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.     

Alzheimer病患者线粒体DNA点突变的研究

目的旨在观察Alzheimer病(Alzheimerdisease,AD)患者线粒体DNA(mitochondrialDNA,mtDNA)上点突变的情况,并探讨mtDNA点突变与AD发生的关联性。方法入组了111例AD患者作为AD组和性别/年龄与之相匹配的正常老人117名组成对照组,应用PCR-RFLP的方法对被研究对象mtDNA上分别位于第4336、5460和8021三个位置的点突变情况进行检测。结果第4336位置上的碱基未发现存在突变的现象。第8021位置上的碱基仅在正常老人组内检测到1例突变型,其余均为野生型。在第5460位置上对照组突变率为2.6%(3/117),AD老人组中突变率为6.3%(7/111),显著性检验χ2=1.902,P=0.168。结论在我国上海汉族人群中线粒体DNA上第4336位置上可能不存在点突变的现象,第8021位置上突变也很少发生,在第5460位置上的碱基可能出现A或T的点突变,但这种突变的发生可能与AD的发生无直接关联。     

中国肾上腺脑白质营养不良患者中一个新的ABCD1基因突变的鉴定

目的鉴定并分析1个新的肾上腺脑白质营养不良家系的基因突变类型和位点.方法采用长链RT-PCR技术,从外周血提取总RNA并合成cDNA,以cDNA为模板,分4个片段扩增致病基因编码区,将纯化后的PCR产物直接测序,找出基因突变的位点.同时应用限制性酶切分析的方法,分析发病家系所有成员的基因组DNA,以证实所发现的突变.结果患者肾上腺脑白质营养不良基因外显子2上的第343位密码子发生了GGC→GTC改变,使原来编码的甘氨酸被缬氨酸(G343V)取代;患者母亲为G343V突变携带者,患者哥哥的基因型和患者完全相同,其父亲为正常基因型.结论在中国人肾上腺脑白质营养不良患者中发现一个新的ABCD1基因突变,即G343V突变.     

伴皮质下梗死及白质脑病常染色体显性遗传性脑动脉病的NOTCH3基因诊断

目的 分析伴皮质下梗死及白质脑病常染色体显性遗传性脑动脉病((CADASIL)的NOTCH3基因突变类型.方法 对临床诊断为CADASIL的4例先证者、来自3个家系10例患者及4例无类似临床表现成员、以及100名健康对照者进行NOTCH3基因PCR扩增及变性高压液相色谱分析(DHPLC)检测;对DHPLC阳性结果进行DNA双向测序,明确致病性突变或多态类型.结果 在CADASIL先证者及其家系患者中共发现134半胱氨酸→酪氨酸(Cys134Tyr)、141精氨酸→半胱氨酸(Arg141Cys)、90精氨酸→半胱氨酸(Arg90Cys)3种突变类型,存在于第3、第4外显子,为杂合错义突变.同时发现15种多态类型.其中家系1和家系2中分别发现1名成员与先证者存在相同位点的NOTCH3基因致病性突变,尚未出现与先证者相应的临床表现,被确定为临床前期患者.结论 NOTCH3单基因突变是CADASIL的分子遗传学基础,第3、4外显子可能是中国CADASIL家系的热点突变区.第4外显子Cys134Tyr突变类型为国内首次报告.     

早发性帕金森病parkin基因的突变分析

目的　探讨中国早发性帕金森病 (PD)患者 parkin基因第 3～ 7外显子是否存在缺失突变及其与该病临床特点的关系。方法　采集 33例早发性PD患者外周血液 ,提取DNA ,通过PCR扩增、琼脂糖凝胶电泳鉴定 parkin基因第 3～ 7外显子缺失突变 ,并结合临床资料分析。 结果　 33例早发性PD患者中发现 2例有第 7外显子缺失 ,1例有第 5、7外显子联合缺失 ,发生缺失突变患者起病年龄分别为 46、48、5 0岁 ,临床表现为震颤、僵直和运动迟缓 ,但无异动症。第 3、4、6外显子未发现缺失突变。结论　中国早发性PD患者中存在 parkin基因第 5、7外显子缺失突变改变。     

视神经脊髓炎外显子组学的初步研究

目的通过外显子组学测序筛查视神经脊髓炎(neuromyelitis optica,NMO)的基因突变位点,为进一步确定NMO的易感基因积累资料。方法收集散发性NMO患者4例,取其外周血后提取DNA,基于IlluminaHiSeq平台进行全外显子高通量测序,旨在发现患者中共有的基因突变位点。结果 4例患者中共存在33个共有突变位点,其中9个单核苷酸突变和24个小片段插入缺失突变,涉及29个基因。结论 4例NMO患者中共发现33个共有突变位点,涉及29个基因。     

