疑似脊髓性肌萎缩症患儿338例的运动神经元存活基因分析

目的 研究儿童脊髓性肌萎缩症(SMA)运动神经元存活基因SMN1缺失和诊断的意义.方法 根据国际诊断标准、病例随访和基因分析结果对338例疑似SMA的患儿进行诊断和分型.应用PCR-酶切方法分析患儿SMN1基因外显子7和外显子8的纯合缺失.应用等位基因特异PCR结合变性高效液相色谱分析(DHPLC)方法分析患儿的SMN1基因拷贝数,确定杂合缺失.结果 (1)确诊SMA 267例,其中Ⅰ型143例,Ⅱ型82例,Ⅲ型42例,分别占53.6%、30.7%和15.7%.(2)267例SMA患儿的SMN1基因缺失分析显示:SMN1基因外显子7和8均纯合缺失为183例,占68.5%(183/267),仅外显子7纯合缺失,外显子8不缺失为34例,占12.7%(34/267),外显子7杂合缺失为33例,占12.4%(33/267),非缺失为17例,占6.4%(17/267),未见SMN1基因外显子8的单独缺失.(3)Ⅰ型和Ⅱ型SMN1基因缺失率相近.Ⅲ型SMN1基因纯合缺失率较低于Ⅰ型和Ⅱ型,杂合缺失率较高于Ⅰ型和Ⅱ型.结论 (1)我国儿童SMA的SMN1基因纯合缺失和杂合缺失频率提示,SMN1基因突变存在种族异质性,SMN1基因内微小突变需要研究.(2)SMN1基因诊断具有特异性和无创性,80%SMA患儿通过SMN1基因纯合缺失分析得到诊断.(3)Ⅲ型SMA的临床诊断和基因分析需要进一步研究.     

脊髓性肌萎缩症SMN1和SMN2基因拷贝数变异分析

目的:探讨运动神经元存活（SMN）1和SMN2基因拷贝数变异与脊髓性肌萎缩症（SMA）患儿临床表型的关系。方法:以2011年10月至2012年12月在复旦大学附属儿科医院临床诊断SMA患儿为研究对象,采用基因组DNA多重连接探针扩增（MLPA）技术进行SMN1基因缺失和SMN2基因拷贝数变异检测,探讨拷贝数变异与SMA临床分型的关系。结果:41例临床诊断SMA患儿行基因检测,其中SMN1基因第7和（或）8外显子缺失37例（90.2％）进入分析,男女之比为1∶0.8,发病年龄为（7.5±7.0）个月。Ⅰ型20例（54.1％）,Ⅱ型15例（40.5％）,Ⅲ型2例（5.4％）,发病年龄分别为（2.9±1.8）、（10.7±1.9）和（30.0±8.5)个月。37例SMN1基因第7和（或）8外显子缺失患儿中,18例SMN2基因第7和8外显子拷贝数为2个,其中13例（72.2％）为Ⅰ型,5例（27.8％）为Ⅱ型;19例SMN2基因第7和8外显子拷贝数增加（拷贝数3或4）,其中7例（36.8％）为Ⅰ型,10例（52.6％）为Ⅱ型,2例（10.5％）为Ⅲ型,两组差异有统计学意义。5例患儿父母行SMN1基因检测,共检出杂合缺失9例,其中4例患儿父母均为SMN1基因第7和8外显子杂合缺失,1例患儿父亲为SMN1基因第7和8外显子杂合缺失,母亲未检测到纯合或杂合缺失。结论:SMN1基因第7和（或）8外显子纯合缺失是SMA致病主要原因,SMN2基因拷贝数增加与SMA表型严重程度呈负相关。     

