SPG4基因的遗传学研究

遗传性痉挛性截瘫(hereditary spastic paraplegia,HSP),又称为家族性Strümpell-Lorrain病,是一种具有临床及遗传高度异质性的神经系统遗传病,患病率为2/10万～9.6/10万,表现为缓慢进展的双下肢无力及痉挛性截瘫.根据遗传方式不同HSP可分为常染色体显性遗传、常染色体隐性遗传和X-连锁隐性遗传,以常染色体显性遗传最常见.目前已经发现40个HSP基因位点,已克隆19个疾病基因.其中spastin基因突变所致的遗传性痉挛性截瘫4型(spastic paraplegia-4,SPG4)约占常染色体显性遗传的HSP的40%.基因检测是诊断该病的金标准,有助于早期诊断、症状前诊断及产前诊断.动物模型的研究对揭示HSP的分子病理机制有重要作用,本文就SPG4基因的遗传学研究作一概述.     

遗传性痉挛性截瘫的遗传学研究进展

遗传性痉挛性截瘫是一种遗传学上很受关注的神经性遗传疾病 ,在遗传学和临床表现上都有很强的异质性。本文综述了遗传性痉挛性截瘫的分类和遗传特点 ;按遗传特点的不同对各种类型的痉挛性截瘫及其相关基因的研究进展进行了全面总结 ;并对其研究意义及前景作了展望     

遗传性痉挛性截瘫12例临床报告

目的研究遗传性痉挛性截瘫的临床表现和遗传特点。方法回顾性分析12例患者的临床资料。结果本组起病年龄为10～52岁,平均年龄22岁;35岁以下11例,35岁以上1例;单纯型9例,复杂型3例;3个家族有阳性家族史,共7例患者,散发病例5例。结论本组遗传性痉挛性截瘫患者多于青少年或青年发病,男性多于女性,单纯性较复杂型多见,遗传方式以常染色体显性遗传多见。     

遗传性痉挛性截瘫的遗传学研究进展

遗传性痉挛性截瘫是一种遗传学上很受关注的神经性遗传疾病,在遗传学和临床表现上都有很强的异质性。本综述了遗传性痉挛性截瘫的分类和遗传特点;按遗传特点的不同对各种类型的痉挛性截瘫及其相关基因的研究进展进行了全面总结,并对其研究意义及前景作了展望。     

AAA ATP酶与遗传性痉挛性截瘫

遗传性痉挛性截瘫是一种具有高度临床和遗传异质性的神经系统变性性疾病.现已定位35型,17型致病基因已被克隆.其中呈显性遗传的第4型和呈隐性遗传的第7型是较常见的亚型.它们的致病基因分别编码蛋白spastin与paraplegin,二者同属于AAA ATP酶家族.现对研究较多的这两型进行综述,并借此反映该病近年来的研究进展.     

AAA ATP酶与遗传性痉挛性截瘫

遗传性痉挛性截瘫是一种具有高度临床和遗传异质性的神经系统变性性疾病.现已定位35型,17型致病基因已被克隆.其中呈显性遗传的第4型和呈隐性遗传的第7型是较常见的亚型.它们的致病基因分别编码蛋白spastin与paraplegin,二者同属于AAA ATP酶家族.现对研究较多的这两型进行综述,并借此反映该病近年来的研究进展.     

AAA ATP酶与遗传性痉挛性截瘫

遗传性痉挛性截瘫是一种具有高度临床和遗传异质性的神经系统变性性疾病.现已定位35型,17型致病基因已被克隆.其中呈显性遗传的第4型和呈隐性遗传的第7型是较常见的亚型.它们的致病基因分别编码蛋白spastin与paraplegin,二者同属于AAA ATP酶家族.现对研究较多的这两型进行综述,并借此反映该病近年来的研究进展.     

AAA ATP酶与遗传性痉挛性截瘫

遗传性痉挛性截瘫是一种具有高度临床和遗传异质性的神经系统变性性疾病.现已定位35型,17型致病基因已被克隆.其中呈显性遗传的第4型和呈隐性遗传的第7型是较常见的亚型.它们的致病基因分别编码蛋白spastin与paraplegin,二者同属于AAA ATP酶家族.现对研究较多的这两型进行综述,并借此反映该病近年来的研究进展.     

