Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 6 (SCA6) is a common cause of dominantly inherited ataxia due to an expansion of the CAG repeat in the CACNA1A gene. Affected individuals from the same population share a common haplotype, raising the possibility that most SCA6 cases have descended from a small number of common founders across the globe. To test this hypothesis, we carried out haplotype analysis on SCA6 families from Europe, South America and the Far East, including an established de novo SCA6 expansion. A core CACNA1A disease haplotype was found in affected individuals across the globe. This was also present in the unaffected father of the de novo case, suggesting that the shared chromosome predisposes to the CAG repeat expansion at the SCA6 locus. The SCA6 expansion lies within a CpG island, which could act as a cis-acting element predisposing to repeat expansion as for other CAG/CTG repeat diseases. Polymorphic variation in this region may explain the high-risk haplotype found in SCA6 families.
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PMID:Pathogenic expansions of the SCA6 locus are associated with a common CACNA1A haplotype across the globe: founder effect or predisposing chromosome? 1828 29

Spinocerebellar ataxia type 2 typically presents in adulthood with progressive ataxia, dysarthria, tremor, and slow saccadic eye movements. Childhood-onset spinocerebellar ataxia type 2 is rare, and only the infantile-onset form has been well characterized clinically. This article describes a girl who met all developmental milestones until age 3(1/2) years, when she experienced cognitive regression that preceded motor regression by 6 months. A diagnosis of spinocerebellar ataxia type 2 was delayed until she presented to the emergency department at age 7 years. This report documents the results of her neuropsychologic evaluation at both time points. This case broadens the spectrum of spinocerebellar ataxia type 2 presentation in childhood, highlights the importance of considering a spinocerebellar ataxia in a child who presents with cognitive regression only, and extends currently available clinical information to help clinicians discuss the prognosis in childhood spinocerebellar ataxia type 2.
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PMID:Spinocerebellar ataxia type 2 presenting with cognitive regression in childhood. 1834 58

Spinocerebellar ataxia type 10 (SCA10) is a dominantly inherited neurodegenerative disease caused by expansion of the ATTCT pentanucleotide repeat in intron 9 of a novel gene, ATXN10, on chromosome 22q13.3. It is clinically characterized by progressive ataxia, seizures, and anticipation, which can vary within and between families. The length of the expanded ATTCT repeats is highly unstable on paternal transmission and shows a variable degree of somatic and germline instabilty, revealing complex SCA10 genetic mechanisms. Moreover, the purity of the expanded repeat element may be a disease modifier. ATTCT repeats have been recently shown to form unpaired DNA structure and may serve as an aberrant DNA replication origin, potentially contributing to repeat instability and cell death. How this untranslated ATTCT expansion leads to neurodegeneration has been still controversial. We discuss several possible pathogenic mechanisms for SCA10, and growing number of evidence indicates a gain-of-function RNA mechanism, similar to the myotonic dystrophies caused by non-coding CTG or CCTG repeat expansions.
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PMID:[Molecular and genetic analysis of spinocerebellar ataxia type 10 (SCA10)]. 1838 26

Spinocerebellar ataxia 21 is a slowly progressive and mild ataxia associated with extrapyramidal signs. Affected subjects exhibit a moderate gait and limb ataxia variably associated with akinesia, tremor, rigidity, hyporeflexia, and mild cognitive impairment. The responsible gene has been assigned to a 19 Mbases interval on chromosome 7p in a single French family. No evidence of significant linkage to this locus was found in 21 other families obtained from the EUROSCA consortium. The locus interval contains several candidate genes that could be responsible for the disease. Direct sequencing of NDUFA4, PHF14, KIAA0960, ARLA4, ETV1, DGKB, HDAC9, FERD3L, ITGB8, and SP4 genes were performed, but all the direct mutation analyses were negative excluding pathogenic mutations associated with the disease. Therefore, the gene responsible for SCA21 remains to be identified.
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PMID:Slowly progressive spinocerebellar ataxia with extrapyramidal signs and mild cognitive impairment (SCA21). 1841 88

