51
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Storey E. Dominantly inherited ataxias. Part II. J Clin Neurosci 1998; 5:369-77. [DOI: 10.1016/s0967-5868(98)90263-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/1998] [Accepted: 02/27/1998] [Indexed: 10/26/2022]
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52
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Sasaki H, Wakisaka A, Sanpei K, Takano H, Igarashi S, Ikeuchi T, Iwabuchi K, Fukazawa T, Hamada T, Yuasa T, Tsuji S, Tashiro K. Phenotype variation correlates with CAG repeat length in SCA2--a study of 28 Japanese patients. J Neurol Sci 1998; 159:202-8. [PMID: 9741408 DOI: 10.1016/s0022-510x(98)00166-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Spinocerebellar ataxia-2 (SCA2) is an autosomal dominant ataxia caused by an abnormal CAG repeat expansion in a novel gene on chromosome 12q24.1. The size of the mutant allele is unstable during transmission, and correlates inversely with age at onset. We studied eight Japanese SCA2 families, including 28 patients, to assess the effect of repeat length on the phenotype features of SCA2. Frequencies of slow eye movements (SEM), reflex activity, dementia, choreiform movements, and axial tremor correlated significantly with CAG repeat size. Parkinsonism was seen in a man homozygote for SCA2 mutation. The clinical variety of SCA2 is apparently influenced by the size of the mutant allele, as is the case in other CAG repeat disorders.
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Affiliation(s)
- H Sasaki
- Department of Neurology, Hokkaido University, School of Medicine, Sapporo, Japan.
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53
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Affiliation(s)
- M E MacDonald
- Molecular Neurogenetics Unit, Massachusetts General Hospital East, Charlestown 02129, USA
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54
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Storey E. Dominantly inherited ataxias. Part I. J Clin Neurosci 1998; 5:257-64. [DOI: 10.1016/s0967-5868(98)90059-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/1997] [Accepted: 02/08/1998] [Indexed: 11/25/2022]
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55
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Takiyama Y, Sakoe K, Namekawa M, Soutome M, Esumi E, Ogawa T, Ishikawa K, Mizusawa H, Nakano I, Nishizawa M. A Japanese family with spinocerebellar ataxia type 6 which includes three individuals homozygous for an expanded CAG repeat in the SCA6/CACNL1A4 gene. J Neurol Sci 1998; 158:141-7. [PMID: 9702684 DOI: 10.1016/s0022-510x(98)00108-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We describe a Japanese family which includes 13 patients in five generations who have dominantly inherited ataxia. Molecular testing revealed that in these patients the SCA6/CACNL1A4 gene carries the smallest known expanded CAG repeat (21 repeat units). The clinical features of these patients exhibited predominantly cerebellar ataxia with onset late in adult life and a very slowly progressive disease course. In addition, this SCA6 family showed some characteristic clinical and genetic features, including (1) apparent lack of genetic anticipation, with an intergenerationally stable CAG repeat size and (2) down-beat nystagmus and diabetes mellitus in some of the SCA6 patients. We identified three individuals homozygous for an expanded CAG repeat (21/21) in the SCA6/CACNL1A4 gene, two of whom were symptomatic. There were no apparent differences in clinical phenotype between the individuals homozygous and those heterozygous for an expanded CAG repeat in the SCA6/CACNL1A4 gene.
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Affiliation(s)
- Y Takiyama
- Department of Neurology, Jichi Medical School, Tochigi, Japan.
