Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0016719 (Friedreich's ataxia)
 2,098 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fibroblasts from forearm skin biopsy specimens from 3 patients with Friedreich's ataxia and controls without evidence of hypersensitivity to ionising radiation were exposed to a range of doses of gamma or x-rays up to 550 rad, and cell survival was measured by counting clones derived from single fibroblasts. Cells from two of the three Friedreich cases were found to have an abnormally low survival at the dose levels used, the difference from controls run in parallel being significant. These findings suggest the possibility of defective DNA repair processes in at least some patients with Friedreich's ataxia.
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PMID:Increased radiosensitivity of skin fibroblasts in Friedreich's ataxia. 693 42

Skin fibroblasts from seven patients with Friedreich's ataxia showed a small but significant increase in sensitivity to ionising radiation, as measured by post-irradiation clonal growth, when compared with cells from ten age-matched control subjects and from eight patients with motor neuron disease. Fibroblasts from three patients with Friedreich's ataxia also showed impairment of their ability to repair potentially lethal damage after ionising radiation. These findings are consistent with the view that defective DNA reparative mechanisms may be involved in the pathogenesis of Friedreich's ataxia.
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PMID:Studies of cellular hypersensitivity to ionising radiation in Friedreich's ataxia. 716 8

By analysis of crossovers in key recombinant families and by homozygosity analysis of inbred families, the Friedreich ataxia (FRDA) locus was localized in a 300-kb interval between the X104 gene and the microsatellite marker FR8 (D9S888). By homology searches of the sequence databases, we identified X104 as the human tight junction protein ZO-2 gene. We generated a large-scale physical map of the FRDA region by pulsed-field gel electrophoresis analysis of genomic DNA and of three YAC clones derived from different libraries, and we constructed an uninterrupted cosmid contig spanning the FRDA locus. The cAMP-dependent protein kinase gamma-catalytic subunit gene was identified within the critical FRDA interval, but it was excluded as candidate because of its biological properties and because of lack of mutations in FRDA patients. Six new polymorphic markers were isolated between FR2 (D9S886) and FR8 (D9S888), which were used for homozygosity analysis in a family in which parents of an affected child are distantly related. An ancient recombination involving the centromeric FRDA flanking markers had been previously demonstrated in this family. Homozygosity analysis indicated that the FRDA gene is localized in the telomeric 150 kb of the FR2-FR8 interval.
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PMID:The Friedreich ataxia critical region spans a 150-kb interval on chromosome 9q13. 748 55

Friedreich ataxia is a severe neurodegenerative autosomal recessive disorder of unknown biochemical defect. The Friedreich ataxia locus (FRDA) is tightly linked to the centromeric side of the D9S5 locus. We have used 'exon-trapping' to identify two new genes, approximately 100 and 200 kb centromeric to D9S5, respectively. One gene appears ubiquitously expressed while the other is prominently expressed in muscle. The ubiquitous transcript codes for a protein containing a 20 aa repeat reminiscent of simple repeats found in several ribonucleoproteins. Using the single-strand conformation polymorphism (SSCP) procedure, we searched for mutations in affected patients in the coding sequence of the two genes, as well as in a gene that we had previously identified in the same region. Eight polymorphic DNA changes but no causative mutations were found, suggesting that the genes are not candidates for Friedreich ataxia. The discovery of a simple sequence repeat polymorphism in the most centromeric gene allowed the localization within that gene of the breakpoint of a previously described recombination in a Friedreich ataxia family, therefore excluding the two distal genes from the FRDA region. The lack of causative mutations in the three genes and the position of the recombination further delineate the FRDA locus to a 300 kb interval.
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PMID:The Friedreich ataxia region: characterization of two novel genes and reduction of the critical region to 300 kb. 795 Dec 35

The hereditary ataxias are a very heterogeneous group of disorders characterized by cerebellar dysfunction that can be either isolated or accompanied by other neurological manifestations. The classification of the hereditary ataxias based on clinical or histopathological findings has been difficult because of the significant overlap of phenotypes among the various genotypes. The patterns of inheritance observed in ataxias include autosomal dominant, autosomal recessive and X-linked. Friedreich's ataxia, the most frequent form among the recessive ataxias, has been mapped to the long arm of chromosome 9 based on close linkage to the markers D9S5 and D9S15. This close linkage allows the use of these two DNA markers for prenatal diagnosis in families with one affected offspring. In the past year, significant research progress has been accomplished by applying molecular genetic studies to the dominantly inherited spinocerebellar ataxias. Spinocerebellar ataxia type 1 (SCA1), which maps to the short arm of chromosome 6, has been found to be caused by expansion of an unstable trinucleotide (CAG) repeat. This mutational mechanism explains the presence of the clinical phenomenon of anticipation in some families with SCA1. The finding of an unstable repeat in SCA1 will facilitate the diagnosis of SCA1 in familial and isolated cases and will allow preclinical and prenatal diagnosis in families with this disease. In addition to the cloning of the SCA1 gene, two dominantly inherited ataxias have been genetically mapped: SCA2, to the long arm of chromosome 12, and Machado-Joseph disease (MJD), to the long arm of chromosome 14. Given that anticipation has been observed in patients with SCA2 and MJD, it is likely that trinucleotide repeat expansion could be a common mechanism involved in all the spinocerebellar ataxias. Last, significant research progress has been accomplished in the field of hereditary ataxias associated with DNA repair defects which should facilitate our understanding of mechanisms involved in cerebellar degeneration.
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PMID:Molecular genetics of hereditary ataxias. 795 48