Spinocerebellar ataxia type 8 (SCA8) is a dominantly inherited, slowly progressive neurodegenerative disorder caused by a CTG.CAG repeat expansion located on chromosome 13q21. The expansion mutation was isolated directly from the DNA of a single patient using RAPID cloning and subsequently shown to co-segregate with disease in additional ataxia families including a seven-generation kindred (the MN-A family). The size-dependent penetrance of the repeat found in the large MN-A kindred makes it appear as though some parts of the family have a dominant disorder while other parts of this same family have recessive or sporadic forms of ataxia. While the linkage and size-dependent penetrance of the SCA8 CTG.CAG expansion in the MN-A family argue that the SCA8 expansion causes ataxia, the reduced penetrance in other SCA8 families and the discovery of expansions in the general population have led to a controversy surrounding whether or not the SCA8 expansion is pathogenic. A recently reported mouse model in which SCA8 BAC-expansion but not BAC-control lines develop a progressive neurological phenotype now demonstrates the pathogenicity of the (CTG.CAG)(n) expansion. These mice show a loss of cerebellar GABAergic inhibition and, similar to human patients, have 1C2-positive intranuclear inclusions in Purkinje cells and other neurons. Additional studies demonstrate that the SCA8 expansion is expressed in both directions (CUG and CAG) and that a novel gene expressed in the CAG direction encodes a pure polyglutamine expansion protein (ataxin 8, ATXN8). Moreover, the expression of non-coding (CUG)(n) expansion transcripts (ataxin 8 opposite strand, ATXN8OS) and the discovery of intranuclear polyglutamine inclusions suggest SCA8 pathogenesis may involve toxic gain-of-function mechanisms at both the protein and RNA levels. Our data, combined with the recently reported antisense transcripts spanning the DM1 repeat expansion in the CAG direction and the growing number of reports of antisense transcripts expressed throughout the mammalian genome, raises the possibility that bidirectional expression across pathogenic microsatellite expansions may occur in other expansion disorders, and that potential pathogenic effects of mutations expressed from both strands should be considered.
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PMID:Bidirectional expression of the SCA8 expansion mutation: one mutation, two genes. 1841 92

Spinocerebellar ataxia type 1 (SCA1) is an autosomal-dominant neurodegenerative disorder characterized by ataxia and progressive motor deterioration. SCA1 is caused by expansion of the polyglutamine tract in the SCA1 gene product, ataxin-1. We previously reported that the E2 ubiquitin-conjugating enzyme UbcH6 interacts with and ubiquitinates the ataxin-1 proteins as an E2-substrate cognate pair in the ubiquitin-proteasome system. In the present study, we further investigated whether the function of ataxin-1 is associated with UbcH6 and found that UbcH6 regulates the transcriptional repression activity of ataxin-1. The overexpression of UbcH6 reduced the transcriptional repression activity of ataxin-1. Interestingly, ataxin-1(30Q) was more affected by the presence of UbcH6 than ataxin-1(82Q), implying that the length of the polyglutamine tract in ataxin-1 might be involved in determining the stability of ataxin-1. The half-life of ataxin-1(82Q) was longer than that of ataxin-1(30Q) in the presence of UbcH6. shRNAs targeting UbcH6 enhanced the transcriptional repression activity of ataxin-1. In addition, the overexpression of UbcH6 reduced the formation of ataxin-1 aggregates. Our studies demonstrate that UbcH6 modulates the transcriptional repression activity of ataxin-1 by modulating the degradation of ataxin-1, suggesting that UbcH6 may have some therapeutic potential in the treatment of SCA1.
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PMID:The ubiquitin-conjugating enzyme UbcH6 regulates the transcriptional repression activity of the SCA1 gene product ataxin-1. 1851 31

An increasing number of inherited neurodegenerative diseases are known to be caused by the expansion of unstable trinucleotide repeat tracts. Spinocerebellar ataxia type 8 (SCA8) has been identified as being partly caused by a CTG expansion in an untranslated, endogenous antisense RNA that overlaps the Kelch-like 1 (KLHL1) gene. Clinically, SCA8 patients show similar features to those with the other SCAs, including limb and truncal ataxia, ataxic dysarthria and horizontal nystagmus, all of which are signs of dysfunction of the cerebellar system. However, allele sizes within the SCA8 proposed pathogenic range have been reported in patients with ataxia of unknown etiology, in individuals from pedigrees with other SCA or Friedreich's ataxia, and in patients with Alzheimer's disease, schizophrenia or parkinsonism. These observations suggest that mutation of the SCA8 locus might affect neurons other than the cerebellum. Antisense transcripts are known to regulate complementary sense transcripts and are involved in several biologic functions, such as development, adaptive response, and viral infection. In order to test whether SCA8 affects the KLHL1 expression by antisense RNA in brain cells, we examined the expression pattern of KLHL1 and SCA8 in human tissues and in mouse brain regions. SCA8 expression was colocalized with KLHL1 transcript in many brain regions whose functions are correlated to the clinical symptoms of SCA8 patients. These findings lead to the hypothesis of a possible relevance that SCA8 transcript downregulates KLHL1 expression through an antisense mechanism, which then leads to SCA8 neuropathogenesis.
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PMID:SCA8 mRNA expression suggests an antisense regulation of KLHL1 and correlates to SCA8 pathology. 1870 37

