著性意义(P<0.01)。结论细胞凋亡在SCA3发病机制中起重要的作用,抑制凋亡通路可以减少细胞死亡,推测对凋亡环节的干预有可能成为SCA3治疗的靶点。     

新疆地区脊髓小脑共济失调2型患者临床表型相关分析

目的分析新疆地区脊髓小脑共济失调2型(SCA2)患者临床表型。方法对根据Harding诊断标准考虑为脊髓小脑共济失调(SCAs)的患者进行神经系统查体,通过国际协作共济失调等级评分量表(ICARS)、简易智力状态量表(MMSE)进行共济失调严重程度及认知功能的初步评估。用酚氯仿法提取基因组DNA,采用PCR对患者进行SCAs亚型分型。对1例SCA2患者进行克隆后测序。结果发现了9例SCA2患者。1例SCA2患者测序结果为CAG重复47次。该患者以震颤起病,临床表现主要为帕金森综合征,病程6年,ICARS评分10分。4名患者以步态失调起病,病程在2~4年,ICARS评分在15~26分。结论根据临床表现可初步诊断脊髓小脑共济失调,SCA2临床表现存在异质性,故确定诊断依赖于基因诊断。以帕金森综合征表现为主的SCA2型患者共济失调症状发展较缓慢。     

脊髓小脑性共济失调2型的分子遗传学诊断及临床分析

目的:研究分析脊髓小脑性共济失调2型(SCA2)的分子遗传学诊断、应用以及临床表现特征。方法:对来自广西地区临床诊断为SCA的1个家系2例患者和8名"健康"家系成员,以及35名正常对照人员,通过聚合酶链式反应、琼脂糖电泳等技术检测SCA2基因位点内CAG三核苷酸重复扩增次数,并对异常等位基因片段进行DNA测序。结果:我国广西正常人群SCA2等位基因CAG重复数为20～29次,1家系中2例患者与1例症状前患者存在SCA2(CAG)n扩展突变,拷贝数分别为42、45、55次。结论:首次发现广西SCA2,利用分子遗传学分析可进行SCA2基因诊断,为症状前诊断及遗传咨询提供依据。     

脊髓小脑性共济失调12型一家系的临床特征和基因突变分析

目的研究1个遗传性共济失调12型(spinocerebellar ataxia type 12 SCA12)家系的临床特征与基因突变特点。方法应用聚合酶链反应、毛细管电泳等方法对1个临床诊断为遗传性共济失调的家系进行SCA基因检测。结果确定该家系为遗传性共济失调SCA12型家系。共确诊7例现证患者,患者异常CAG的重复次数为51⁵5次。结论上肢震颤,逐渐出现共济失调、延髓麻痹,病理征阳性为SCA12型相对独特的临床表现。先证者异常片段CAG重复为55次,第3代患者Ⅲ2 CAG重复次数54次,发病年龄提前,可能存在遗传早现现象。SCAs核苷酸突变扩展的数目与年龄呈负相关,与症状严重程度呈正相关的特点可能也存在于SCA12型中。     

基于脐带血和短串联重复序列分析的脊髓小脑共济失调3型产前诊断

目的 探讨脊髓小脑共济失调3型(SCA3)的产前诊断方法 .方法 对1个SCA3家系女性先证者的胎儿进行产前检测,于妊娠20周抽取脐带血进行胎儿DNA提取,采用PCR和基于CEQ8000核酸分析仪的短串联重复序列分析技术进行SCA3基因CAG重复序列动态突变检测.结果 先证者SCA3基因CAG重复数目为31/75次,其配偶CAG重复数目为14/27次,胎儿CAG重复数目为14/31次,其中14次重复来自父亲,31次重复来自母亲的正常等位基因,符合孟德尔遗传规律.本次检测的胎儿携带患者的正常等位基因.胎儿出生后的检测结果 与产前检测完全相同.结论 通过脐带血和短串联重复序列分析技术检测SCA3基因CAG重复序列动态突变,可快速、可靠地进行SCA3产前诊断.     

Tremor-spectrum in spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3) can be present with a combination of cerebellar, neuropathic, pyramidal, or extrapyramidal symptoms. Tremor is a classical but not frequent manifestation of SCA3 and there is a lack of detailed knowledge regarding its origin. To study the clinical and electrophysiological characteristics of tremor in SCA3 patients, the authors conducted a case series of 72 SCA3 patients. Clinical characteristics of tremor and associated signs, response to treatments, follow-up, and genetic results were collected. Electrophysiological study including polymyographic recording was possible in 4/6 patients and DaTSCAN in 2/6. The authors also performed a systematic review of SCA3 cases with tremor (n?=?36) reported previously in the literature. We identified two different tremor-types in 6/72 patients with SCA3 mutations, a “fast” (6.5–8?Hz) action, postural or tremor in orthostatism (initial symptom), which became slower over time with associated parkinsonism with a follow-up of 10?years and a “slow” rest, action and intention tremor (3–4?Hz) with distal and proximal component (including axial tremor in orthostatism). Total improvement of limbs and tremor in orthostatism was obtained with levodopa with occurrence of fluctuations/dyskinesia. Partial benefit was observed when additional signs were present (myoclunus/dystonia). The differences in tremor subtypes in SCA3 may be related to various combinations of mild to severe dysfunctions of the cerebello-thalamo-cortical loop and the nigro-striatal dopaminergic pathway.     