The Friedreich ataxia (FRDA) locus is localized on chromosome 9q13 in an interval less than 1 Mb between markers D9S202/FR1 and FR5. We cloned the FRDA candidate region in YACs, and we started a systematic search for transcripts in this region using the cDNA selection approach. Several overlapping cDNA clones mapping near the telomeric end of the FRDA minimum genetic region were isolated. Zoo blot analysis demonstrated that these cDNAs are well conserved among different species. A transcript of 4.8 kb was identified by hybridization to a Northern blot containing human brain poly(A)+ RNA. Partial sequence of these clones showed 100% homology with a previously described anonymous brain cDNA (EST01251). A search for mutations of this gene in FRDA patients and carriers is in progress. No mutations have been found to date, but we have identified a DNA polymorphism. This polymorphism was nonrecombinant with the disease in a previously described FRDA pedigree in which a recombination had occurred with more telomeric markers.
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PMID:Isolation of a new gene in the Friedreich ataxia candidate region on human chromosome 9 by cDNA direct selection. 799 57

Linkage studies with DNA polymorphic markers allowed to map the loci of three inherited ataxia and to explore genetic heterogeneity in inherited ataxia in general. The locus of Friedreich ataxia, the most frequent of all recessive ataxias, has been mapped in 9q13-q21. In addition, Friedreich ataxia is an homogeneous genetic entity since all families from all populations tested (mainly European, North-American and from the Mediterranean basin) show linkage with this locus. But the severity of the disease varied in a few families. A form of recessive ataxia associated with a selective and severe serum vitamin E deficiency, which frequently presents clinically like typical Friedreich ataxia, is not linked to 9q13-q21 markers. The autosomal recessive spastic ataxia from Charlevoix-Saguenay (a region of Quebec) is also not linked to these markers. Both entities are therefore distinct genetically from Friedreich ataxia. Among dominant ataxias, the most important group is olivo-ponto-cerebellar ataxia which is heterogeneous and for which any classification is hindered by important intra-familial variability. This group corresponds to at least three distinct loci, two of which have been mapped, one in 6p23-p24, and the other, more recently, on chromosome 12. Prenatal and presymptomatic diagnosis based on linked markers can be made for the three mapped ataxias, but only in families with an affected individual for whom the diagnosis has been ascertained by through clinical investigation or by linkage analysis if the family is large enough (mainly for the dominant diseases). Linked markers are also the first tools for the search of the defective genes by positional cloning.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Molecular genetics and familial ataxia]. 809 Oct 82

Friedreich ataxia (FRDA) is a recessive neurodegenerative disorder affecting both central and peripheral nervous systems. The mutation was mapped to chromosome 9 by its tight linkage to the polymorphic loci D9S5 and D9S15. Using informative DNA markers the allele frequencies at these loci, in up to 84 unrelated healthy persons and in 16 FRDA patients of German origin, were determined. The comparison to data from other European populations did not reveal remarkable differences. No significant linkage disequilibrium could be observed between FRDA and the loci D9S5 and D9S15 in German families.
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PMID:Allele frequencies of DNA markers genetically linked to Friedreich ataxia in the German population. 810 37

We used a modified colony survival assay to measure the sensitivity to ionizing radiation of more than 50 lymphoblastoid cell lines from normal individuals and from patients with ataxia-telangiectasia, Nijmegen breakage syndrome variants, and X-linked agammaglobulinemia. All of these disorders are associated with an increased frequency of cancer. Lymphoblastoid cell lines from patients with ataxia-telangiectasia complementation groups A, C, D, and E; ATFresno; Nijmegen breakage syndrome variants V1 and V2; and X-linked agammaglobulinemia showed marked radiosensitivity, whereas ataxia-telangiectasia heterozygotes were similar to controls. Friedreich's ataxia is not associated with increased cancer risk; lymphoblastoid cell lines from two such patients showed normal radiosensitivity. Taken together, these results suggest that some forms of X-ray sensitivity and cancer susceptibility share a common mechanism, such as an enzyme that is necessary both for the repair of radiation damage to DNA and for gene rearrangements during V(D)J recombination.
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PMID:Radiosensitivity of ataxia-telangiectasia, X-linked agammaglobulinemia, and related syndromes using a modified colony survival assay. 816 76

Fibroblasts obtained from patients with Friedreich's ataxia and normal control subjects were studied by immunocytochemistry for intermediate filament vimentin and also for in vitro proliferation. Trypsinized cells were seeded on coverslips and incubated for 1.5 h and 24 h. The expression of vimentin in cells was investigated by immunofluorescence microscopy. Cell proliferation was studied with BrdU antibody technique. Cells from patients with Friedreich's ataxia showed a slower outgrowth of vimentin filaments in comparison to cells from normal controls. These cells also incorporated less 5-bromo-2'-deoxyuridine (BrdU) into their DNA. The observations may be relevant to the clinical manifestations of the disease which involves many organs in addition to brain and spinal cord.
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PMID:Immunocytochemical studies on the vimentin distribution and cell proliferation of fibroblasts in patients with Friedreich's ataxia. 841 50


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