聚合酶链反应-单链构象多态性和限制性酶切分析法对脊髓性肌萎缩症的基因诊断

目的 对脊髓性肌萎缩症（SMA）的早期诊断提供基因学特征和可靠的辅助检测手段。方法 用PCR-单链构象多态性(SSCP)和PCR-限制性酶切分析法对首都儿科研究所附属儿童医院神经科门诊的30个SMA家系和50名入托查体正常儿童运动神经元存活基因(SMN)的第7和8外显子进行缺失检测。结果 SMN基因外显子7和8缺失检测结果：在30例SMA患儿中，22例（73.3%，22/30）同时缺失SMN1基因外显子7和外显子8，4例（13.3%，4/30）显示单纯SMN1基因外显子7纯合缺失，4例（13.3%，4/30）SMN1基因外显子7或8均未见缺失，未见单纯SMN1基因外显子8纯合缺失。1例SMAⅠ型患儿父亲为SMN1基因外显子7和8的纯合缺失。1名正常儿童有SMN2基因外显子7和8的纯合缺失。经过PCR 限制性酶切法检测不伴有缺失的2例SMA Ⅲ型患儿及其家系SMN1基因外显子8 SSCP电泳图中出现了异常条带。结论 PCR-限制性酶切和PCR-SSCP分析法对SMN1基因外显子7和8缺失进行检测是诊断SMA的有效辅助手段,两者联合应用可以相互验证、互为补充；SMN1基因外显子7或8的缺失检测对SMA进行基因诊断是一种简便、特异的诊断方法，并且由于其为一种无创性检查，易被家长接受，是SMA临床症状前诊断、鉴别诊断和临床确诊的重要辅助手段。     

中国脊髓性肌萎缩症患儿的SMN基因学研究

目的：明确中国人各型脊髓性肌萎缩症(SMA)患儿SMN1基因外显子7和8缺失,SMN基因转变及微小突变情况。方法：对106例患者,采用PCR-RFLP检测基因缺失,RFLP筛查基因转变,并对PCR产物进行测序分析。基因转变率比较采用Fisher精确检验法进行统计学分析。结果：SMA患儿纯合SMN1外显子7和/或8缺失比率为91.5%,发现1例SMA中存在SMN1外显子7保留,而SMN1非编码外显子8缺失。在SMN1外显子7缺失而无外显子8缺失的患者中,各型间基因转变率差别无统计学意义,在SMN1外显子7缺失的SMA中,其基因转变率为8.3%。SMN第7外显子附近未发现基因微小突变。结论：SMN1基因外显子7和/或8缺失为中国SMA患儿的主要病因。SMA中存在SMN基因转变现象。SMN1基因外显子8的单独缺失可能致病。SMN1基因外显子7附近可能不是此病微小突变的热点区域。［中国当代儿科杂志,2010,12（7）：539-543］     

儿童脊髓性肌萎缩症的基因诊断

目的探讨儿童脊髓性肌萎缩症(SMA)的特异性基因诊断方法。方法应用聚合酶链反应-限制性片段长度多态性(PCR—RFLP)技术.对19例临床诊断为SMA患儿及21名健康儿童的运动神经元存活(SMN)基因进行检测。结果SMA患儿SMN基因的第7和第8号外显子均缺失,健康儿童SMN基因的第7和第8号外显子均未缺失。结论检测SMN基因第7和第8号外显子缺失的方法可用于SMA的基因诊断,且PCR—RFLP技术对SMA的诊断具有较高的特异性和敏感性。     

脊髓性肌萎缩症患儿SMN1和SMN2基因拷贝数与临床表型的相关性分析

目的 对脊髓性肌萎缩症（SMA）患儿的运动神经元存活基因1（SMN1）和SMN2拷贝数与临床表型之间的关系进行分析,提高对SMA患儿的早期诊断和临床干预水平。方法 选取45例SMA患儿,应用多重连接依赖性探针扩增技术对SMN1和SMN2基因拷贝数进行检测,分析SMN基因拷贝数同临床表型之间的关系。结果 45例SMA患儿中,SMN1第7和8外显子纯合缺失者为42例,占93%（42/45）;仅有第7外显子缺失者为3例,占7%（3/45）。SMA不同临床分型和SMN1基因第7、8外显子缺失类型间无相关性（P > 0.05）;SMA患儿和健康儿童的SMN2基因拷贝数分布差异有统计学意义（P < 0.05）,前者以2和3拷贝者居多,后者以1和2拷贝者居多;不同SMA临床分型间SMN2拷贝数分布差异有统计学意义（P < 0.05）,SMN2基因为2拷贝者发病年龄明显小于3和4拷贝者。Ⅰ型SMA患儿中SMN2拷贝数以2或3拷贝者居多,Ⅱ型以3拷贝者居多,Ⅲ型以3或4拷贝者居多。随着SMN2拷贝数增加,患儿发病年龄越大,保有的运动功能和临床结局越好,SMN2基因拷贝数同临床结局间的关系存在显著性差异（P < 0.05）。结论 SMN2基因通过剂量补偿效应减轻SMA疾病严重程度,SMN2拷贝数同SMA临床表型具有相关性,可将其作为预测疾病严重程度的依据之一。     

