一个遗传性共济失调7型家系的基因突变分析

目的 研究1个遗传性共济失调7型回族家系的临床表现与基因突变特点.方法 应用聚合酶链反应、分子克隆及测序等方法对1个临床诊断为遗传性共济失调的回族家系进行SCA7基因检测,对异常片段进行分子克隆测序.结果 证实该家系为遗传性共济失调7型家系,视网膜退行性变为其相对独特的临床表现.先证者父亲异常片段CAG重复为46次;先证者异常片段CAG重复次数为54次,发病年龄较父代提前22年.结论 报告1个遗传性共济失调7型回族家系,该亚型明显的遗传早现及病程进展与CAG重复次数的不稳定扩增相关.     

安徽入亨廷顿病CAG三核苷酸重复的分子分析

为在分子水平了解安徽人亨廷顿病(HD)的发病机制,为该病的基因诊断和遗传咨询提供科学依据.应用巢式PCR,变性聚丙烯酰胺凝胶电泳以及DNA测序等方法,对6例正常安徽人以及6例HD家系的研究结果表明中国人正常IT15基因(CAG)n重复序列的拷贝数为13-26,而所有被分析的HD患者都携带一个CAG序列高度重复的IT15基因,其(CAG)n的拷贝数为40-94;且CAG重复序列的拷贝数与发病年龄呈现一定的相关性.     

一个遗传性共济失调3型家系中致病ATXN3中间类型等位基因分析

目的 研究遗传性共济失调3型中间类型等位基因致病表型的临床表现与基因突变特点.方法 应用PCR、毛细微管电泳、分子克隆及测序等方法 对1个临床诊断为遗传性共济失调家系进行ATXN3基因检测,对异常片段进行分子克隆测序.结果 证实该家系为遗传性共济失调3型家系,先证者异常片段CAG重复次数为43次;患者两个儿子异常片段重复分别为41、64次.结论 中间类型等位基因在两代间遗传是不稳定的,重复次数的改变是双向的,43次CAG重复是目前报道的遗传性共济失调3型发病患者最小不稳定重复次数.本家系的研究结果 进一步缩短了正常CAG重复次数与异常重复次数之间的差距.     

一个遗传性共济失调3型家系中致病ATXN3中间类型等位基因分析

目的 研究遗传性共济失调3型中间类型等位基因致病表型的临床表现与基因突变特点.方法 应用PCR、毛细微管电泳、分子克隆及测序等方法 对1个临床诊断为遗传性共济失调家系进行ATXN3基因检测,对异常片段进行分子克隆测序.结果 证实该家系为遗传性共济失调3型家系,先证者异常片段CAG重复次数为43次;患者两个儿子异常片段重复分别为41、64次.结论 中间类型等位基因在两代间遗传是不稳定的,重复次数的改变是双向的,43次CAG重复是目前报道的遗传性共济失调3型发病患者最小不稳定重复次数.本家系的研究结果 进一步缩短了正常CAG重复次数与异常重复次数之间的差距.     

一个遗传性共济失调3型家系中致病ATXN3中间类型等位基因分析

目的 研究遗传性共济失调3型中间类型等位基因致病表型的临床表现与基因突变特点.方法 应用PCR、毛细微管电泳、分子克隆及测序等方法 对1个临床诊断为遗传性共济失调家系进行ATXN3基因检测,对异常片段进行分子克隆测序.结果 证实该家系为遗传性共济失调3型家系,先证者异常片段CAG重复次数为43次;患者两个儿子异常片段重复分别为41、64次.结论 中间类型等位基因在两代间遗传是不稳定的,重复次数的改变是双向的,43次CAG重复是目前报道的遗传性共济失调3型发病患者最小不稳定重复次数.本家系的研究结果 进一步缩短了正常CAG重复次数与异常重复次数之间的差距.     

安徽人亨廷顿病CAG三核苷酸重复的分子分析

为在分子水平了解安徽人亨廷顿病（HD）的发病机制，为该病的基因诊断和遗传咨询提供科学依据。应用巢式PCR，变性聚丙烯酰胺凝胶电泳以及DNA测序等方法。对6例正常安徽人以及6例HD家系的研究结果表明：中国人正常IT15基因（CAG）n重复序列的拷贝数为13-26，而所有被分析的HD患者都携带一个CAG序列高度重复的IT15基因克勤克俭 （CAG）n的拷贝数为40-94；且CAG重复序列的拷贝数与发病年龄瓿现一定的相关性。     

2个亨廷顿舞蹈病家系动态突变及mtDNA D环高变区的检测

目的探讨mtDNA D环高变区突变与亨廷顿舞蹈病(HD)的关系。方法 PCR-DNA测序法检测2个HD家系(CAG)n重复序列、mtDNA D环高变区大片段缺失或插入突变。结果两家系正常人(CAG)n≤18次,患者n≥40次,mtDNA D环未见大片段缺失和插入。结论检测亨廷顿(IT15)基因(CAG)n可准确、快速诊断HD;mtDNA调控区大片段重组可能不是HD发病机制中的重要因素。     

