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)

Several human disorders are now known to be caused by expansion of unstable trinucleotide repeat sequences, including fragile X syndrome (FRAX), myotonic dystrophy (DM), spinal and bulbar muscular atrophy (SBMA, also known as Kennedy disease), Huntington disease (HD), dentatorubral-pallidoluysian atrophy (DRPLA), spinocerebellar ataxia type 1 (SCA1), Machado-Joseph disease (MJD), and Friedreich ataxia. As these diseases are studied in more detail, important differences have emerged in the nature of the unstable repeats and the mechanism by which the repeat expansions cause disease symptoms. There are already animal models of some of these disorders, and these are important resources for studying pathology and therapeutic strategies. Diagnostic procedures for these disorders are only beginning to be standardized, and effective therapy will have to wait for further information on disease mechanisms. Much has been learned since discovery of the fragile X syndrome gene in 1991, but much remains to be done.
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PMID:Trinucleotide repeat disorders in humans: discussions of mechanisms and medical issues. 900 50

Expansion of trinucleotide repeats has been identified as a common mechanism of hereditary neurodegenerative diseases including spinal and bulbar muscular atrophy (SBMA), Huntington's disease, dentatorubral-pallidoluysian atrophy (DRPLA), Machado-Joseph disease (MJD), fragile X syndrome, myotonic dystrophy and Friedreich's ataxia. These diseases share unique features, which are difficult to explain based on Mendelian inheritance. These unique clinical genetic features include genetic anticipation and a broad spectrum of clinical presentations, which have been shown to be associated with the instability of the trinucleotide repeats. Recent studies suggest that gene products with expanded polyglutamine tracts may be toxic to neuronal cells, and the mechanisms of neurotoxicity should be thoroughly investigated. To develop therapeutic measures, creation of animal models or cell culture systems for the investigation of neurotoxicity will be indispensable.
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PMID:Molecular genetics of triplet repeats: unstable expansion of triplet repeats as a new mechanism for neurodegenerative diseases. 905 92

The human genome has many nucleotide repeat sequences. These range from a single repeating base to entire duplicated genes. Expansion of repeating triplets of nucleotides in the genome has recently been associated with nine degenerative and developmental neuropsychiatric diseases: fragile X syndrome, fragile X-linked mental retardation, myotonic dystrophy, Friedreich's ataxia, spinal and bulbar muscular atrophy, Huntington's disease, spinocerebellar ataxia type 1, dentatorubral-pallidoluysian atrophy, and Machado-Joseph disease. These diseases are all conditions of the central nervous system; in all of them, the inheritance pattern usually exhibits the phenomenon of anticipation (defined as progressively earlier age of onset or a worsening disease severity over successive generations), and the severity of the phenotypic expression and penetrance appears to be related to the extent of the triplet expansion. Identification of this pathological genetic phenomenon solves several of the mysteries that surrounded these conditions but raises many important questions regarding pathogenic mechanisms that may be shared. There is some indication that triplet expansions may also underlie other neuropsychiatric conditions such as schizophrenia or bipolar disorder.
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PMID:Triplet repeat gene sequences in neuropsychiatric diseases. 938 23

The discovery of unstable DNA sequences as the cause of genetic disease is a fascinating new area in human genetics, raising a number of important questions addressing the understanding of both the mechanisms and the effects of this new type of mutation. Trinucleotide repeat expansion mutations have been identified in a number of neurodegenerative diseases, including spinal and bulbar muscular atrophy (SBMA), fragile X syndrome (FRAXA and FRAXE), myotonic dystrophy (DM), Huntington's disease (HD), spinocerebellar ataxia types 1, 2, 3, 6, 7 (SCA1, SCA2, SCA3, SCA6, SCA7), dentatorubral-pallidoluysian atrophy (DRPLA), Friedreich's ataxia (FRDA) and autosomal dominant pure spastic paraplegia (ADPSP). They have been traced to genetic variation in the length of (CTG)n/(CAG)n, (CGG)n/(CCG)n, or (GAA)n/(TTC)n triplet repeats in DNA. In normal individuals these loci contain a short length of triplet repeats (usually 5-40), which is polymorphic within the population. Increases in the lengths of the translated triplet repeats to 40-100 are associated with disease symptoms, whereas the untranslated triplet repeats to 200-3000 are associated with the disease. We concentrated on repeat expansions in myotonic dystrophy. In this symposium, we outline the molecular aspects of myotonic dystrophy including DNA diagnosis and anticipation, and review the similarities and differences among these triplet repeat diseases.
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PMID:[Genomic instability and neurodegenerative disease]. 1006 64

