不完全外显的遗传性痉挛性截瘫一家系临床与致病基因排除定位分析

目的 描述一个遗传了4代的不完全外显的遗传性痉挛性截瘫(hereditary spastic paraplegia,SPG)大家系的临床特征,并进行致病基因排除定位分析.方法 对SPG家系内11例患者的临床资料进行回顾性分析,并采用荧光多重PCR、毛细管凝胶电泳、Linkage软件包,选择对已定位常染色体显性遗传致病基因位点附近微卫星标记进行连锁分析.结果 该SPG家系的11例患者的发病年龄2～10岁,表现为缓慢进展的双下肢僵硬无力,四肢肌张力轻度增高,双上肢为主的腱反射亢进,剪刀步态和病理征阳性,无小便失禁或尿频、感觉障碍、眼震、痴呆等;遗传学分析该家系符合常染色体显性遗传,但外显不完全,连锁分析和突变分析发现该家系与已知的常染色体显性遗传SPG致病基因位点不连锁.结论 该SPG家系具有典型的"单纯型"痉挛性截瘫临床特点,发病年龄早,上肢体征较下肢明显,遗传学分析不支持该家系与已定位常染色体显性遗传位点相连锁,是一种新的SPG亚型.     

中国人遗传性痉挛性截瘫spastin基因突变研究

目的 探讨中国人遗传性痉挛性截瘫（hereditary spastic paraplegia,HSP)spastin基因的突变特点，为该病的基因诊断提供依据。方法 应用聚合酶链反应—单链构象多态性(PCR—single strand conformation polymorphism，PCR—SSCP)结合DNA序列分析方法，对22个常染色体显性遗传HSP家系的先证者和9例散发性HSP患者的spastin基因进行研究，对发现异常SSCP条带的家系内成员进行突变研究。结果 在22例常染色体显性遗传HSP家系的先证者和9例散发性HSP患者中发现异常SSCP条带6例，进行DNA序列分析，共发现3种spastin基因突变，为外显子8的T1258A和A1293G，外显子14的1667delACT或1668delCTA或1669delTAC，均未见报道，突变位点均位于spastin基因功能区域，其中两个家系存在同一种突变(T1258A)，各突变家系内患者存在同样的异常SSCP条带。结论 中国人遗传性痉挛性截瘫患者存在spastin基因突变，该基因在中国人常染色体显性遗传的遗传性痉挛性截瘫家系中的突变率较低(18．2％)，点突变是主要的突变形式，外显子8可能是中国人spastin基因的突变热点。     

常染色体显性遗传性痉挛性截瘫的分子遗传学进展

遗传性痉挛性截瘫(SPG)是一组以双下肢进行性肌张力增高和无力、剪刀步态为特征的具有明显临床和遗传异质性的神经系统变性疾病,多数呈常染色体显性遗传,也可呈常染色体隐性或X连锁遗传。根据临床表现不同,即是否伴有脊髓外损害将SPG分为复杂型和单纯型。复杂型和单纯型都可呈常染色体显性遗传,到目前为止已定位15型,其中有9型的疾病基因已被克隆。本文主要对各型常染色体显性遗传SPG的分子遗传学进展加以综述。     

伴远端肌萎缩遗传性痉挛性截瘫的分子遗传学研究进展

遗传性痉挛性截瘫(hereditary spastic paraplegia,HSP or SPG)是一组具有高度临床和遗传异质性的神经系统变性疾病,以缓慢进展的双下肢痉挛性截瘫和无力为主要临床特点,病理特点为皮质脊髓束及后索的轴突纤维退行性变.根据是否伴有脊髓外损害,又可将HSP分为复杂型和单纯型.近年来发现越来越多的HSP伴有远端肌萎缩症状,其致病基因到目前为止已定位16型,其中13型已被克隆.随着越来越多的基因被克隆,本病的分子遗传学机制将逐渐被揭示.     

遗传性痉挛性截瘫常见亚型的表型特征及致病基因

遗传性痉挛性截瘫(hereditary spastic paraplegia, HSP)是一组具有高度临床和遗传异质性的神经退行性疾病, 其特征是进行性加重的双下肢痉挛和无力。HSP的发病机制和临床特征因致病基因不同而有很大的差异, 临床上诊断与鉴别诊断较为困难。本文就HSP常见致病基因及表型特征进行综述, 以提高临床医生对HSP的早期诊断效率。     