85例脊肌萎缩症疑诊患儿的基因诊断和临床再评估

目的 确定运动神经元存活基因1(survival motor neuron gene 1,SMN1)纯合缺失在中国脊肌萎缩症(spinal muscular atrophy,SMA)患儿中的发生频率,判断SMN1基因纯合缺失检测在中国SMA患儿诊断中的临床价值,探讨基因检测后的临床回访在SMA疑诊患儿临床诊疗中的作用.方法 使用多聚酶链反应和限制性片段长度多态性的方法 (polymerase chain reaction and restriction fragment length polymorphism,PCR-RFLP)对85例临床疑诊SMA的患儿样本进行SMN1基因7号外显子纯合缺失检测.由小儿神经专科医师对SMA患儿进行分型,并对基因检测阴性的患儿依照SMA的诊断标准,必要时结合组织学病理检查进行临床再评估.结果 在85例中,57例(67%)检出SMN1纯合缺失.在19例随访的基因检测阴性患儿中,15例不符合SMA的诊断,4例可维持SMA的诊断.在确诊的SMA患儿中,SMN1纯合缺失率为95%.Ⅰ、Ⅱ、Ⅲ型SMA患儿的SMN1纯合缺失检出率分别为96%、93%和100%,SMA临床分型与SMN1纯合缺失率无显著相关性.结论 中国SMA患儿中SMN1基因纯合缺失约为95%,与高加索人群数据相似.SMN1纯合缺失检测应成为中国SMA疑诊患儿的首选诊断和排除诊断方法 .SMN1纯合缺失检测后患儿的临床回访对SMA疑诊患儿的临床诊疗具有重要意义.     

等位基因特异性扩增法检测脊髓性肌萎缩运动神经元生存基因缺失

目的：用单链构象多态性(SSCP)、限制性片段长度多态(RFLP)的方法诊断脊髓性肌萎缩(SMA)较普遍,但方法复杂。该文采用等位基因特异性扩增法进行SMA基因诊断,以探讨该方法的实用性和特异性。方法：应用等位基因特异性扩增法对40名SMA患者(Ⅰ型15例,Ⅱ型17例,Ⅲ型8例)和40名正常对照进行运动神经元生存基因(SMN)基因外显子7的基因缺失研究。所有SMA患者均经RFLP方法证实缺失SMN1基因外显子7。结果：等位基因特异性扩增法检测所有SMA患者均存在SMN1基因外显子7缺失,与RFLP的结果一致(诊断符合率为100%)。结论：等位基因特异性扩增是既简便又实用的SMA基因诊断方法。     