Approximately 44% of cases of spinocerebellar ataxia (SCA) in Hokkaido, the northernmost island of Japan, were estimated to be inherited. To determine the prevalence of triplet repeat expansion in hereditary SCA patients, we genotyped seven genetically defined dominant SCAs in 349 patients, including 266 patients from 77 families, 78 probands from unrelated families with hereditary late-onset SCA, and five patients in whom a family history of SCA was not demonstrated. The frequency of each disorder in a total of 155 unrelated families was 23.9% for Machado-Joseph disease (MJD), 29.0% for SCA6, 9.7% for SCA1, 7.7% for SCA2, and 2.6% for dentatorubral-pallidoluysian atrophy. Abnormal expansion of triplet repeats for SCA7 and SCA8 was not detected. A total of 27.1% of the patients had still unknown SCA mutations. In addition, the GAA repeat in the frataxin gene was not abnormally expanded in 13 early-onset SCA patients with clinical features similar to those of Friedreich ataxia. Comparison of our results with those from other centers handling SCA showed that MJD is prevalent throughout Japan, but the frequencies of other dominant SCAs differ considerably even within Japan.
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PMID:Prevalence of triplet repeat expansion in ataxia patients from Hokkaido, the northernmost island of Japan. 1078 56

We investigated the genotype frequencies of patients with spinocerebellar ataxias (SCA), using a community-based prevalence study among 613,349 inhabitants in Tottori prefecture, Japan. Prevalence date was April 1, 1998. On this date, 109 SCA patients were identified in this community. The prevalence of SCA was 17.8 per 100,000 individuals. The most common cause of inherited SCA was a mutation at the SCA6 locus (25%), followed by mutation at the SCA1 locus (15%), SCA3 locus (5%) and dentatorubral-pallidoluysian atrophy locus (5%). None of the expanded alleles was found in SCA2, SCA7 or Friedreich's ataxia. Mutation at SCA6 was also the most common form of sporadic SCA at 11%. Prevalences per 100,000 individuals were as follows: SCA6, 2.40; SCA1, 0.48; DRPLA, 0.32, and SCA3, 0.16.
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PMID:A genetic epidemiological study of spinocerebellar ataxias in Tottori prefecture, Japan. 1135 84

Huntington's disease (HD) classically presents with movement disorder, cognitive dysfunction and behavioral problems but is phenotypically variable. One percent of patients with HD-like symptoms lack the causative mutation and are considered HD phenocopies. Genetic diseases known to cause HD phenocopies include HD-like syndromes HDL1, HDL2, and HDL4 (SCA17). HD has phenotypic overlap with dentatorubral-pallidoluysian atrophy, the spinocerebellar ataxias and neuroferritinopathy. Identifying the genetic basis of HD phenocopies is important for diagnosis and may inform the search for HD genetic modifiers. We sought to identify neurogenetic diagnoses in the largest reported cohort of HD phenocopy patients. Two hundred eighty-five patients with syndromes consistent with HD, who were HD expansion-negative, were screened for mutations in PRNP, JPH3, TBP, DRPLA, SCA1, SCA2, SCA3, FTL and FRDA. Genetic diagnoses were made in 8 subjects: we identified 5 cases of HDL4, 1 of HDL1 and 1 of HDL2. One patient had Friedreich's ataxia. There were no cases of DRPLA, SCA1, SCA2, SCA3, or neuroferritinopathy. HD phenocopies are clinically and genetically diverse and a definitive genetic diagnosis is currently possible in only a minority of cases. When undertaken, it should be clinically directed and patients and clinicians should be prepared for the low probability of reaching a genetic diagnosis in this group of patients.
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PMID:Huntington's disease phenocopies are clinically and genetically heterogeneous. 1818 Dec 6

