Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant inherited disorder characterized by degeneration of cerebellar Purkinje cells, spinocerebellar tracts, and selective brainstem neurons owing to the expansion of an unstable CAG trinucleotide repeat. To gain insight into the pathogenesis of the SCA1 mutation and the intergenerational stability of trinucleotide repeats in mice, we have generated transgenic mice expressing the human SCA1 gene with either a normal or an expanded CAG tract. Both transgenes were stable in parent to offspring transmissions. While all six transgenic lines expressing the unexpanded human SCA1 allele had normal Purkinje cells, transgenic animals from five of six lines with the expanded SCA1 allele developed ataxia and Purkinje cell degeneration. These data indicate that expanded CAG repeats expressed in Purkinje cells are sufficient to produce degeneration and ataxia and demonstrate that a mouse model can be established for neurodegeneration caused by CAG repeat expansions.
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PMID:SCA1 transgenic mice: a model for neurodegeneration caused by an expanded CAG trinucleotide repeat. 755 54

Spinocerebellar ataxia 2 (SCA2) is one of the loci for the clinically and genetically heterogeneous group of autosomal dominant type I cerebellar ataxias. After initial linkage to chromosome 12q in Cuban families, SCA2 was shown to be the gene responsible for the disease in Italian, Tunisian, French-Canadian, Austrian-Canadian and Martinican kindreds with dominant ataxia, and the candidate interval was reduced to 6.4 cM between markers D12S84 and D12S79. Comparison of patients from families of different geographical origins clearly demonstrates the clinical interfamilial variability of the clinical signs which reaches statistical significance for the frequency of extrapyramidal rigidity, postural tremor and dementia. The most striking difference between the 29 Martinican SCA2 patients and those with SCA1 on chromosome 6p or SCA3/MJD on chromosome 14q is the greater frequency of hyporeflexia in the former. A mean 12.5 year anticipation is observed, with a more rapid clinical course of the disease in successive generations, indicating that an expanded trinucleotide repeat probably constitutes the underlying molecular mechanism.
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PMID:Autosomal dominant cerebellar ataxia type I linked to chromosome 12q (SCA2: spinocerebellar ataxia type 2). 761 88

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant progressive neurodegenerative disorder characterized by ataxia, dysarthria, ophthalmoparesis, and variable degrees of amyotrophy and neuropathy. Symptoms usually develop in the third or fourth decade but anticipation has been noted in juvenile onset cases. Neuropathologic findings include severe neuronal loss in the cerebellum and brainstem as well as degeneration of spinocerebellar tracts. The SCA1 gene which maps to the short arm of human chromosome 6 was identified using a positional cloning approach. The disease causing mutation is an expansion of a CAG trinucleotide repeat which lies within the coding region of a novel protein, ataxin-1, and encodes a polyglutamine tract. The number of CAG repeats varies from 6-39 repeats on normal alleles and 40-81 repeats on SCA1 alleles. The repeat has a perfect CAG configuration on expanded alleles whereas it is interrupted by 1-3 CAT units on normal alleles. Both wild type and expanded alleles are transcribed, ruling out impairment of transcriptional efficiency in SCA1. A pathogenetic model is proposed based on the findings in SCA1 and other neurodegenerative diseases caused by expansion of polyglutamine tracts. The expanded polyglutamine tract in ataxin-1 may lead to neurodegeneration through a gain of function mechanism involving aberrant interactions with other molecules in the involved neurons.
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PMID:Spinocerebellar ataxia type 1. 761 95

Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disorder characterized by ataxia, dysarthria and progressive bulbar dysfunction. The SCA 1 gene which maps to the short arm of chromosome 6 has been isolated using a positional cloning approach. The SCA1 transcript is 10660 bases and encodes a novel protein, ataxin-1, with a predicted molecular weight of 87 kDa. Expansion of a CAG repeat localized near the amino terminus of ataxin-1 has been found to be the mutational mechanism in SCA1. This CAG repeat is highly polymorphic with normal alleles containing 6-39 repeats. Individuals affected with SCA1 have one normal allele and one expanded allele containing 40-81 repeats. The size of the repeat correlates inversely with the age of onset of symptoms and the severity of disease. The repeat is a continuous CAG repeat tract on SCA1 chromosomes whereas in > or = 98% of normal alleles one or more CAT interruptions break the CAG repeat tracts into two tracts containing less than 18 repeats each. This suggests that loss of CAT interruptions within the SCA1 CAG repeat on normal chromosomes leads to triplet instability.
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PMID:Spinocerebellar ataxia type 1. 762 Jan 19