31例儿童脊髓性肌萎缩症临床与基因分析

目的探讨脊髓性肌萎缩症(SMA)的临床表型及基因型特点。方法回顾分析2014年2月至2019年5月确诊的31例脊髓性肌萎缩症患儿的临床资料。结果 31例SMA患儿中,男女比例1.8:1;6月龄内起病12例(38.7%),～18月龄起病17例(54.8%),18月龄后起病2例(6.5%)。首发症状为肌张力低下13例(41.9%),肌力下降9例(29.0%),步态异常5例(16.1%),生长迟缓4例(12.9%)。肌无力主要以近端受累为主,下肢重于上肢,腱反射减弱或消失。在感觉或认知方面均无变化。采用MLPA行基因检测,31例患儿中,SMN1基因外显子7和外显子8纯合缺失29例(93.5%),仅外显子7缺失2例(6.5%),均为2型患儿。不同类型SMA的临床表型与SMN1基因缺失类型之间差异无统计学意义(P0.05)。2型和3型SMA患儿的SMN2基因拷贝数高于1型,3型SMA患儿的SMN2基因拷贝数明显高于2型,不同SMA临床表型与SMN2拷贝数分布差异有统计学意义(P0.05)。30例(96.8%)患儿的父母亲明确诊断为SMN1基因杂合缺失;1例患儿父亲明确诊断为SMN1杂合缺失,母亲未检测到。结论 SMN1基因的检测和分析对SMA患儿具有诊断意义。SMA临床表型的严重程度与SMN2基因拷贝数增加呈反比。     

同时检测两种运动神经元存活基因第7外显子缺失的简便方法及其临床应用

目的：建立同时检测运动神经元存活基因SMNT和SMNC第7外显子缺失的简便方法，用于儿童期起病的脊髓性肌萎缩症（SMA）的临床诊断。方法：应用聚合酶链反应（PCR）－限制性酶切技术，用一对引物同时扩增55例正常成年人和5例SMA患儿及其父母的SMN基因2个成员的第7外显子中的高度保守区，扩增产物经限制性内切酶酶切及非变性聚丙烯酰胺凝胶电泳。结果：此法可检测2个SMN基因第7外显子的缺失情况，经检测，55例正常成人均无SMNT基因第7外显子缺失，SMNC基因第7外显子缺失仅3例，5例SMA患儿的SMNT基因第7外显子均有缺失，患儿父母无SMNT基因和SMNC基因第7外显子缺失，结论：此法对检测2个SMN基因第7外显子的缺失提供了简便，特异，且适合临床特别是基层医院应用，优于PCRSSCP分析的方法。     

Deletion analyses of SMN1 and NAIP genes in Malaysian spinal muscular atrophy patients

BACKGROUND: The survival motor neuron 1 (SMN1) gene has been recognized to be responsible for spinal muscular atrophy (SMA) because it is homozygously deleted in more than 90% of SMA patients, irrespective of their clinical severity, whereas the neuronal apoptosis inhibitory protein (NAIP) gene is now considered to be a modifying factor of the severity of SMA. In Malaysia, it remains to be elucidated whether deletion of the SMN1 gene is also a main cause of SMA or whether deletion of the NAIP gene is found in the SMA patients. METHODS: To clarify the pathogenesis of SMA in Malaysia, a deletion analysis of the SMN1 and NAIP genes was performed in 24 Malaysian SMA patients. Deletion analysis of exons 7 and 8 of the SMN1 gene was performed according to the method described by van der Steege et al., while deletion analysis of exon 5 of the NAIP gene was performed according to a method described by Roy et al. RESULTS: Homozygous deletion of SMN1 exon 7 and exon 8 were identified in 19 out of 24 patients (79%). As to the NAIP gene, deletion of exon 5 was detected in six out of 24 patients (25%). NAIP gene deletion was correlated with severity of the disease. CONCLUSIONS: Deletion of the SMN1 exon 7 is a major cause of SMA in Malaysia, and NAIP gene deletions are not rare in type I SMA in Malaysia. The lower percentage of the SMN1 gene deletion may be due to the possibility that the present study included some patients without SMN1 gene abnormality and/or some patients with non-deletion type mutations in the SMN1 gene.     

Molecular analysis of the SMN and NAIP genes in Iranian spinal muscular atrophy patients