180例散发性神经变性病引起的痴呆朊蛋白基因突变的研究

目的对180例散发性神经变性病引起的痴呆患者进行朊蛋白基因（PRNP）突变的筛查,探讨PRNP基因突变在临床诊断的神经变性病痴呆中的发生情况以及可能的原因。方法研究180例散发性痴呆患者和310例健康对照的PRNP基因的开放阅读框架进行PCR扩增,产物直接测序,异常者重复测序,并与对照组对比。结果共发现4个不同的PRNP基因杂合突变,分别为$97N、F198V、R208C和M232R,突变率2．22％,结合患者的临床表型,以及未在310个正常人中发现突变,考虑这4例突变可能为病理性突变。结论4例突变中有3例为新突变,4例突变均可能与痴呆的发生相关。     

晚期婴儿型神经元蜡样质脂褐素沉积病患者临床特点和基因改变

目的总结临床病理诊断为晚期婴儿型神经元蜡样质脂褐素沉积病(LINCL)患者的临床特点和基因改变。方法总结分析9例LINCL患者(其中3例为文献报道的患者)的临床特点,并对其中4例患者进行CLN2基因检测。结果癫痫是我国LINCL患者最主要的首发临床症状,其发作表现形式多样。CLN2基因检查结果显示,在两例患者分别发现位于第3内含子的IVS3-1G→A剪接突变和第6外显子的G217V杂合突变以及第13外显子的S538Y纯合突变,上述突变均为文献尚未报道过的新突变,在50名健康人中未发现这些基因突变。另两例患者CLN2基因检查正常。结论我国LINCL患者癫痫发作具有多种表现形式,肌阵挛癫痫不常见。我国CLN2基因的突变类型与其他国家或地区可能不同,也可能存在新的基因。     

结节性硬化症TSC2基因5238-5255 del 18 bp及2713 C>T基因突变分析

目的检测并分析2例中国汉族结节性硬化症(tuberous sclerosis complex,TSC)患者TSC2基因突变特点。方法采用直接测序法对31个家系的34例TSC患者及其父母33名进行TSC1基因和TSC2基因全长编码外显子基因检测。测序后发现第25家系先证者为TSC2基因外显子40的框内移码突变5238-5255 del 18 bp,第11家系先证者为TSC2基因外显子23错义突变Arg905Trp。进一步采用变性凝胶电泳及内切酶技术在患者与120名正常对照中检测这两种突变。结果第25家系先证者外显子40出现5238-5255d el CATCAAGCGGCTCCGCCA突变,导致6个氨基酸缺失的框内移码突变(1746-1751del His-Ile-Lys-Arg-Leu-Gly),第11家系先证者外显子23出现2713 C>T(Arg905Trp)错义突变,2713位碱基由胞嘧啶(C)改变为胸腺嘧啶(T),导致第905位氨基酸精氨酸被色氨酸替代。120名正常对照未检测到这两种突变。结论TSC2基因5238-5255 del 18 bp及2713 C>T突变为两种致病性突变。     

痴呆患者早老素-1基因第6号外显子突变研究

目的探讨痴呆患者早老素-1基因第6号外显子的突变特点。方法应用聚合酶链反应一单链构象多态性(PCR-SSCP)和DNA测序技术检测53例SAD患者、60例VD患者及90名健康老年人早老素-1基因第6号外显子。结果DNA测序在SSCP泳动异常标本中发现1123位点和1300位点发生错义突变，其中，SAD组2例在1123位点发生突变、2例在1300位点突变，VD组1例在1123位点发生突变；1123位点发生C→G突变(cys23Trp)，1300位点发生A→C突变(Asp 200Ala)。结论SAD患者存在早老素-1基因第6号外显子突变，本实验结果显示的2个突变位点均处在早老素蛋白的重要功能区，考虑此突变为病理性突变。     

The G209A mutation in the alpha-synuclein gene in Brazilian families with Parkinson's disease

A missense G209A mutation of the alpha-synuclein gene was recently described in a large Contursi kindred with Parkinson's disease (PD). The objective of this study is to determine if the mutation G209A of the alpha-synuclein gene was present in 10 Brazilian families with PD. PD patients were recruited from movement disorders clinics of Brazil. A family history with two or more affected in relatives was the inclusion criterion for this study. The alpha-synuclein G209A mutation assay was made using polymerase chain reaction and the restriction enzyme Tsp45I. Ten patients from 10 unrelated families were studied. The mean age of PD onset was 42.7 years old. We did not find the G209A mutation in our 10 families with PD. Our results suggest that alpha-synuclein mutation G209A is uncommon in Brazilian PD families.     