SPG3A-遗传性痉挛性截瘫中的不完全外显性和遗传早现

目的通过分析遗传性痉挛性截瘫一家系(hereditary spastin paraplegia,HSP)SPG3A/atlastin基因突变与临床特征的关系,阐明显性遗传中的不完全外显性和遗传早现。方法收集1个HSP家系的临床资料,对家系成员以及100名正常对照进行神经系统检查,并对atlastin全编码序列和基因SPG4/spastin(S44和P45Q)和SPG6/nipa1含([GCG]5-11)的第1外显子进行DNA测序并分析。结果在先证者及其受累儿子和无症状父亲的外周血DNA中发现SPG3AV253I突变而在家系其他成员和正常对照个体中均未发现该突变。结论这是第2例由于SPG3AV253I突变引起的不完全外显性的家系报道,家系中有着相同突变位点个体的标记表型变异(遗传不外显)显示了遗传修饰和环境因素的影响。家系中越来越早的发病和症状加重与遗传早现相一致,这在SPG3A-HSP中尚属首例。     

一个遗传性痉挛性截瘫家系的全外显子测序分析及产前诊断

目的对一个常染色体显性遗传性痉挛性截瘫(hereditaryspasticparaplegia,HSP)家系进行全基因组外显子测序分析,找出致病的基因突变位点。方法收集一个遗传性痉挛性截瘫家系,提取先证者、先证者父母的DNA进行全外显子组捕获和测序,锁定候选基因致病位点,针对变异位点在该家系6名患者和9名正常人中进行Sanger测序验证,然后通过羊水穿刺和Sanger测序进一步对1例胎儿羊水进行产前诊断。结果该家系中6例病人均在ATL1基因的同一位点处发生突变(c.715CT,p. R239C),家系中9例正常人和1例胎儿羊水中均未发现该突变。结论应用全外显子测序技术对遗传性痉挛性截瘫家系进行诊断,明确致病位点,有助于该家系的遗传咨询和产前诊断。     

遗传性痉挛性截瘫4型的研究进展

痉挛性截瘫4型(SPG4)是常染色体遗传性痉挛截瘫疾病中最常见的类型, 主要临床特征为典型的单纯型遗传性痉挛性截瘫, 神经功能损害仅限于下肢痉挛无力、高渗性膀胱障碍和下肢振动觉轻度减弱, 不伴随出现神经萎缩、共济失调、认知障碍、癫痫发作和肌张力障碍等特征。SPAST是引起SPG4的主要致病基因, 现已发现多种不同的SPAST致病变异体。该疾病存在高度临床异质性, 相同致病变异体在不同患者间甚至在同一家系间也可表现出发病年龄与严重程度的差异。关于SPG4基因型和表型的相关性缺乏系统的研究, 致病机制目前尚存在争议。本文对该疾病的临床特征、致病基因特点、基因型与表型的相关性、致病机理等进行了综述, 以期为该疾病的临床诊疗提供参考。     

心脏病的遗传

本文论述了孟德尔式、染色体及多基因三种主要遗传学原则,列举有心脏病表现的遗传性综合征及介绍遗传咨询过程,以期帮助心脏病学家能在医学实践中运用遗传学的概念。孟德尔式遗传孟德尔式遗传包括常染色体显性遗传、常染色体隐性遗传及X连锁隐性遗传三个类型。常染色体显性遗传如果一个病人只需一个致病基因就可致     

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。     

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.     

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.     

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.     

Clinical and genetic analysis of a Korean family with hereditary spastic paraplegia type 3

Hereditary spastic paraplegia (HSP) is a neurodegenerative disease characterized by progressive spasticity in the lower extremities. Mutations in the atlastin GTPase 1 (ATL1) gene cause approximately 10% of autosomal dominantly inherited HSP. For many subjects with an ATL1 mutation, spastic gait begins in early childhood and does not significantly worsen, even over many years; such cases resemble spastic diplegic cerebral palsy. Herein we report a heterozygous R239C mutation in the ATL1 gene in a Korean family. The family members exhibited early onset pure spastic paraplegia and had been previously diagnosed with the diplegic form of cerebral palsy. We suggest that spastic paraplegia type 3 (SPG3A) be included in the differential diagnosis of early onset spastic paraplegia. To the best of our knowledge, this is the first report of a genetically confirmed family affected with SPG3A in Korea.     

遗传性痉挛性截瘫11型研究进展

遗传性痉挛性截瘫是一种遗传性、神经退行性变的疾病,具有明显的遗传异质性,遗传形式多样.遗传性痉挛性截瘫11型是隐形遗传尤其是合并有胼胝体发育不良患者中最常见的类型,现就近几年来该病的研究进展,从遗传性痉挛性截瘫11型的基因定位和克隆,基因突变情况及其临床表现,诊断与鉴别诊断、发病机制等方面进行全面的介绍.     