Background:  Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder characterized by degeneration of spinal cord anterior horn cells, leading to muscular atrophy. SMA is clinically classified into three subgroups based on the age of onset and severity. The majority of patients with SMA have homozygous deletions of exons 7 and 8 of the survival motor neuron ( SMN ) gene. The purpose of the present study was to determine the frequency of SMN and neuronal apoptosis inhibitory protein ( NAIP ) gene deletions in Iranian SMA patients. Experience in prenatal diagnosis of SMA in this population is also reported.
Methods:  To study the frequency of deletions of SMN and NAIP genes in an Iranian sample group, 75 unrelated SMA patients (54 type I, eight type II and 13 type III) were analyzed according to the methods described by van der Steege et al and Roy et al .
Results:  Homozygous deletion of SMN1 exons 7 and/or 8 were identified in 68 out of 75 patients (90%). Deletion of exon 5 of the NAIP gene was found in 40/54 of type I, 2/8 of type II and 1/13 of type III patients.
Conclusions:  Deletion of the SMN1 gene is a major cause of SMA in Iran, and NAIP gene deletions were common in the present patients with type I SMA. Also, the incidence of NAIP deletion is higher in more severe SMA.     

Molecular diagnosis of spinal muscular atrophy

The frequency of deletions within the survival motor neurone (SMN) and neuronal apoptosis inhibitory protein (NAIP) genes in patients with spinal muscular atrophy (SMA), and the impact of this on the diagnosis and prenatal diagnosis of SMA, were investigated by molecular analysis of stored DNA and retrospective review of case notes. In type I SMA, 16 of 17 cases were homozygously deleted for exons 7 and 8 of SMN, 14 of 17 were homozygously deleted for exon 5 of NAIP, and 13 of 17 were deleted for both. In types II and III SMA, seven of nine cases were deleted for exons 7 and 8 of SMN. Deletions of SMN and NAIP occurred in four of nine cases. With one exception, the deletion genotypes of probands, affected siblings, and terminated fetuses were identical. Molecular studies are replacing conventional investigations for SMA and have a high uptake prenatally.

     

SMN2 and NAIP gene dosages in Vietnamese patients with spinal muscular atrophy

Background: The SMN1 gene is now recognized as a spinal muscular atrophy (SMA)-causing gene, while SMN2 and NAIP have been characterized as a modifying factor of the clinical severity of SMA. Gene dosage of SMN2 is associated with clinical severity of SMA. But the relationship between gene dosage of NAIP and clinical severity of SMA remains to be clarified, although complete deletion of NAIP is frequent in type I patients.
Methods: To evaluate the contribution of the SMN2 and NAIP gene dosages to SMA, quantitative real-time polymerase chain reaction was used to measure copy numbers of SMN2 and NAIP in 34 Vietnamese SMA patients lacking SMN1 (13 type I, 11 type II and 10 type III patients).
Results: The SMN2 copy number in type I patients was significantly lower than that in type II–III patients, which was compatible with the previous reports. In contrast, 25 out of 34 patients had only zero or one copy of NAIP , while 50 out of 52 controls had two or more copies. For NAIP (+) genotype, six out of 13 type I patients, eight out of 11 type II patients and six out of 10 type III patients carried one NAIP copy.
Conclusions: The SMN2 copy number was related to the clinical severity of SMA among Vietnamese patients. The presence of one NAIP copy, that is, heterozygous NAIP deletion, was common in Vietnamese SMA, regardless of clinical phenotype.     

儿童型脊肌萎缩症SMN基因缺失与微突变检测

目的：研究儿童型脊肌萎缩症(SMA)患者中运动神经元生存基因缺失与微突变情况。方法：收集经临床和肌肉活检确诊的SMA I~III型25例,其中I型5例,II型3例,III 17例及直系亲属24例。采用PCR-RFLP检测SMNt缺失情况,对无SMNt缺失的患者及SMA直系亲属,应用PCR-SSCP结合DNA序列分析的方法,进行SMN基因微突变分析。结果：5例I型和3例II型SMA患者均见SMNt缺失,缺失率100%,6例III型见缺失,缺失率35%(6/17)。11例无缺失的SMA III型患者的gDNA编码区域未发现微突变;24例SMA的直系亲属中未发现SMN基因缺失及突变。结论：①检测到SMNt外显子7缺失可作为SMA的确诊手段,有望替代肌电图和肌活检等有创检查;②对无SMNt外显子7缺失的III型SMA患者,要结合临床进行诊断;③该组无SMNt缺失的III型患者未发现微突变,提示存在遗传异质性。[中国当代儿科杂志,2005,7(6):489-492]