The CACNA1A gene codes for the alpha(1A) pore-forming subunit of Ca(2+) voltage-gated Cav2.1 channels. CACNA1A mutations are responsible for Familial Hemiplegic Migraine (FHM) type 1, Episodic Ataxia (EA) type 2 and Spinocerebellar Ataxia type 6. The structure of the human gene includes, at present, 49 exons; however almost nothing is known about the 5' regulatory region, and there is now evidence suggesting the presence of additional exons at the 3' of the gene. The 892 bp fragment upstream of exon 1 and its deletion mutants were characterised for their transcriptional activity by using luciferase as a reporter gene. The 3' region was analysed by Rapid Amplification of the cDNA 3' End. Both regions were screened for mutations in a series of FHM and EA patients by SSCP and sequencing. At the 5' end of the gene a minimal promoter region was identified within the first 497 bp from ATG. By screening a larger fragment for mutations, the 5 bp deletion (g.-757_-753delCTTTC) was identified in a FHM patient. The deletion significantly increased the transcriptional activity, most likely due to the removal of half a turn of the DNA helix, changing the orientation of downstream binding sites for transcriptional factors. At the 3' end of the gene a new exon 48, followed by a strong poly-A signal, was identified as well as a new splice variant. The 5 bp insertion (g.38429_38430insCTTTT) in this exon was found in an EA patient. The two new regions can open the way for the study of human CACNA1A gene expression regulation and can be sites of mutations associated with FHM or EA phenotypes.
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PMID:Newly characterised 5' and 3' regions of CACNA1A gene harbour mutations associated with Familial Hemiplegic Migraine and Episodic Ataxia. 1897 83

Spinocerebellar ataxia type 10 (SCA10) is a dominantly inherited neurodegenerative disease caused by expansion of the ATTCT pentanucleotide repeat in intron 9 of a novel gene, ATXN10, on chromosome 22q13.3. It is clinically characterized by progressive ataxia, seizures, and anticipation, which can vary within and between families. The length of the expanded ATTCT repeats is highly unstable on paternal transmission and shows a variable degree of somatic and germline instabilty, revealing complex SCA10 genetic mechanisms. How this untranslated ATTCT expansion leads to neurodegeneration has been still controversial. Growing number of evidence indicates a gain-of-function RNA mechanism, similar to the myotonic dystrophies caused by non-coding CTG or CCTG repeat expansions.
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PMID:[Molecular and genetic analysis of spinocerebellar ataxia type 10 (SCA10)]. 1919 92

Spinocerebellar ataxia type 6 (SCA6) is a calcium channelopathy due to a pathological CAG repeat expansion in CACNL1A4. Patients frequently describe paroxysmal vertigo early in the disease course, but it is not clear whether this is central or labyrinthine in origin. To address this issue we studied 21 SCA6 patients. Symptoms of vertigo were defined using a structured questionnaire. Signs were recorded during a standardised bed-side vestibular examination that included systematic positional testing with Frenzel goggles.Brief, recurrent attacks of vertigo occurred in 13 patients, usually preceding the onset of ataxia. Nystagmus was observed behind Frenzel goggles in 14 patients, and was induced either during positional testing, or head shaking in 20 patients. Only one patient had findings typical of benign paroxysmal positional vertigo (BPPV). Combined downbeat and horizontal gaze-evoked nystagmus ("side-pocket") was the most common form, occurring most commonly in supine and head-hanging positions, and following horizontal head-shaking. Nystagmus beating away from the ground (apogeotropic) occurred in 9 patients as they lay on their side.In conclusion, vertigo and abnormalities on bedside vestibular examination are common in SCA6, with forms of nystagmus typical of cerebellar, rather than labyrinthine, disease. These findings demonstrate phenotypic overlap between SCA6 and episodic ataxia type 2, which are both due to mutations in CACNL1A4.
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PMID:Vertigo and vestibular abnormalities in spinocerebellar ataxia type 6. 1922 13


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