Mutation analysis of the spastin gene (SPG4) in patients in Germany with autosomal dominant hereditary spastic paraplegia

Hereditary spastic paraplegias (HSP) comprise a genetically and clinically heterogeneous group of neurodegenerative disorders characterized by progressive spasticity and hyperreflexia of the lower limbs. Autosomal dominant hereditary spastic paraplegia 4 linked to chromosome 2p (SPG4) is the most common form of autosomal dominant hereditary spastic paraplegia. It is caused by mutations in the SPG4 gene encoding spastin, a member of the AAA protein family of ATPases. In this study the spastin gene of HSP patients from 161 apparently unrelated families in Germany was analyzed. The authors identified mutations in 27 out of the 161 HSP families; 23 of these mutations have not been described before and only one mutation was found in two families. Among the detected mutations are 14 frameshift, four nonsense, and four missense mutations, one large deletion spanning several exons, as well as four mutations that affect splicing. Most of the novel mutations are located in the conserved AAA cassette-encoding region of the spastin gene. The relative frequency of spastin gene mutations in an unselected group of German HSP patients is approximately 17%. Frameshift mutations account for the majority of SPG4 mutations in this population. The proportion of splice mutations is considerably lower than reported elsewhere.     

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.     

Expanding SPG7 dominant optic atrophy phenotype: Infantile nystagmus and optic atrophy without spastic paraplegia

Spastic paraplegia is a neurodegenerative disorder characterized by progressive leg weakness and spasticity due to degeneration of corticospinal axons. SPG7 encodes paraplegin, and pathogenic variants in the gene cause hereditary spastic paraplegia as an autosomal recessive trait. Various ophthalmological findings including optic atrophy, ophthalmoplegia, or nystagmus have been reported in patients with spastic paraplegia type 7. We report a 15-year-old male patient with a novel heterozygous variant, c.1224T>G:p.(Asp408Glu) in SPG7 (NM_003119.3) causing early onset isolated optic atrophy and infantile nystagmus prior to the onset of neurological symptoms. Therefore, SPG7 should be considered a cause of infantile nystagmus with optic atrophy.     

Mutations in phospholipase DDHD2 cause autosomal recessive hereditary spastic paraplegia (SPG54)

Hereditary spastic paraplegias (HSP) are a genetically heterogeneous group of disorders characterized by a distal axonopathy of the corticospinal tract motor neurons leading to progressive lower limb spasticity and weakness. Intracellular membrane trafficking, mitochondrial dysfunction and myelin formation are key functions involved in HSP pathogenesis. Only recently defects in metabolism of complex lipids have been implicated in a number of HSP subtypes. Mutations in the 23 known autosomal recessive HSP genes explain less than half of autosomal recessive HSP cases. To identify novel autosomal recessive HSP disease genes, exome sequencing was performed in 79 index cases with autosomal recessive forms of HSP. Resulting variants were filtered and intersected between families to allow identification of new disease genes. We identified two deleterious mutations in the phospholipase DDHD2 gene in two families with complicated HSP. The phenotype is characterized by early onset of spastic paraplegia, mental retardation, short stature and dysgenesis of the corpus callosum. Phospholipase DDHD2 is involved in intracellular membrane trafficking at the golgi/ endoplasmic reticulum interface and has been shown to possess phospholipase A1 activity in vitro. Discovery of DDHD2 mutations in HSP might therefore provide a link between two key pathogenic themes in HSP: membrane trafficking and lipid metabolism.     

Screening of patients with hereditary spastic paraplegia reveals seven novel mutations in the SPG4 (Spastin) gene

Hereditary spastic paraplegia (HSP) is a heterogeneous condition characterised in its pure form by progressive lower limb spasticity. Mutations in SPG4 (encoding spastin) may be responsible for up to 40% of autosomal dominant (AD) cases. A cohort of 41 mostly pure HSP patients from Britain and Austria, 30 of whom displayed AD inheritance, was screened for mutations in SPG4 by single strand conformation polymorphism (SSCP) analysis followed by sequencing of samples with mobility shifts. We identified eight SPG4 mutations in pure AD HSP patients, seven of which were novel: one missense mutation within the AAA cassette (1633G>T), two splice site mutations (1130-1G>T, 1853+2T>A) and four frameshift mutations (190_208dup19, 1259_1260delGT, 1702_1705delGAAG, 1845delG). A novel duplication in intron 11 (1538+42_45dupTATA) was also detected. We report the HUGO-approved nomenclature of these mutations as well. Furthermore, we detected a silent change (1004G>A; P293P), previously reported as a mutation, which was also present in controls. The frequency of SPG4 mutations detected in pure AD HSP was 33.3%, suggesting that screening of such patients for SPG4 mutations is worthwhile. Most patients will have unique mutations. Screening of SPG4 in apparently isolated cases of HSP may be of less value.