Inherited ataxias are a heterogeneous group of disorders characterized by autosomal dominant and recessive inheritance. Recent advances in genetic research have resulted in an improved comprehension of their clinical presentation. Autosomal dominant cerebellar ataxias (ADCAs) include spinocerebellar ataxias (SCAs) and dentatorubral-pallidoluysian atrophy (DRPLA); six of these have been found to be trinucleotide repeat disorders. Episodic ataxia, types 1 and 2, are at present recognized to be channelopathies, caused by point mutations. Friedreich's ataxia (FA) which is an autosomal recessive disorder, resulting from a a unique trinucleotide repeat, is now recognized to have a wide age of onset and clinical spectrum. Ataxia-telangiectasia (AT), also an autosomal recessive cerebellar ataxia, is characterized by immunodeficiency. In this article, the genetic and clinical characteristics of these diseases are reviewed in detail.
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PMID:A review of the inherited ataxias: recent advances in genetic, clinical and neuropathologic aspects. 1859 Nov 6

It has been reported that patients with spinocerebellar degenerations (SCDs) have cognitive dysfunction as well as limb and truncal ataxia, dysarthria and dysphagia. We review cognitive dysfunction in common types of SCD, including spinocerebellar ataxia types 1, 2, 3, 6, and 17, dentatorubral-pallidoluysian atrophy, Friedreich's ataxia, and multiple system atrophy. There are few studies that address cognitive function in SCD. Although there are few comparison studies among the various SCDs, cognitive dysfunction may be more common and severe in spinocerebellar ataxia type 17 and dentatorubral-pallidoluysian atrophy. While cognitive dysfunction in SCD appears to represent frontal dysfunction, the mechanisms of cognitive dysfunction have not been directly clarified. Nevertheless, various lesions, including those in the cerebrocerebellar circuitry, cortico-striatal-thalamocortical circuitry, and the frontal lobe, may influence cognitive function to various degrees for each disease.
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PMID:Cognitive impairment in spinocerebellar degeneration. 1929 12

Repeat expansion has been implicated in 10 out of 17 candidate genes identified for autosomal dominant cerebellar ataxias (ADCAs)-commonly referred as spinocerebellar ataxias (SCAs). Though genetically distinct, the SCAs share a large number of features that confound their clinical classification. In addition, there is a difference in the prevalence and phenotypic expression of ataxias between different ethnic groups. We have created a new SCA-locus-specific variation database (LSVD) that aims to catalog and integrate information on SCAs associated with trinucleotide repeat expansion (SCA1, SCA 2, SCA 3, SCA 6, SCA 7, SCA 8, SCA 12, SCA 17, Friedreich's ataxia [FRDA], and dentatorubral-pallidoluysian atrophy [DRPLA]) from all over the world. The database has been developed using the Leiden Open (source) Variation Database (LOVD) software (Leiden University Medical Center, Leiden, the Netherlands). The database houses detailed information on clinical features, such as age and symptom at onset, mode of inheritance, and genotype information, pertaining to the SCA patients from more than 400 families across India. All the compiled genotype data conforms to the HGVS Nomenclature guidelines. This would be a very useful starting point for understanding the molecular correlates of phenotypes in ataxia-a multilocus disease in which related molecular mechanisms converge to overlapping phenotypes.
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PMID:SCA-LSVD: a repeat-oriented locus-specific variation database for genotype to phenotype correlations in spinocerebellar ataxias. 1937 Jul 69


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