遗传性痉挛性截瘫一家系(SPG4)的临床与遗传学特点

目的 探讨遗传性痉挛性截瘫(HSP)4型患者的临床特点和基因突变. 方法观察HSP4型患者1个家系4例患者的临床特点,抽取家系5个成员的外周血,选择与已知HSP致病基因位点在物理距离上紧密连锁的微卫星分子STR进行标记.连锁分析并构建其单体型后进行突变筛选.结果 基因分型结果显示了D2S2351与D2S2255与致病基因不排除连锁.其他位点LOD值为负值排除连锁,因此初步定位于HSP致病基因(SPG)4,所对应的候选基因是spastin基因.突变筛查发现患者spastin基因第8外显子1168位置碱基A/G杂合突变.结论该HSP家系患者具有典型临床表现,为spastin基因第8外显子1168核苷酸的位置上A/G杂合突变所致.     

贵州少数民族遗传性痉挛性截瘫患者spastin基因突变的研究

目的 研究贵州地区少数民族遗传性痉挛性截瘫(HSP)患者spastin基因突变的特征.方法 应用PCR产物直接DNA测序法,对贵州16例少数民族(布依、苗、彝族)HSP患者(其中14例患者来自3个常染色体显性遗传家系,2例散发患者)spastin基因的8、10、14号外显子进行分析.将测序结果与人类基因组SPG4基因序列进行比对.结果 16例患者的spastin基因8、10、14号外显子直接DNA测序结果均未发现有突变.结论 贵州少数民族HSP患者spastin基因8、10、14号外显子的突变可能较少见,其与汉族HSP患者的spastin基因突变形式可能不同.     

遗传性痉挛性截瘫一家系的临床特点与spastin基因突变分析

目的　探讨常染色体显性遗传的遗传性痉挛性截瘫 (SPG)一家系的临床特点,并行spastin基因突变分析。方法　对整个家系进行详细的临床检查,先证者和另一例家系内患者进行了心肌酶学、头颅核磁共振成像(MRI)、胸髓MRI、肌电图、体感诱发电位检查。应用聚合酶链式反应 单链构象多态性(PCR SSCP)结合DNA序列分析方法,检测该家系中所有 5例患者和 4名有血缘关系的健康人及家系外 50名无血缘关系健康对照者spastin基因的突变情况。结果　先证者和家系内另一例SPG患者胸髓MRI显示胸髓萎缩;PCR SSCP检测发现家系内患者均出现异常SSCP电泳带,经测序证实为Leu378Gln突变。结论　该常染色体显性遗传SPG家系的患者具有典型的临床表现,为spastin基因Leu378Gln突变所致。     

遗传性痉挛性截瘫SPG4和SPG3A基因突变和多态分析

目的 筛查并分析遗传性痉挛性截瘫(HSP)SPG4和SPG3A基因突变,了解中国人群这2个基因的突变特点.方法 联合应用变性高效液相色谱分析(DHPLC)和DNA序列分析方法对24例常染色体显性遗传的HSP(AD-HSP)家系的先证者和32例散发性HSP患者进行SPG4和SPG3A基因突变筛查,对24例AD-HSP家系的先证者进一步直接测序筛查这2个基因的突变.结果 在1个AD-HSP家系中发现1个位于SPG4基因上的新犁突变1616+1g→t杂合突变.在此家系中,共发现了3例现症患者和2例症状前患者.本组病例未检出SPG3A基因突变.此外,共发现了8种新的SPG4多态和3种新的SPG3A多态.结论 本组检测结果 丰富了SPG4和SPG3A基因的突变和多态库.这2个基因突变在本组病例中较少见,需要继续分析其他基因.     

遗传性痉挛性截瘫spastin、atlastin和paraplegin基因突变分析

目的探讨遗传性痉挛性截瘫(HSP)spastin、atlastin和parap legin基因的突变特点。方法应用聚合酶链反应-单链构象多态性(PCR-SSCP)结合DNA序列分析方法对24个常染色体显性遗传HSP家系和14例散发患者进行spastin基因和atlastin基因突变分析;对12个常染色体隐性遗传HSP家系和14例散发患者进行parap legin基因突变分析。结果在5个不同的常染色体显性遗传HSP家系中发现4个spastin基因新突变(1223 insCTCA、1258T→A,1293A→G和1668delCTA),在2例散发患者中发现2个spastin基因多态(IVS1-31C→G和IVS2-47A→G);在常染色体显性遗传HSP家系和散发患者中未发现atlastin基因突变或多态;在常染色体隐性遗传HSP家系和散发患者中未发现致病突变,仅在2例散发患者中发现2个parap legin基因多态(2063G→A及2066G→A)。结论我国遗传性痉挛性截瘫患者中spastin基因突变较常见,atlastin和parap legin基因的突变率可能较低。     