脊髓小脑性共济失调12型维吾尔族一家系的基因突变及临床特点

目的 研究新疆地区维吾尔族脊髓小脑性共济失调12亚型(spinocerebellar ataxia type 12,SCA12)致病基因的CAG三核苷酸病理重复次数范围及临床特点.方法 依据Harding标准,收集一个维吾尔族家系,应用聚合酶链反应、琼脂糖凝胶电泳、T载体分子克隆技术并结合酶切鉴定、直接测序等技术对其中6例患者、54例家系"健康"个体进行分子遗传学诊断,基因诊断为SCA12型,同时对致病基因CAG三核苷酸病理重复次数进行突变分析.结果 发现该家系SCA12型患者6例,症状前患者13例.5例经基因重组检测发现:患者异常等位基因CAG重复数目分别是47次、51次、52次、53次;症状前患者是48次;其中在连续CAG重复中间有单个碱基C、A、G的互相替换.结论 SCA12型的47次CAG病理重复次数为国内外报道的最小CAG病理重复次数;国内首次对维吾尔族SCA12型的基因突变特点进行分析,从而对于该类疾病的准确分类、病因探讨、治疗、产前诊断等具有重要的意义.     

脊髓小脑性共济失调12型维吾尔族一家系的基因突变及临床特点

目的 研究新疆地区维吾尔族脊髓小脑性共济失调12亚型(spinocerebellar ataxia type 12,SCA12)致病基因的CAG三核苷酸病理重复次数范围及临床特点.方法 依据Harding标准,收集一个维吾尔族家系,应用聚合酶链反应、琼脂糖凝胶电泳、T载体分子克隆技术并结合酶切鉴定、直接测序等技术对其中6例患者、54例家系"健康"个体进行分子遗传学诊断,基因诊断为SCA12型,同时对致病基因CAG三核苷酸病理重复次数进行突变分析.结果 发现该家系SCA12型患者6例,症状前患者13例.5例经基因重组检测发现:患者异常等位基因CAG重复数目分别是47次、51次、52次、53次;症状前患者是48次;其中在连续CAG重复中间有单个碱基C、A、G的互相替换.结论 SCA12型的47次CAG病理重复次数为国内外报道的最小CAG病理重复次数;国内首次对维吾尔族SCA12型的基因突变特点进行分析,从而对于该类疾病的准确分类、病因探讨、治疗、产前诊断等具有重要的意义.     

家族性亨廷顿病临床和(CAG)n多态性分析

亨廷顿病 (Huntington’sdisease,HD)是一种常染色体显性遗传的基底节和大脑皮层变性疾病 ,临床特征为慢性进行性的舞蹈样动作和痴呆。 1993年 ,分离获得HD相关基因IT15 ,并确定其开放阅读框架 5’端多态性CAG三核苷酸重复序列的过度扩展为致病的突变[1] ,正常人群 (CAG)n拷贝数为 11- 34个。通过检测CAG拷贝数 ,可从基因水平确诊HD。基于此 ,我们对一个家族性HD家系两个病例进行了基因分析。资料与方法1 临床资料 :先证者男性 ,6 6岁。以“四肢不自主运动14年 ,饮水呛咳 1个月”为主诉入院。来诊 14年前曾诊为“HD”。 4年前出现…     

中国人亨廷顿病CAG三核苷酸重复的分子分析

为在分子水平了解中国人亨廷顿病的发病机理，为该病的基因诊断和遗传咨询提供科学依据，应用巢式ＰＣＲ、变性聚丙烯酰胺凝胶电泳以及ＤＮＡ测序等方法，对正常中国人及亨廷顿病（Ｈｕｎｔｉｎｇｔｏｎ＇ｓｄｉｓｅａｓｅ，ＨＤ）患者的ＩＴ１５基因（ＣＡＧ）ｎ重复序列的拷贝数进行了分析。４０例正常中国人以及１３个ＨＤ家系的研究结果表明：中国人正常ＩＴ１５基因（ＣＡＧ）ｎ重发序列的拷贝数为１３～２６，多数为１６；而所有被分析的ＨＤ患者都携带一个ＣＡＧ序列高度重复的ＩＴ１５基因，其（ＣＡＧ）ｎ的拷贝数为４０～９４；且ＣＡＧ重复序列的拷贝数与发病年龄呈现一定的相关性。正常和ＨＤ等位基因之间的（ＣＡＧ）ｎ拷贝数不相重叠，在１０３例高风险ＨＤ家庭成员的症状前诊断中，根据（ＣＡＧ）ｎ拷贝数的测定，发现了３５例ＨＤ基因携带者，结果表明，ＩＴ１５基因的不稳定突变是导致中国人亨廷顿病的遗传基础。     

A novel PCR-based approach for the detection of the Huntington disease associated trinucleotide repeat expansion