Spinocerebellar ataxia type 1 and Machado-Joseph disease are two autosomal dominant cerebellar ataxias caused by expansions of unstable CAG repeats in the coding region of the causative genes. The selectivity of cell death and the resulting characteristic neuropathological features in each of these diseases are not explained by the gene expression patterns. Since the repeat size correlates with age at onset and severity of these diseases, somatic mosaicism, the result of mitotic instability of the CAG repeat, could be the basis for specificity of neurodegeneration; brain structures with larger expanded repeats would be more severely affected. To study the association between neuropathological changes and somatic mosaicism of the CAG repeat size in the central nervous system of patients with these two ataxias, we determined the size of the (CAG)n expansion in 20 different regions of the brain, brainstem, cerebellum, and spinal cord from 3 patients with spinocerebellar ataxia type 1 and 3 with Machado-Joseph disease; these regions were selected for their differential neuropathological involvement in the two disorders. We observed a considerable homogeneity of repeat size ranges in all but 1 of the 20 regions examined: The cerebellar cortex showed slightly smaller (CAG)n tracts in all specimens from both groups of patients. Our results suggest that the pattern of repeat size mosaicism, similar in spinocerebellar ataxia type 1 and Machado-Joseph disease, reflects the developmental pathways and cell composition of different central nervous system regions and is not the cause of selective cell death in these disorders.
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PMID:Somatic mosaicism in the central nervous system in spinocerebellar ataxia type 1 and Machado-Joseph disease. 877 1

Sixty-five patients suffering from autosomal dominant cerebellar ataxia-I(ADCA-1) were subjected genotype phenotype correlation analysis using molecular genetic assignment to the spinocerebellar ataxia type 1, 2 or 3 (SCA1, -2 or -3) locus, clinical examination, eye movement recording and morphometric analysis of MRIs. Pyramidal tract signs, pale discs and dysphagia were more frequent in SCA1 compared SCA2 and SCA3 patients. Saccade velocity was reduced in 56% of SCA1 and all SCA2, but only in 30% of SCA3 patients. MRIs of SCA2 patients showed atrophy changes typical of severe olivopontocerebellar atrophy (OPCA). The morphological changes in SCA1 were similar but less pronounced. In contrast, SCA3 patients had only mild cerebellar and brain stem atrophy distinct from typical OPCA. The principal finding of this study is that mutations of the SCA2 and SCA3 gene cause phenotypes which can be distinguished in vivo by recording of eye movements and morphometric MRI analysis. Correlative plotting of saccade velocity and diameter of the middle cerebellar peduncle yields a clear separation of SCA2 and SCA3. Spinocerebellar ataxia type I falls into an intermediate range that overlaps with both SCA2 and SCA3. However, the clinical syndrome observed in SCA1 patients is different from that in SCA2 and SCA3.
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PMID:Autosomal dominant cerebellar ataxia type I clinical features and MRI in families with SCA1, SCA2 and SCA3. 893 75

Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited progressive neurological disorder characterized by neuronal degeneration and reactive gliosis in the cerebellum, brainstem, spinocerebellar tracts, and dorsal columns. Multiple system atrophy is a sporadic progressive neurological disorder with degeneration and gliosis in the basal ganglia, cerebellum, brainstem, and spinal autonomic nuclei, and with argyrophilic glial cytoplasmic inclusions. We describe 4 members of a family with the SCA1 mutation and a dominantly inherited progressive ataxia in which autopsy examination of 1 member showed neuropathological changes typical of multiple system atrophy, including glial cytoplasmic inclusions. In this patient, magnetic resonance imaging revealed marked brainstem and cerebellar volume loss and mild supratentorial generalized volume loss. Positron emission tomography with [18F]fluorodeoxyglucose revealed widespread hypometabolism in a pattern found in sporadic multiple system atrophy and not in dominantly inherited olivopontocerebellar atrophy. Positron emission tomography with [11C]flumazenil revealed normal benzodiazepine receptor distribution volumes, similar to those seen in sporadic multiple system atrophy. Two other family members still living had similar changes in the imaging studies. The findings in this family suggest that the SCA1 gene mutation can result in a disorder similar to multiple system atrophy, both clinically and neuropathologically.
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PMID:Spinocerebellar ataxia type 1 with multiple system degeneration and glial cytoplasmic inclusions. 896 56