贵州部分少数民族遗传性痉挛性截瘫Spastin基因突变研究

目的筛查及分析遗传性痉挛性截瘫(HSP)Spastin基因突变,了解贵州地区少数民族(彝族、布衣族、苗族)Spastin基因突变特点。方法应用PCR产物直接DNA测序法,对9例HSP患者(包括3个家系中7例现证者和2例散发患者)Spastin基因1-17号外显子进行突变筛查;被发现存在突变的外显子,其次行家系内其他成员相对应外显子的筛查。结果在9例HSP患者中发现家系3两例患者(Ⅴ24、Ⅴ25)的Spastin基因第4号外显子同一位点上发生错义突变c.847C>T,其他参与抽血的亲属均无该位点突变,推测该位点的突变为一多态。另外的突变位点均位于外显子序列前后的内含子区域。结论此次贵州地区部分少数民族spastin基因突变率低,与国内文献报道的汉族人群不同。     

遗传性痉挛性截瘫paraplegin基因的突变分析

目的探讨paraplegin基因在中国人遗传性痉挛性截瘫(HSP或SPG)中的突变特点,为该病的基因诊断奠定基础。方法应用聚合酶链反应单链构象多态性(PCRSSCP)结合DNA序列分析方法,对来自全国8个常染色体隐性遗传HSP家系的先证者和14例散发性HSP患者进行paraplegin基因突变分析。结果所有外显子均可扩出,发现15号外显子上2例先证者出现异常SSCP条带,经DNA序列分析发现2063及2066位点上存在碱基G被A替换,但家系内不存在共分离的现象,且正常对照者也存在G被A替换,考虑为多态,其中G2066A为首次发现。结论Paraplegin基因突变可能在中国人HSP患者中少见。2063G→A及2066G→A是paraplegin基因的两个多态性改变,其中2066G→A为首次发现。     

遗传性痉挛性截瘫atlastin基因突变分析

目的 探讨中国人遗传性痉挛性截瘫（HSP）atlastin基因的突变特点,为HSP的基因诊断奠定基础。方法 应用聚合酶链反应一单链构象多态性（PCR-SSCP）结合DNA序列分析方法,对来自全国20例常染色体显性遗传HSP家系的先证者和10例散发性HSP患者进行了atlastin基因突变分析。结果 在20例常染色体显性遗传HSP家系的先证者和10例散发性HSP患者中均未发现异常SSCP条带,第7号外显子直接DNA序列分析亦无异常。结论 atlastin基因突变可能在中国人HSP患者中少见。     

广西地区一家系先天性肌强直的临床资料和基因测定

目的探讨先天性肌强直(MC)一家系的临床特点及CLCN1基因部分外显子位点突变的情况。方法收集广西壮族自治区1例MC患者的临床及家系资料,提取家系成员和对照组(无血缘关系的健康体检者6名)的外周静脉血DNA,采用聚合酶链反应(PCR)扩增部分CLCN1基因,测定该基因第3、5、8、13、14、15、16号外显子序列,并对突变位点进行分析。结果 MC患者的6名家系和对照组成员的PCR扩增凝胶电泳分析表明,同一引物对应各样本条带均无显著差异;CLCN1基因被测序的第3、5、8、13、14、15、16号外显子序列均未发现有突变位点。结论该MC患者及家系中患者的MC致病基因位点未位于CLCN1基因这7个外显子序列上,需要对CLCN1基因全外显子序列进行检测分析。     

腓骨肌萎缩症CMTX1型的间隙连接蛋白32基因突变检测

目的检测无基因重复的腓骨肌萎缩症患者间隙连接蛋白32(connexin32,Cx32)基因的突变情况。方法应用变性高效液相色谱(DHPLC)结合混合样品池法和脱氧核糖核酸(DNA)序列测定对1个临床可疑的X连锁显性遗传的腓骨肌萎缩症CMTX1型家系的先证者和15名家庭成员及60名家系外健康对照者进行Cx32基因外显子2的基因编码区突变检测,分3个片段扩增其基因编码区全长。结果先证者在片段2的DHPLC中发现杂合双峰,经DNA序列测定证实其Cx32外显子2发生Leu89Pro(266T→C)错义突变;家系内其他4例发病者和5名未发病者Cx32外显子2都有与先证者一致的DHPLC杂合双峰。60名健康对照者中未发现上述改变。结论Leu89Pro是该家系的致病性突变。该突变体的致病机制如何,有待于做进一步研究。     

Missense and splice site mutations in SPG4 suggest loss-of-function in dominant spastic paraplegia