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56
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Iughetti P, Otto PA, Zatz M, Bueno MRP, Marie SK. Different behavior in the paternally vs. maternally inherited mutated allele in Brazilian Machado-Joseph (MJD1) Families. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1096-8628(19980518)77:3<246::aid-ajmg11>3.0.co;2-g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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57
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Yabe I, Sasaki H, Matsuura T, Takada A, Wakisaka A, Suzuki Y, Fukazawa T, Hamada T, Oda T, Ohnishi A, Tashiro K. SCA6 mutation analysis in a large cohort of the Japanese patients with late-onset pure cerebellar ataxia. J Neurol Sci 1998; 156:89-95. [PMID: 9559993 DOI: 10.1016/s0022-510x(98)00009-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Spinocerebellar ataxia type 6 (SCA6) is caused by small CAG repeat expansion in the gene encoding the alpha1A-voltage-dependent-calcium channel subunit (CACNLIA4) on chromosome 19p13, and is a subgroup of the late-onset pure cerebellar ataxia (ADCA III). To investigate the prevalence of SCA6 in the Japanese, we analyzed this mutation in 23 families and 12 probands with ADCA III. The specificity and stability of the CAG repeat were examined in additional individuals and families with other miscellaneous dominant SCAs. The CAG expansion of SCA6 gene was exclusively observed in 12 of 23 families (52%) and 12 proband cases with ADCA III, but not in others. The CAG repeat was 21-33 in the disease-associated alleles (n=56), and 4-18 in normal alleles (n=1148). Expanded alleles were stable during transmission, and a significant inverse correlation for CAG repeat number with age at onset was noted. Our results indicate that SCA6 shares approximately half of the ADCA III in the Japanese, and that gene mutations causing the remaining, have yet to be identified.
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Affiliation(s)
- I Yabe
- Department of Neurology, Hokkaido University School of Medicine, Sapporo, Japan
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58
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Ikeuchi T, Sanpei K, Takano H, Sasaki H, Tashiro K, Cancel G, Brice A, Bird TD, Schellenberg GD, Pericak-Vance MA, Welsh-Bohmer KA, Clark LN, Wilhelmsen K, Tsuji S. A novel long and unstable CAG/CTG trinucleotide repeat on chromosome 17q. Genomics 1998; 49:321-6. [PMID: 9598323 DOI: 10.1006/geno.1998.5266] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using the direct identification of repeat expansion and cloning technique, we cloned a novel long CAG/CTG trinucleotide repeat on chromosome 17. Using radiation hybrid panels, the CAG/CTG repeat was mapped to chromosome 17q. The CAG/CTG repeat is highly polymorphic, with a heterozygosity of 85%, and exhibits a bimodal distribution (allele S, 10-26 repeat units, and allele L, 50-92 repeat units). The CAG/CTG repeat of allele L exhibited intergenerational instabilities, which are more prominent in maternal transmission than in paternal transmission. Analyses of Northern blot and RT-PCR indicate that the repeat is transcribed. Although the size of the CAG/CTG repeat of allele L is within the range of the expanded CAG repeat of disease-causing genes, we did not detect any association of allele L with various neurodegenerative diseases, including frontotemporal dementia and parkinsonism, mapped to 17q21-q23.
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Affiliation(s)
- T Ikeuchi
- Department of Neurology, Niigata University, Japan
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59
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Løkkegaard T, Nielsen JE, Hasholt L, Fenger K, Werdelin L, Tranebjaerg L, Lauritzen M, Colding-Jørgensen E, Grønbech-Jensen M, Henriksen OA, Sørensen SA. Machado-Joseph disease in three Scandinavian families. J Neurol Sci 1998; 156:152-7. [PMID: 9588850 DOI: 10.1016/s0022-510x(98)00081-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Machado-Joseph disease (MJD) is an autosomal dominantly inherited neurodegenerative disorder characterized by varying age of onset and pronounced phenotypic heterogeneity. The clinical core features include gait ataxia, external ophthalmoplegia, nystagmus, and bulging eyes. Recently, Kawagushi et al. (1994) cloned the MJD1 gene on chromosome 14 and MJD turned out to be the fifth neurodegenerative disease caused by an unstable CAG repeat expansion. We have studied two large Danish families and one Norwegian family with MJD. Three features not previously associated with MJD are reported: dementia, generalized muscle and joint pain, and in one case neuropathological examination revealed atrophy of the inferior olives. We found a significant inverse correlation between age of onset and the length of the CAG repeat expansion, and anticipation is described through four succeeding generations. Instability of the CAG repeat expansion was most pronounced at paternal transmission.