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant neurological disorder caused by the expansion of a CAG repeat encoding a polyglutamine tract. Work presented here describes the behavioral and neuropathological course seen in mutant SCA1 transgenic mice. Behavioral tests indicate that at 5 weeks of age mutant mice have an impaired performance on the rotating rod in the absence of deficits in balance and coordination. In contrast, these mutant SCA1 mice have an increased initial exploratory behavior. Thus, expression of the mutant SCA1 allele within cerebellar Purkinje cells has divergent effects on the motor behavior of juvenile animals: a compromise of rotating rod performance and a simultaneous enhancement of initial exploratory activity. With age, these animals develop incoordination with concomitant progressive Purkinje neuron dendritic and somatic atrophy but relatively little cell loss. Therefore, the eventual development of ataxia caused by the expression of a mutant SCA1 allele is not the result of cell death per se, but the result of cellular dysfunction and morphological alterations that occur before neuronal demise.
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PMID:Purkinje cell expression of a mutant allele of SCA1 in transgenic mice leads to disparate effects on motor behaviors, followed by a progressive cerebellar dysfunction and histological alterations. 929 84

Spinocerebellar ataxia type 1 (SCA 1) is an autosomal dominant disorder characterized by neurodegeneration of the cerebellum, spinal cord and brainstem. This neurodegeneration disease is associated with expansion of unstable CAG repeats within the coding region of the gene. We are conducting a local survey of the normal population and candidate patients to analyze the CAG repeats in SCA 1 gene. So far, we have collected peripheral blood from 78 normal individuals and 10 patients with dominant inherited ataxia disorders, and assayed the SCA1 CAG trinucleotide repeat using genomic polymerase chain reaction (PCR). Even though no local SCA 1 patients have been identified, we have established the distributions of the CAG repeat units of SCA 1 gene in the normal population in Taiwan. The normal range of CAG repeats is from 22 to 33 repeats, with the most common being 30 repeats. The range is relatively narrow compared to that reported for other ethnic groups. In addition, direct genomic PCR analysis of the SCA 1 gene from villous DNA has been successful in our laboratory. Screening of SCA 1 patients from patients with dominant inherited ataxia is currently underway in our laboratory. Here, we demonstrate that our molecular analysis technique makes possible the quick and accurate diagnosis of SCA1 patients and prenatal screening for SCA 1 families.
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PMID:The CAG repeats number of spinocerebellar ataxia type 1 gene in normal Taiwanese and in patients with dominant inherited ataxia. 930 71

Spinocerebellar ataxia type 1 (SCA1) is one of several neurodegenerative disorders caused by an expansion of a polyglutamine tract. It is characterized by ataxia, progressive motor deterioration, and loss of cerebellar Purkinje cells. To understand the pathogenesis of SCA1, we examined the subcellular localization of wild-type human ataxin-1 (the protein encoded by the SCA1 gene) and mutant ataxin-1 in the Purkinje cells of transgenic mice. We found that ataxin-1 localizes to the nuclei of cerebellar Purkinje cells. Normal ataxin-1 localizes to several nuclear structures approximately 0.5 microm across, whereas the expanded ataxin-1 localizes to a single approximately 2-microm structure, before the onset of ataxia. Mutant ataxin-1 localizes to a single nuclear structure in affected neurons of SCA1 patients. Similarly, COS-1 cells transfected with wild-type or mutant ataxin-1 show a similar pattern of nuclear localization; with expanded ataxin-1 occurring in larger structures that are fewer in number than those of normal ataxin-1. Colocalization studies show that mutant ataxin-1 causes a specific redistribution of the nuclear matrix-associated domain containing promyelocytic leukaemia protein. Nuclear matrix preparations demonstrate that ataxin-1 associates with the nuclear matrix in Purkinje and COS cells. We therefore propose that a critical aspect of SCA1 pathogenesis involves the disruption of a nuclear matrix-associated domain.
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PMID:Ataxin-1 with an expanded glutamine tract alters nuclear matrix-associated structures. 935 20


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