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)

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a recently recognized neurodegenerative disorder in fragile X premutation carriers with FMR1 alleles containing 55-200 CGG repeats. Previously, we developed a Drosophila model of FXTAS and demonstrated that transcribed premutation repeats alone are sufficient to cause neurodegeneration, suggesting that rCGG-repeat-binding proteins (RBPs) may be sequestered from their normal function by rCGG binding. Here, we identify Pur alpha and hnRNP A2/B1 as RBPs. We show that Pur alpha and rCGG repeats interact in a sequence-specific fashion that is conserved between mammals and Drosophila. Overexpression of Pur alpha in Drosophila could suppress rCGG-mediated neurodegeneration in a dose-dependent manner. Furthermore, Pur alpha is also present in the inclusions of FXTAS patient brains. These findings support the disease mechanism of FXTAS of rCGG repeat sequestration of specific RBPs, leading to neuronal cell death, and implicate that Pur alpha plays an important role in the pathogenesis of FXTAS.
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PMID:Pur alpha binds to rCGG repeats and modulates repeat-mediated neurodegeneration in a Drosophila model of fragile X tremor/ataxia syndrome. 1769 5

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a recently described neurodegenerative disorder of older adult carriers of premutation alleles (60-200 CGG repeats) in the fragile X mental retardation gene (FMR1). It has been proposed that FXTAS is an RNA-mediated neurodegenerative disease caused by the titration of RNA-binding proteins by the CGG repeats. To test this hypothesis, we utilize a transgenic Drosophila model of FXTAS that expresses a premutation-length repeat (90 CGG repeats) from the 5' UTR of the human FMR1 gene and displays neuronal degeneration. Here, we show that overexpression of RNA-binding proteins hnRNP A2/B1 and CUGBP1 suppresses the phenotype of the CGG transgenic fly. Furthermore, we show that hnRNP A2/B1 directly interacts with riboCGG repeats and that the CUGBP1 protein interacts with the riboCGG repeats via hnRNP A2/B1.
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PMID:RNA-binding proteins hnRNP A2/B1 and CUGBP1 suppress fragile X CGG premutation repeat-induced neurodegeneration in a Drosophila model of FXTAS. 1769 5

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a newly described disorder characterized by progressive action tremor and ataxia that occurs in premutation carriers of the FMR1 gene. The incidence of FMR1 premutated carriers in the general population is relatively high, and therefore FXTAS might explain a considerable number of sporadic, late-onset ataxias. To better establish the prevalence of FXTAS among undiagnosed Spanish patients with ataxia, we have performed a FMR1 premutation screening. Our results evidenced three individuals carrying premutated alleles, giving an estimated FXTAS prevalence of 1.95% among patients with late-onset ataxia (1.15% for males and 3% for females). Molecular characterization of premutation carriers evidences lower fragile X mental retardation 1 protein levels and increased FMR1 mRNA levels. Clinical and neuroimaging findings support FXTAS diagnosis in these patients. Because of the high prevalence of FMR1 premutation in the general population, the description and characterization of the FXTAS syndrome is of great interest as it may represent one of the more common monogenic causes of ataxia, tremor, and dementia. The results obtained in this study demonstrate that FXTAS should be incorporated to spinocerebellar ataxia genetic screening protocols. Early diagnosis of these patients benefits not only them but also the rest of the family that should be advised for the fragile X syndrome.
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PMID:FXTAS in spanish patients with ataxia: support for female FMR1 premutation screening. 1791 21