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder associated with expansions of an unstable CAG trinucleotide repeat in exon 1 of the IT15 gene. In normal individuals, IT15 contains up to 35 CAG repeats, while in affected the repeat length is >36. Polymerase chain reaction (PCR) is used to estimate the number of CAG repeats but may be inefficient in long repeats because of the high C+G content of the HD locus. We present a novel PCR approach for the diagnosis of HD, which permits direct visualization of the amplified products on agarose gel, using ethidium bromide. It is based on the methylation-sensitive conversion of C residues to U by bisulfite treatment of single-stranded DNA and subsequent amplification of the sense strand with specific primers. The bisulfite treatment dramatically reduces the C + G content of the region; thus, the high Tm and stable secondary structures are no longer obstacles to PCR. In both normal and affected individuals, UAG repeats (5'- CAG-3', before bisulfite treatment) in the sense strand can easily be amplified and visualized on a gel by ethidium bromide staining. The method has considerable advantages compared with other described PCR-based diagnostic tests for HD.     

Trinucleotide repeat length and progression of illness in Huntington''s disease.

The genetic defect causing Huntington's disease (HD) has been identified as an unstable expansion of a trinucleotide (CAG) repeat sequence within the coding region of the IT15 gene on chromosome 4. In 50 patients with manifest HD who were evaluated prospectively and uniformly, we examined the relationship between the extent of the DNA expansion and the rate of illness progression. Although the length of CAG repeats showed a strong inverse correlation with the age at onset of HD, there was no such relationship between the number of CAG repeats and the rate of clinical decline. These findings suggest that the CAG repeat length may influence or trigger the onset of HD, but other genetic, neurobiological, or environmental factors contribute to the progression of illness and the underlying pace of neuronal degeneration.     

Study of the Huntington''s disease (HD) gene CAG repeats in schizophrenic patients shows overlap of the normal and HD affected ranges but absence of correlation with schizophrenia.

The CAG repeats in the Huntington's disease gene were investigated in chromosomes from 71 unrelated schizophrenic persons and 18 patients with schizoaffective disorder in order to determine if any of these patients had abnormal expansions. All of the probands had repeat sizes in the normal range (< 35 repeats) and there was no significant difference between the allele distributions of these patients and the normal controls. The families of two patients with 32 repeats and one patient with 34 repeats were investigated further and showed no uniform segregation of the disease with the large repeat alleles. The proband with 34 repeats inherited a chromosome that originally had 36 repeats in her father. The presence of 36 CAG repeats in members of her family and in HD patients suggests that there is an overlap between the normal and Huntington's disease CAG repeat size ranges. The more recently described CCG polymorphism in this gene was also examined in the schizophrenic and schizoaffective persons. All patients had alleles in the normal range.     

Expression of the Huntington's disease (IT15) protein product in HD patients

Huntington's disease (HD) is an inherited, neurodegenerativedisorder caused by expansion of a CAG repeat in the IT15 gene,leading to an expanded glutamine repeat in the HD protein. Themechanism by which the expanded repeat causes expression ofthe disease is not known, though there do not appear to be changesin the mRNA levels. We have conducted quantitative Western blotanalyses of HD patients and controls. Expression of the IT15protein is essentially equal in control and HD frontal cortex.In caudate from HD patients, IT15 protein is decreased in parallelwith the decrease in a neuronal marker, suggesting that lossof IT15 protein is secondary to neuronal loss. In order to determineexpression of the two alleles of the IT15 protein we used Westernblots of 4% polyacrylamide gels. Both alleles of the IT15 proteinwere expressed at similar levels in HD lymphoblastoid cell linesand HD post-mortem hippocampus and cerebellum (regions relativelyspared in HD), indicating that even very long CAG repeats canbe translated into polyglutamine. In contrast, in cerebral cortexand caudate (regions severely affected in HD), in the longerexpanded repeat cases the expanded allele of the IT15 proteinwas present at a significantly lower level (compared with thenormal length allele), often with a smear of more slowly migratingreactivity above it. These data suggest the possibility of alteredstructure, abnormal processing or abnormality of protein—proteininteractions involving the IT15 protein with the expanded glutaminerepeat.     

CAG repeat length in the androgen receptor gene of infertile Japanese males with oligozoospermia

We analysed the CAG repeat length in exon 1 of the androgen receptor gene in 59 idiopathic Japanese infertile males with oligozoospermia; 36 fertile males were also analysed as controls. The number of CAG repeats in infertile males ranged from 14 to 32 (mean 21.2+/-4.2), whereas the number of CAG repeats in fertile males ranged from 16 to 31 (mean 21.4+/-3.5). Among infertile males, six possessed a short form of 14 CAG repeats and three possessed 15 CAG repeats. On the other hand, fertile males did not possess the short form of 14 or 15 CAG repeats. The incidence of infertile males with 14 and 15 CAG repeats was significantly higher (P<0.05) than that of fertile males. Although the sample size is small, the results suggest that the reduction of CAG repeats in exon 1 of the androgen receptor is closely related to impaired spermatogenesis in infertile Japanese males.