We studied nine Italian families with a pure form of autosomal dominant spastic paraplegia (ADHSP) to assess the frequency of mutations in the SPG4 gene. We observed marked intrafamilial variability in both age-at-onset and clinical severity, ranging from severe congenital presentation to mild involvement after age 55 years to healthy carriers of the mutation after age 70. Four of nine probands harboured SPG4 mutations, We identified three new SPG4 mutations, all predicting a loss-of-function with apparently important consequences for spastin function. RT-PCR studies predict loss-of-function as a possible mechanism leading to spastin-related HSP. The current study expands the spectrum of allelic variants in SPG4, confirming their pathological significance in pure AD-HSP and suggesting implications for the presumed function of spastin. Received: 15 December 2000, Received in revised form: 29 May 2001, Accepted: 18 June 2001     

SPG4 founder effect in French Canadians with hereditary spastic paraplegia

BACKGROUND: The most common cause of autosomal dominant Hereditary Spastic Paraplegia (HSP) is mutations in the SPG4 gene. We have previously identified novel SPG4 mutations in a collection of North American families including the c.G1801A mutation present in two families from Quebec. The aim of this study is to estimate the frequency of the c.G1801A mutation in the French Canadian (FC) population and to determine whether this mutation originates from a common ancestor. METHODS: We collected and sequenced exon 15 in probands of 37 families. Genotypes of markers flanking the SPG4 gene were used to construct haplotypes in five families. Clinical information was reviewed by a neurologist with expertise in HSP. RESULTS: We have identified three additional unrelated families with the c.G1801A mutation and haplotype analysis revealed that all five families share a common ancestor. The mutation is present in 7% of all our FC families and explains half of our spastin linked FC families. The phenotype associated with the c.G1801A genotype is pure HSP with bladder involvement. CONCLUSION: In this study we have determined that the relative frequency of the c.G1801A mutation in our FC collection is 7%, and approximately 50% in the spastin positive FC group. This mutation is the most common HSP mutation identified in this population to date and is suggestive of a founder effect in Quebec.     

Spastin related hereditary spastic paraplegia with dysplastic corpus callosum

Thin corpus callosum has been recently observed in two patients with an autosomal dominant trait of hereditary spastic paraplegia (HSP) linked to a novel mutation in the spastin gene (SPG4). In the same two patients cerebellar atrophy has been found. Reportedly, in other members of the same family, there has been a variable presence of mental retardation. We report on the clinical and genetic investigation of an Austrian family with a novel mutation in the spastin gene. Genetic analysis of the SPG4 locus revealed a mutation (C1120A) and a known intronic polymorphism (996-47G>A) of the spastin gene. In one affected family member, previously undescribed dysplasia of the corpus callosum (CC) was found in conjunction with otherwise uncomplicated HSP. Dysplastic CC was not paralleled with cortical atrophy, cognitive impairment or other phenotypic variations. Two further affected family members showed the same mutation and polymorphism, but no evidence of CC abnormalities. We conclude that apparently pure HSP may present with MRI features of dysplastic CC. This finding extended the spastin-related phenotype which is distinct from previous reports of thin CC in HSP.     

Hereditary spastic paraplegia: clinical genetic study of 15 families

BACKGROUND: Autosomal dominant hereditary spastic paraplegia (ADHSP) is mainly caused by mutations in the SPG4 gene, which encodes a new member of the AAA (adenosine triphosphatases associated with diverse cellular activities) protein family (spastin). Accumulation of genotype-phenotype correlation is important for better understanding of SPG4-linked hereditary spastic paraplegia. OBJECTIVES: To perform a clinical and genetic study of families with ADHSP and to perform the functional analysis of the founder mutation discovered in the SPG4 gene. DESIGN: Genetic and clinical study.Patients Fifteen unrelated families with ADHSP originating from southern Scotland. MAIN OUTCOME MEASURES: Clinical assessment, linkage analysis, haplotype study, expression of mutant spastin protein in cultured cells. RESULTS: Nine families with ADHSP were linked to the SPG4 locus at 2p21-p24. Sequence analysis of SPG4showed a novel N386S mutation in all 9 of these families. Expression of mutant spastin showed aberrant distribution in cultured cells. Haplotype analysis suggested the existence of a common founder. Clinical examination of the affected members carrying the mutation showed phenotypic variations including broad range of age at onset and disease duration and additional neurologic features such as mental retardation. Magnetic resonance imaging demonstrated unique features, including thin corpus callosum and atrophy of the cerebellum in 2 patients. Linkage and sequence analyses showed no evidence of linkage to the currently known ADHSP loci in the remaining 6 families. CONCLUSIONS: A founder SPG4 mutation N386S was identified in the families with ADHSP originating from southern Scotland. Clinical investigation showed intrafamilial and interfamilial phenotypic variations. The genetic study demonstrated evidence of further genetic heterogeneity in ADHSP.     