AAA ATP酶与遗传性痉挛性截瘫

遗传性痉挛性截瘫是一种具有高度临床和遗传异质性的神经系统变性性疾病.现已定位35型,17型致病基因已被克隆.其中呈显性遗传的第4型和呈隐性遗传的第7型是较常见的亚型.它们的致病基因分别编码蛋白spastin与paraplegin,二者同属于AAA ATP酶家族.现对研究较多的这两型进行综述,并借此反映该病近年来的研究进展.     

AAA ATP酶与遗传性痉挛性截瘫

遗传性痉挛性截瘫是一种具有高度临床和遗传异质性的神经系统变性性疾病.现已定位35型,17型致病基因已被克隆.其中呈显性遗传的第4型和呈隐性遗传的第7型是较常见的亚型.它们的致病基因分别编码蛋白spastin与paraplegin,二者同属于AAA ATP酶家族.现对研究较多的这两型进行综述,并借此反映该病近年来的研究进展.     

Tunisian hereditary spastic paraplegias: clinical variability supported by genetic heterogeneity

Hereditary spastic paraplegias (HSP) constitute a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by slowly progressive spasticity of the lower extremities. We performed the first clinical, epidemiological and genetic study of HSP in Southern Tunisia. We investigated 88 patients belonging to 38 unrelated Tunisian HSP families. We could establish the minimal prevalence of HSP in the district of Sfax at 5.75/100,000. Thirty‐one percent of the families had a pure HSP, whereas 69% had a complicated form. The mode of inheritance was almost exclusively compatible with an autosomal recessive trait (97%, 37/38). Taking into account previously published results and new data generated in this work, genetic studies revealed significant or putative linkage to known HSP loci in 13 families (34.2%) to either SPG11 (7/38, 18.4%), SPG15 (4/38, 10.5%) or to SPG4 and SPG5 in one family each. The linkage results could be validated through the identification of two recurrent truncating mutations (R2034X and M245VfsX246) in the SPG11 gene, three different mutations (Q493X, F683LfsX685 and the novel S2004T/r.?) in the SPG15 gene, the recurrent R499C mutation in the SPG4 gene as well as the new R112X mutation in the SPG5 gene. SPG11 and SPG15 are the major responsible HSP genes in Tunisia.     

Expanding the clinical spectrum of SPG11 gene mutations in recessive hereditary spastic paraplegia with thin corpus callosum

Hereditary spastic paraplegia (HSP) represents a large group of neurological disorders characterized by progressive spasticity of the lower limbs. One subtype of HSP shows an autosomal recessive form of inheritance with thin corpus callosum (ARHSP-TCC), and displays genetic heterogeneity with four known loci. We identified a consanguineous Egyptian family with five affected individuals with ARHSP-TCC. We found linkage to the SPG11 locus and identified a novel homozygous p.Q498X stop codon mutation in exon 7 in the SPG11 gene encoding Spatacsin. Cognitive impairment and polyneuropathy, reported as frequent in SPG11, were not evident. This family supports the importance of SPG11 as a frequent cause for ARHSP-TCC, and expands the clinical SPG11 spectrum.     

Hereditary spastic paraparesis: The real-world experience from a Neurogenetics outpatient clinic

IntroductionHereditary spastic paraplegias (HSP) are inherited disorders with progressive spastic gait disturbance. Advances in genetic research have improved their diagnosis but there is great uncertainty regarding the appropriate investigation strategies for HSPs. Our aim is to characterize a cohort of HSP, describing the phenotypic spectrum, genotype-specific differences and current functional status.MethodsWe performed a cross-sectional study with HSP affected patients in a tertiary center. We analyzed clinical features, diagnostic workup and follow-up of the patients.ResultsA total of 61 patients were identified with HSP. The median age of disease onset was 23 (IQR 30) years and a family history was positive in 73.8%. Most of them presented a pure phenotype and 52.4% had a confirmed genetic diagnosis: seventeen SPG4, four SPG11, two SPG7, two SPG78, one SPG3A, one SPG5, one SPG6, one SPG15, one SPG 31, one ARSACS and one X-ALD. Most families were diagnosed by single gene testing and, in six patients, molecular diagnosis was achieved with NGS techniques. In complex forms, the most striking clinical signs include cerebellar features in SPG7 and SPG78 and epilepsy in SPG6. After 24 (IQR 21) years of symptoms' onset, 60.4% of the patients are still able to walk independently and most of them engage in rehabilitation programs.ConclusionIn our cohort, HSP is usually not a life-limiting disorder. Accurate molecular characterization is essential to optimize care for patients and their families. Well-phenotyped cohorts are important to direct further etiological and treatment investigations.     