Axonal inclusions in spinocerebellar ataxia type 3

Protein aggregation is a major pathological hallmark of many neurodegenerative disorders including polyglutamine diseases. Aggregation of the mutated form of the disease protein ataxin-3 into neuronal nuclear inclusions is well described in the polyglutamine disorder spinocerebellar ataxia type 3 (SCA3 or Machado–Joseph disease), although these inclusions are not thought to be directly pathogenic. Neuropil aggregates have not yet been described in SCA3. We performed a systematic immunohistochemical study of serial thick sections through brains of seven clinically diagnosed and genetically confirmed SCA3 patients. Using antibodies against ataxin-3, p62, ubiquitin, the polyglutamine marker 1C2 as well as TDP-43, we analyzed neuronal localization, composition and distribution of aggregates within SCA3 brains. The analysis revealed widespread axonal aggregates in fiber tracts known to undergo neurodegeneration in SCA3. Similar to neuronal nuclear inclusions, the axonal aggregates were ubiquitinated and immunopositive for the proteasome and autophagy associated shuttle protein p62, indicating involvement of neuronal protein quality control mechanisms. Rare TDP-43 positive axonal inclusions were also observed. Based on the correlation between affected fiber tracts and degenerating neuronal nuclei, we hypothesize that these novel axonal inclusions may be detrimental to axonal transport mechanisms and thereby contribute to degeneration of nerve cells in SCA3.     

Homozygosity enhances severity in spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3, or Machado-Joseph disease, is an autosomal dominant neurodegenerative disease characterized by a wide spectrum of clinical findings that include progressive cerebellar ataxia. All affected individuals have an expanded CAG repeat mutation in one allele of the ATXN3 gene. An inverse relationship exists between the age of onset and the number of repeats in the abnormal expanded allele. The case described is that of a child with Machado-Joseph disease, daughter of a consanguineous affected couple. She inherited the expanded allele in homozygosity with CAG repeat size similar to that of her parents, and had a distinct early onset (4 years of age) and severe clinical phenotype. This case supports the conclusion that homozygosity aggravates the clinical phenotype. Loss of function of the normal expressed ataxin-3, or possibly aggregation of ataxin-3, may be implicated in disease mechanism.     

Analysis of diffusion tensor parameters in spinocerebellar ataxia type 3 and type 10 patients

IntroductionThere is a dearth of studies of spinocerebellar ataxias (SCAs) and diffusion tensor magnetic resonance imaging (DTI).ObjectiveTo analyze changes observed in DTI parameters and correlate these to clinical findings in SCA3 and SCA10 patients.MethodsSCA3 (n = 19) and SCA10 (n = 18) patients were compared with a similar number of controls and assessed clinically and with the scale for the assessment and rating of ataxia (SARA) before undergoing the same MRI protocol. TRACULA (TRActs Constrained by UnderLying Anatomy) software was used to analyze the DTI metrics FA, AD, RD and MD.ResultsMore white matter fiber tracts with changes in diffusivity were found in SCA3 patients than in SCA10 patients. There was a reduction in AD in altered fiber tracts in SCA3 and a greater increase in RD in SCA10. In the SCA3 patients, FA was reduced in the corticospinal tract (CST) and inferior longitudinal fasciculus (ILF), but this was not observed in the SCA10 patients. SARA score was correlated with DTI findings in SCA3 but not in SCA10.ConclusionChanges were observed in DTI for both SCA3 and SCA10 but were more widespread in SCA3. Our finding of myelin-sheath changes in SCA10 and secondary axonal changes in SCA3 may reflect the more rapid, aggressive clinical course of SCA3.     

Executive dysfunction in patients with spinocerebellar ataxia type 3

The aim of this study was to assess the cognitive functions of patients with spinocerebellar ataxia type 3(SCA3). We examined 15 patients with genetically confirmed SCA3 and 15 healthy control subjects matched for age, years of education, and intellectual ability. We administered verbal memory (word recall and word recognition) and executive function tasks (word fluency test, forward and backward digit and visual span tests, Kana Pick-out Test, Trail Making Test, and conflicting instructions and a Go/NoGo task from the Frontal Assessment Battery). We found that patients with SCA3 had significantly lower scores than the healthy control subjects on the word recall, semantic, and letter fluency, and backward digit span tests, while word recognition was well preserved. The other executive function tests showed preserved functions in the SCA3 group, indicating that visual working memory, and attention and inhibition control were not affected. The patients with SCA3 showed impaired word recall and intact word recognition, and accordingly, episodic memory encoding and storage processes in short-term memory were preserved. In category and letter-fluency tests, impairment was attributable to word-retrieval from semantic memory. Impaired verbal working memory may be involved in the retrieval of verbal information from phonological storage by means of continuous subvocal rehearsal, rather than a deficit in initial phonological encoding. Essential executive dysfunction in patients with SCA3 may be due to damage in the cerebellar cortex–ventral dentate nucleus–thalamus–prefrontal cortex circuits, which are involved in strategic retrieval of verbal information from different modes of memory storage.