A founding LRRK2 haplotype shared by Tunisian, US, European and Middle Eastern families with Parkinson's disease

The Leucine-rich repeat kinase 2 (LRRK2) gene has been identified as a disease susceptibility gene for Parkinson's disease (PD), with G2019 (6055G>A) being the most frequent mutation. This mutation was present in 42% (38/91) of Tunisian families and 2% (1/39) of US families we have studied. A founding haplotype was identified in our data and it is shared by families from Tunisia, US, European and Middle Eastern countries. The most recent common founder of the mutation was dated to 2600 (95% CI: 1950-3850) years ago although additional studies are warranted to ensure an accurate age estimate for this mutation.     

SPG3A mutation screening in English families with early onset autosomal dominant hereditary spastic paraplegia

Mutations in the SPG3A gene encoding the novel GTPase atlastin have recently been implicated in causing autosomal dominant hereditary spastic paraplegia (ADHSP) in six unrelated families. The phenotype of affected individuals in all cases has been of an early onset uncomplicated form of the disease. One particular missense mutation, R239C, in exon 7 of SPG3A has been identified in three of these families. We performed mutation screening by direct sequencing of all 14 exons and flanking sequences of the SPG3A gene in affected individuals from 12 unrelated English families, all with an early onset uncomplicated ADHSP in whom spastin mutations had previously been excluded. The R239C mutation was found to co-segregate with the disease in one English ADHSP family confirming a widespread prevalence for this commonly occurring mutation. No additional SPG3A mutations were identified in the remaining 11 families suggesting that even within this specific sub-set of early onset uncomplicated ADHSP patients atlastin mutations are relatively rare.     

Parkinson's disease due to the R1441G mutation in Dardarin: a founder effect in the Basques.

The recent discovery of mutations in Dardarin (LRRK2) have been related to the appearance of Parkinson's disease in several families. Notably, one single mutation in this gene (R1441G) not only appeared in familial, but also in apparently sporadic Parkinson disease (PD) patients of Basque descent. A clinical population was ascertained, and subjects were classified into Basque and non-Basque descent according to their known ancestry. The R1441G mutation was assayed using an allele-specific polymerase chain reaction, and several single nucleotide polymorphisms surrounding this mutation were analyzed by direct sequencing. In addition to 22 members of the original Basque families where R1441G was identified, we observed 17 carriers of the mutation who were apparently related through a common ancestor. From a clinical perspective, the disease observed in mutation carriers is indistinguishable from that in noncarriers. The R1441G mutation causes a form of Parkinson's disease that is equivalent to that observed in idiopathic Parkinson's disease. This mutation appears in 16.4% and 4.0% of familial and sporadic PD in this Basque population, respectively.     

Failure to find mutations in ubiquitin carboxy-terminal hydrolase L1 gene in familial Parkinson's disease

Recently, a missense mutation (Ile93Met) of exon 4 in the ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) gene was identified in a German family with autosomal dominant Parkinson's disease (ADPD). To determine whether this mutation is responsible for familial Parkinson's disease (PD), we sequenced the entire coding region of UCH-L1 gene in nine families with ADPD. No mutations in this gene were found in any of the families studied. We conclude that the Ile93Met mutation in UCH-L1 gene is a very rare cause of familial PD.     

Creutzfeldt-Jakob disease cosegregates with the codon 178Asn PRNP mutation in families of European origin.

We recently discovered an amino acid-altering heterozygous mutation in codon 178 of the PRNP amyloid precursor gene in patients with familial Creutzfeldt-Jakob disease. This mutation is now shown to be associated with the occurrence of disease in 7 unrelated families of Western European origin, among which a total of 65 members are known to have died from Creutzfeldt-Jakob disease. The mutation was detected in each of 17 tested patients, including at least 1 affected member of each family, and in 16 of 36 of their first-degree relatives, but not in affected families with other mutations, patients with the nonfamilial form of the disease, or 83 healthy control individuals. Linkage analysis in two informative families yielded a lod score of 5.30, which, because no recombinants were found, strongly suggests that codon 178Asn is the actual disease mutation.     