Novel mutations in the Atlastin gene (SPG3A) in families with autosomal dominant hereditary spastic paraplegia and evidence for late onset forms of HSP linked to the SPG3A locus

Hereditary spastic paraplegias (HSP) comprise a genetically and clinically heterogeneous group of neurodegenerative disorders characterised by progressive spasticity and hyperreflexia of the lower limbs. Autosomal dominant hereditary spastic paraplegia linked to the SPG3A locus on chromosome 14q11-21 accounts for approximately 10% of autosomal dominant hereditary spastic paraplegia (ADHSP). It is caused by mutations in the SPG3A gene encoding the protein atlastin. To date, only five disease-causing mutations in the SPG3A gene have been described. We analysed 13 SPG4-negative families for mutations in the SPG3A gene and identified a mutation in 38% (5/13). Two of the mutations are novel, c.481G>C (p.A161P) and c.740A>C (p.H247P). One of the novel mutations was found both in a family with early onset of symptoms and in a late onset family. Furthermore, we report on numerous polymorphisms detected in the SPG3A gene.     

Mental deficiency in three families with SPG4 spastic paraplegia

Mutations and deletions in the SPG4 gene are responsible for up to 40% of autosomal dominant hereditary spastic paraplegia (HSP). Patients have pyramidal signs in the lower limbs and some present additional features including cognitive impairment such as executive dysfunction or subcortical dementia. We report 13 patients from three SPG4 families, who had spastic paraplegia associated with mental retardation (n=1), extensive social dependence (n=10), or isolated psychomotor delay (n=2). In family FSP-698, 10 affected individuals had both HSP and mental deficiency leading to social dependence in 9 and institutionalization in 5. The mean age at onset of spastic paraplegia was 11+/-20 years, ranging from 1 to 51 years. This phenotype segregated either with a novel p.Glu442Lys mutation or the two previously described p.Arg459Thr and p.Arg499Cys substitutions in the SPG4 gene. Since two of these mutations were previously reported in families with a pure form of the disease, another genetic factor linked to SPG4 could be responsible for this complex phenotype.     

Autosomal dominant hereditary spastic paraplegia: Novel mutations in the <Emphasis Type="Italic">REEP1</Emphasis> gene (SPG31)

Background  

Mutations in the SPG4 gene (spastin) and in the SPG3A gene (atlastin) account for the majority of 'pure' autosomal dominant form of hereditary spastic paraplegia (HSP). Recently, mutations in the REEP1 gene were identified to cause autosomal dominant HSP type SPG31. The purpose of this study was to determine the prevalence of REEP1 mutations in a cohort of 162 unrelated Caucasian index patients with 'pure' HSP and a positive family history (at least two persons per family presented symptoms).     

SPG35 contributes to the second common subtype of AR‐HSP in China: frequency analysis and functional characterization of FA2H gene mutations

Hereditary spastic paraplegias (HSPs) encompass a clinically and genetically heterogeneous group of neurodegenerative disorders. Recently, mutations in fatty acid 2‐hydroxylase gene (FA2H) have been identified responsible for HSPs type 35 (SPG35). This study aims to define the contribution of FA2H to Chinese autosomal recessive HSP (AR‐HSP) patients and provide insights into the enzymatic functions of the novel mutations. Direct sequencing of FA2H was conducted in 31 AR‐HSP families and 55 sporadic cases without SPG11, SPG15, SPG5 and SPG7 gene mutations. Enzymatic activity of the mutated proteins was further examined. Three novel mutations were found in two Chinese families, including two compound heterozygous mutations (c.388C>T/p.L130F and c.506+6C>G) and one homozygous mutation (c.230T>G/p.L77R). The c.506+6C>G splice‐site mutation led to the deletion of exon 3. Measurement of enzymatic functions revealed a significant reduction in the enzymatic activity of FA2H associated with p.L130F and p.L77R. Overall, our data widens the spectrum of the mutations on FA2H, and functional analyses indicate that these mutations severely impair the enzymatic activity of FA2H. Furthermore, frequency analysis shows that SPG35 is the second most common subtype of AR‐HSP in China.     