Investigation of mitochondrial function in hereditary spastic paraparesis

Following the association of hereditary spastic paraparesis (HSP) with mutation in the paraplegin gene (SPG7) and mitochondrial dysfunction, we wished to investigate whether mitochondrial dysfunction might be associated with other forms of HSP. Five cases of HSP caused by mutation in the spastin gene (SPG4) and nine cases with HSP with mutation in the spastin and paraplegin genes excluded (non-SPG4/SPG7), were investigated for mitochondrial dysfunction. Muscle tissue from the HSP groups and a control group was analysed histochemically and spectrophotometrically for mitochondrial dysfunction. A significant decrease in mitochondrial respiratory chain complexes I and IV was demonstrated in the non-SPG4/SPG7 group. No abnormality was detected in the SPG4 group. We therefore conclude that there is evidence for mitochondrial dysfunction in non-SPG4/SPG7 HSP. There is no evidence for mitochondrial dysfunction in the pathogenesis of spastin-related HSP.     

Hereditary spastic paraplegia with cerebellar ataxia: a complex phenotype associated with a new SPG4 gene mutation

Complex forms of hereditary spastic paraplegia (HSP) are rare and usually transmitted in an autosomal recessive pattern. A family of four generations with autosomal dominant hereditary spastic paraplegia (AD-HSP) and a complex phenotype with variably expressed co-existing ataxia, dysarthria, unipolar depression, epilepsy, migraine, and cognitive impairment was investigated. Genetic linkage analysis and sequencing of the SPG4 gene was performed and electrophysiologic investigations were carried out in six individuals and positron emission tomography (PET) in one patient. The disease was linked to the SPG4 locus on chromosome 2p as previously reported for pure HSP. Sequence analysis of the SPG4 (spastin) gene identified a novel 1593 C > T (GLN490Stop) mutation leading to premature termination of exon 12 with ensuing truncation of the encoded protein. However, the mutation was only identified in those individuals who were clinically affected by a complex phenotype consisting of HSP and cerebellar ataxia. Other features noted in this kindred including epilepsy, cognitive impairment, depression, and migraine did not segregate with the HSP phenotype or mutation, and therefore the significance of these features to SPG4 is unclear. Electrophysiologic investigation showed increased central conduction time at somatosensory evoked potentials measured from the lower limbs as the only abnormal finding in two affected individuals with the SPG4 mutation. Moreover, PET of one patient showed significantly relatively decreased regional cerebral blood flow in most of the cerebellum. We conclude that this kindred demonstrates a considerable overlap between cerebellar ataxia and spastic paraplegia, emphasizing the marked clinical heterogeneity of HSP associated with spastin mutations.     

Three novel mutations of the spastin gene in Chinese patients with hereditary spastic paraplegia

BACKGROUND: Hereditary spastic paraplegia is a group of genetically heterogeneous neurodegenerative disorders characterized by progressive spasticity of the lower limbs. The most common form of hereditary spastic paraplegia is caused by mutations in the spastin gene (SPG4), which encodes spastin, an adenosine triphosphatase associated with various cellular activities protein. OBJECTIVE: To investigate the Chinese patients with hereditary spastic paraplegia for mutations in SPG4. METHODS: DNA samples from 31 unrelated patients were analyzed for mutations in SPG4 by single-strand conformation polymorphism analysis and direct sequencing. All DNA samples were screened for mutations by the polymerase chain reaction, followed by electrophoresis and silver staining. Each new variant identified was analyzed in 50 control subjects to determine whether it is a polymorphism or a mutation. RESULTS: Three novel mutations were detected in 4 affected individuals, including 2 missense mutations (T1258A and A1293G) and 1 deletion mutation (1668-1670delCTA). CONCLUSIONS: To our knowledge, this is the first report of SPG4 mutations in the People's Republic of China. The percentage of involved Chinese families with autosomal dominant hereditary spastic paraplegia with an SPG4 mutation is 18% (4/22), lower than the estimated 40% linked to this locus.     

Motor system abnormalities in hereditary spastic paraparesis type 4 (SPG4) depend on the type of mutation in the spastin gene

BACKGROUND: Hereditary spastic paraparesis (HSP) denotes a group of inherited neurological disorders with progressive lower limb spasticity as their clinical hallmark; a large proportion of autosomal dominant HSP belongs to HSP type 4, which has been linked to the SPG4 locus on chromosome 2. A variety of mutations have been identified within the SPG4 gene product, spastin. OBJECTIVE: Correlation of genotype and electrophysiological phenotype. MATERIAL: Two large families with HSP linked to the SPG4 locus with a very similar disease with respect to age of onset, progression, and severity of symptoms. METHODS: Mutation analysis was performed by PCR from genomic DNA and cDNA, and direct sequencing. The motor system was evaluated using transcranial magnetic stimulation. RESULTS: Patients differ in several categories depending on the type of mutation present. CONCLUSIONS: For the first time in hereditary spastic paraparesis, a phenotypic correlate of a given genetic change in the spastin gene has been shown.