Mutation analysis of the small heat shock protein 27 gene in chinese patients with Charcot-Marie-Tooth disease

BACKGROUND: Charcot-Marie-Tooth (CMT) disease, the most common hereditary peripheral neuropathy, is highly clinically and genetically heterogeneous, and mutations in at least 18 genes have been identified. Recently, mutations in small heat shock protein 27 (Hsp27) were reported to cause CMT disease type 2F and distal hereditary motor neuropathy. OBJECTIVE: To investigate the frequency and phenotypic features of an Hsp27 mutation in Chinese patients with CMT disease. DESIGN: DNA samples from 114 unrelated patients with CMT disease were screened for mutations in Hsp27 by polymerase chain reaction and direct sequencing. A cosegregated study was performed using the MbiI restriction endonuclease, and 50 healthy control subjects were analyzed. Haplotype analysis was performed using 5 short tandem repeat markers to analyze whether the families with the same mutation probably had a common ancestor. RESULTS: One missense mutation, C379T, was detected in 4 autosomal dominant families with CMT disease type 2, and haplotype analysis indicated that the 4 families probably had a common founder. The frequency of the Hsp27 mutation is 0.9% (1/111) in Chinese patients with CMT disease in our study, and the phenotypes were characterized by later onset (age, 35-60 years) and mild sensory impairments. Electrophysiological findings showed moderately to severely slowed nerve conduction velocities in lower limb nerves but normal or mildly reduced velocities in upper limb nerves. CONCLUSIONS: To our knowledge, this is the first report of an Hsp27 mutation in the People's Republic of China. The C379T mutation in Hsp27 also causes CMT disease type 2, except for distal hereditary motor neuropathy, and the phenotypes are distinct from the family with CMT disease type 2F described previously. A mutation of Hsp27 may be uncommon in Chinese patients with CMT disease.     

Linkage exclusion in French families with probable Parkinson' s disease.

We analyzed the segregation of genetic markers spanning chromosomal regions 2p13, 4p14-15, 4q21-23, 6q25-27, and 17q21 in nine French families affected by autosomal-dominant probable Parkinson's disease. These regions have been linked or associated with familial Parkinson's disease. Multipoint linkage and haplotype analyses excluded 2p13 and 4p14-15 loci in five of nine families. For three families, which were equivocal for two-point linkage at D4S405, the ubiquitin carboxy-terminal hydrolase gene (UCH-L1) was sequenced. In one family, a novel UCH-L1 M124L mutation that did not segregate with early-onset disease was identified. This suggests that rare variants in this gene may not be pathogenic. In seven of nine families, it could be inferred that affected individuals did not share 4q21-23 (alpha-synuclein) haplotypes. All families were unequivocally excluded by haplotype analysis from the parkin locus on 6q25-27. Finally, the 17q21 region was excluded in four of nine families, and no mutation in the tau gene was identified in the five remaining families. Findings from this study confirm genetic heterogeneity within familial parkinsonism.     

The role of the α-synuclein gene mutation in patients with sporadic Parkinson's disease in the United Kingdom

Parkinson's disease is a common neurodegenerative disorder ofunknown aetiology. A pathogenic point mutation within the α-synuclein gene has recently been identified in one Italian-American kindred andthree families of Greek origin with parkinsonism. DNA from 70 patientswith Parkinson's disease was screened for this G209A mutation. Nosamples were positive for the mutation, suggesting that it is notrelevant for most patients with sporadic idiopathic Parkinson's disease.

     

Founder effect for the Ala431Glu mutation of the presenilin 1 gene causing early-onset Alzheimer’s disease in Mexican families

The etiology of Alzheimer’s disease (AD) is complex. To date, molecular genetic studies in several families affected with AD have identified three genes associated with highly penetrant early-onset AD: Presenilin 1 (PSEN1), Presenilin 2 (PSEN2) and β-amyloid precursor protein (APP); and one gene (apolipoprotein E) associated with late-onset AD. Molecular analysis of the PSEN1 gene was performed by direct sequencing of genomic DNA. The possible founder effect was investigated analyzing two highly polymorphic microsatellite markers flanking the PSEN1 gene. Twelve unrelated Mexican families with early-onset AD were analyzed. The Ala431Glu mutation in exon 12 of PSEN1 was found in nine (75%) of these families, which segregated showing autosomal dominant inheritance. Because all families bearing the mutation are from the State of Jalisco (located in Western Mexico), a founder effect was hypothesized. Microsatellite haplotype analysis suggested a common ancestor in these nine kindreds. In conclusion, the Ala431Glu mutation is a prevalent cause of early-onset familial Alzheimer’s disease in families from the State of Jalisco, Mexico. Genetic evidence supports that it is a founder mutation descending from a single common ancestor. These findings have important implications for prompt diagnosis and genetic counseling for Mexican patients with familial AD from Jalisco.A summary of the results of this study was presented at the Congress of the Human Genome Organization (HUGO, April, 2003). Workshop Abstract No 11: pp 14.