Copy number variations in SPAST and ATL1 are rare among Brazilians

Copy number variations (CNV) may represent a significant proportion of SPG4 and SPG3A diagnosis, the most frequent autosomal dominant subtypes of hereditary spastic paraplegias (HSP). We aimed to assess the frequency of CNVs in SPAST and ATL1 and to update the molecular epidemiology of HSP families in southern Brazil. A cohort study that included 95 Brazilian index cases with clinical suspicion of HSP was conducted between April 2011 and September 2022. Multiplex Ligation Dependent Probe Amplification (MLPA) was performed in 41 cases without defined diagnosis by different massive parallel sequencing techniques (MPS). Diagnosis was obtained in 57/95 (60%) index cases, 15/57 (26.3%) being SPG4. Most frequent autosomal recessive HSP subtypes were SPG7 followed by SPG11, SPG76 and cerebrotendinous xanthomatosis. No CNVs in SPAST and ATL1 were found. Copy number variations are rare among SPG4 and SPG3A families in Brazil. Considering the possibility of CNVs detection by specific algorithms with MPS data, we consider that this is likely the most cost-effective approach to investigate CNVs in these genes in low-risk populations, with MLPA being reserved as an orthogonal confirmatory test.     

Amplicon-based high-throughput pooled sequencing identifies mutations in CYP7B1 and SPG7 in sporadic spastic paraplegia patients

Hereditary spastic paraplegia (HSP) is a neurodegenerative disorder defined clinically by progressive lower limb spasticity and weakness. HSP is a genetically highly heterogeneous condition with at least 46 gene loci identified so far, involving X-linked, autosomal recessive (AR) and autosomal dominant inheritance. For correct diagnosis, molecular testing is essential because clinical parameters by themselves are not reliable to differentiate HSP forms. The purpose of this study was to establish amplicon-based high-throughput genotyping for AR-HSP. A sample of 187 index cases with apparently sporadic or recessive spastic paraplegia were analyzed by applying an array-based amplification strategy. Amplicon libraries of the CYP7B1-(SPG5) and SPG7-gene were generated followed by a pooled next-generation sequencing (NGS) approach. We identified three SPG5 and seven SPG7 patients. All had one homozygous or two heterozygous mutations. In total, 20 distinct mutations (CYP7B1,n = 4and SPG7,n = 16) including two novel CYP7B1 mutations (p.G51R and p.E211KfsX3) and eight novel SPG7 mutations (p.Leu8delinsLeuLeu, p.W29X, p.R139X, p.R247X, p.G344D, p.Leu346_Leu347ins11, p.R398X and p.R398Q) were detected by this comprehensive genetic testing. Our study illustrates how amplicon-based NGS can be used as an efficient tool to study genotypes and mutations in large patient cohorts and complex phenotypes.     

Mutations in the motor and stalk domains of KIF5A in spastic paraplegia type 10 and in axonal Charcot-Marie-Tooth type 2

Spastic paraplegia type 10 (SPG10) is an autosomal dominant form of hereditary spastic paraplegia (HSP) due to mutations in KIF5A, a gene encoding the neuronal kinesin heavy chain implicated in anterograde axonal transport. KIF5A mutations were found in both pure and complicated forms of the disease; a single KIF5A mutation was also detected in a CMT2 patient belonging to an SPG10 mutant family. To confirm the involvement of the KIF5A gene in both CMT2 and SPG10 phenotypes and to define the frequency of KIF5A mutations in an Italian HSP patient population, we performed a genetic screening of this gene in a series of 139 HSP and 36 CMT2 affected subjects. We identified five missense changes, four in five HSP patients and one in a CMT2 subject. All mutations, including the one segregating in the CMT2 patient, are localized in the kinesin motor domain except for one, falling within the stalk domain and predicted to generate protein structure destabilization. The results obtained indicate a KIF5A mutation frequency of 8.8% in the Italian HSP population and identify a region of the kinesin protein, the stalk domain, as a novel target for mutation. In addition, the mutation found in the CMT2 patient strengthens the hypothesis that CMT2 and SPG10 are the extreme phenotypes resulting from mutations in the same gene.