The CGG triplet repeat found within the 5'UTR of the FMR1 gene is involved in the pathogenesis of both fragile X syndrome and fragile X-associated tremor/ataxia syndrome (FXTAS). The repeat has been shown to form both hairpins and tetraplexes in DNA; however, the secondary structure of CGG-repeat RNA has not been well defined. To this end, we have performed NMR spectroscopy on in vitro transcribed CGG-repeat RNAs and see clear evidence of intramolecular hairpins, with no evidence of tetraplex structures. Both C*G and G*G base pairs form in the hairpin stem, though in a dynamic equilibrium of conformations. In addition, we investigated the effect of an AGG repeat interruption on hairpin stability; such interruptions are often interspersed within the CGG repeat element and are thought to modulate secondary structure of the RNA. While the AGG repeat lowers the Tm of the hairpin at low Mg2+ concentrations, this difference disappears at physiological Mg2+ levels.
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PMID:Secondary structure and dynamics of the r(CGG) repeat in the mRNA of the fragile X mental retardation 1 (FMR1) gene. 1796 27

Fragile X-associated tremor/ataxia (FXTAS) is a late onset disorder caused by a premutation in the FMR1 gene, in which neurological symptoms are associated with white matter (wm) changes, especially within the middle cerebellar peduncles (MCP sign), seen on magnetic resonance images (MRIs). We report a discrepancy between obvious radiological presentations and minimal clinical involvement in two younger male premutation carriers. These carriers, aged 52 and 39 years, showed distinct MCP sign, but reported no neurological symptoms. If this discrepancy represents the initial stage of FXTAS, our findings suggest the possibility of early diagnosis from MRI scans.
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PMID:A low symptomatic form of neurodegeneration in younger carriers of the FMR1 premutation, manifesting typical radiological changes. 1805 83

Fragile X syndrome, which is caused by expansion of a (CGG)(n) repeat in the FMR1 gene, occurs in approximately 1:3500 males and causes mental retardation/behavioral problems. Smaller (CGG)(n) repeat expansions in FMR1, premutations, are associated with premature ovarian failure and fragile X-associated tremor/ataxia syndrome. An FMR1-sizing assay is technically challenging because of high GC content of the (CGG)(n) repeat, the size limitations of conventional PCR, and a lack of reference materials available for test development/validation and routine quality control. The Centers for Disease Control and Prevention and the Association for Molecular Pathology, together with the genetic testing community, have addressed the need for characterized fragile X mutation reference materials by developing characterized DNA samples from 16 cell lines with repeat lengths representing important phenotypic classes and diagnostic cutoffs. The alleles in these materials were characterized by consensus analysis in nine clinical laboratories. The information generated from this study is available on the Centers for Disease Control and Prevention and Coriell Cell Repositories websites. DNA purified from these cell lines is available to the genetics community through the Coriell Cell Repositories. The public availability of these reference materials should help support accurate clinical fragile X syndrome testing.
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PMID:Consensus characterization of 16 FMR1 reference materials: a consortium study. 1816 76

Fragile X Syndrome is the most common heritable form of mental retardation caused by silencing of the FMR1 gene, which arises from intergenerational trinucleotide repeat expansion leading to full mutation. An intermediary carrier condition, known as the premutation, is characterized by expansion up to 200 repeats without concomitant gene silencing. This prevalent allelic variant was initially thought to be free of phenotypic effects. However, recent reports have identified a degenerative disease, Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) in older men as well as premature ovarian failure in women. Previously reports are inconsistent regarding the neuropsychiatric phenotype associated with premutation due to small sample sizes, ascertainment bias, lack of adequate control groups, administration of measures with poor psychometric properties, and the confounding effects of FXTAS. We addressed these problems by conducting a controlled study of male carriers (n = 40) of the premutation without manifest symptoms of FXTAS, comparing their responses on specific, reliable, and valid measures of neuropsychiatric functioning to those of individuals with shared family environment (n = 22) and non-carrier comparison males (n = 43). Multivariate analyses revealed that the premutation confers significant risk for working memory difficulties, an associated feature of Attention-Deficit Disorder. Furthermore, both the family controls and men with premutation exhibited higher rates of Alcohol Abuse as compared to non-carrier control men. These findings highlight the importance of recognizing the distinct phenotypic outcomes that characterize the Fragile X premutation and the subtle risk factors that can act as precursors to more significant psychiatric impairment.
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PMID:Impact of the Fragile X mental retardation 1 (FMR1) gene premutation on neuropsychiatric functioning in adult males without fragile X-associated Tremor/Ataxia syndrome: a controlled study. 1816 71

While an established protocol exists for diagnosing individuals with the fragile X-associated tremor/ataxia syndrome (FXTAS), a quantitative measure of tremor and ataxia is needed. Using the CATSYS system to quantify movement abnormalities, we were able to record tremor, postural sway, manual (hand and finger) coordination, and reaction time in males with the FMR1 premutation, both with and without FXTAS, and compare them to controls. We evaluated 16 males diagnosed with FXTAS, 16 males with the premutation without FXTAS (non-FXTAS), and 14 age-matched controls. The CATSYS system detected, in the dominant hand, a difference in intention tremor between the FXTAS group and controls (P = 0.0008). The 30-sec postural sway tasks revealed differences between the FXTAS group and controls, both with eyes open and closed (P = 0.0004 and P = 0.0031, respectively). There was also a difference between FXTAS and non-FXTAS 30-sec postural sway performances with eyes open (P = 0.0008). The 10-sec postural sway tasks (with eyes closed) served to confirm the differences between the FXTAS group and both the controls (P = 0.0017) and non-FXTAS premutation carriers (P = 0.0016). These results demonstrate that the quantitative measures of the CATSYS system can document significant differences in intention tremor and postural sway in patients with FXTAS compared to controls.
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PMID:A quantitative assessment of tremor and ataxia in FMR1 premutation carriers using CATSYS. 1824 Oct 72

A late onset neurological syndrome in carriers of premutation in FMR1 gene was recently described. The condition was named fragile-X-associated tremor/ataxia syndrome (FXTAS) and includes intentional tremor, cerebellar ataxia, parkinsonism, and cognitive deficit. We ascertained the contribution of FMR1 premutation to the phenotypes ataxia, tremor and/or parkinsonism. Sixty-six men over 45 years old presenting these symptoms, isolated or combined, were tested. Also, 74 normal men, randomly chosen in the population, formed the control group. In the patient group, no premutation carrier was found, which is in agreement with other observed frequencies reported elsewhere (0-5% variation). No significant differences were found when comparing gray zone allele frequencies among target and control groups. The FXTAS contribution in patients with phenotypic manifestations of FXTAS was 15/748 (2%). The presence of gray zone alleles is not correlated with FXTAS occurrence.
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PMID:Frequency of FMR1 premutation in individuals with ataxia and/or tremor and/or parkinsonism. 1827 22

To determine the prevalence of Fragile X-associated Tremor Ataxia Syndrome (FXTAS) among men with undiagnosed ataxic disorders. PCR amplification of CGG repeats in the FMR1 gene and a chart review of clinical features were performed for 286 male subjects who had non diagnostic genetic testing for spinocerebellar ataxia between November 1998 and October 2002 prior to widespread clinical testing of FXTAS. Chart review showed that 55% of tested subjects manifested only one cardinal clinical feature of FXTAS (progressive intention tremor, ataxia, and cognitive decline), 20% had two of the three findings, and 4% had all three. Gait ataxia associated with clinical features not characteristic of FXTAS was reported in 47% of subjects. Molecular analysis yielded one FMR1 premutation (100 CGG repeats). Combining our data with that of comparable published studies shows 17/1,320 (1.3%) males tested for adult-onset ataxia had FMR1 premutations. FMR1 premutations are an uncommon cause of spinocerebellar ataxia. This study is in agreement with other similar studies and supports recommendations that testing be considered only if there are additional supporting clinical features indicating that a possible FMR1 premutation may be involved.
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PMID:Premutations in the FMR1 gene are uncommon in men undergoing genetic testing for spinocerebellar ataxia. 1836 64


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