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Affiliation(s)
- T Løkkegaard
- Institute of Medical Biochemistry and Genetics, The Panum Institute, University of Copenhagen, Denmark
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60
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Silveira I, Coutinho P, Maciel P, Gaspar C, Hayes S, Dias A, Guimarães J, Loureiro L, Sequeiros J, Rouleau GA. Analysis of SCA1, DRPLA, MJD, SCA2, and SCA6 CAG repeats in 48 Portuguese ataxia families. AMERICAN JOURNAL OF MEDICAL GENETICS 1998; 81:134-8. [PMID: 9613852 DOI: 10.1002/(sici)1096-8628(19980328)81:2<134::aid-ajmg3>3.0.co;2-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The spinocerebellar ataxias (SCAs) are clinically and genetically a heterogeneous group of neurodegenerative disorders. To date, eight different loci causing SCA have been identified: SCA1, SCA2, Machado-Joseph disease (MJD)/SCA3, SCA4, SCA5, SCA6, SCA7, and dentatorubropallidoluysian atrophy (DRPLA). Expansion of a CAG repeat in the disease genes has been found in five of these disorders. To estimate the relative frequencies of the SCA1, DRPLA, MJD, SCA2, and SCA6 mutations among Portuguese ataxia patients, we collected DNA samples from 48 ataxia families and performed polymerase chain reaction (PCR) amplification of the CAG repeat mutations on chromosomes 6p, 12p, 14q, 12q, and 19p, respectively. Fifty-five individuals belonging to 34 dominant families (74%) had an expanded CAG repeat at the MJD gene. In five individuals from two kindreds with a dominant pattern of inheritance (4%), an expanded CAG repeat at the SCA2 gene was found. In MJD patients, the normal allele size ranged from 13 to 41, whereas the mutant alleles contained 65 to 80 repeats. For the SCA2 patients, normal alleles had 22 or 23, while expanded alleles had between 36 and 47 CAG units. We did not find the SCA1, DRPLA, or SCA6 mutations in our group of families. The MJD mutation remains the most common cause of SCA in Portugal, while a small number of cases are caused by mutations at the SCA2 gene, and 22% are due to still unidentified genes.
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Affiliation(s)
- I Silveira
- Centre for Research in Neurosciences, McGill University and The Montreal General Hospital Research Institute, Québec, Canada
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61
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Takiyama Y, Shimazaki H, Morita M, Soutome M, Sakoe K, Esumi E, Muramatsu S, Yoshida M, Igarashi S, Tanaka H, Tsuji S, Sasaki H, Wakisaka A, Nakano I, Nishizawa M. Maternal anticipation in Machado-Joseph disease (MJD): some maternal factors independent of the number of CAG repeat units may play a role in genetic anticipation in a Japanese MJD family. J Neurol Sci 1998; 155:141-5. [PMID: 9562258 DOI: 10.1016/s0022-510x(98)00012-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We studied the relationship between the number of CAG repeat units in the MJD1 gene and clinical features of Machado-Joseph disease (MJD) in eight patients from two generations of a Japanese MJD family. Because of lack of characteristic clinical signs of MJD such as dystonia, bulging eyes or facial myokymia, clinical diagnosis of MJD in this family was difficult to make prior to molecular testing for the CAG repeat expansion in the MJD1 gene. All the patients exhibited maternal transmission of MJD, and the intergenerational change in the number of CAG repeat units in the MJD1 gene was very small (+0.5+/-0.3, mean+/-S.E.M., n=4) in spite of marked genetic anticipation (-17.0 years/generation). In the present family, the degree of anticipation per repeat unit in maternal transmissions was much larger than that in maternal transmissions in the other six MJD families. This indicates that some maternal factors other than the increase of the number of CAG repeat units, which is known to be the basis of anticipation, may play a role in genetic anticipation in this MJD family.
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Affiliation(s)
- Y Takiyama
- Department of Neurology, Jichi Medical School, Tochigi, Japan.
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62
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Onodera O, Idezuka J, Igarashi S, Takiyama Y, Endo K, Takano H, Oyake M, Tanaka H, Inuzuka T, Hayashi T, Yuasa T, Ito J, Miyatake T, Tsuji S. Progressive atrophy of cerebellum and brainstem as a function of age and the size of the expanded CAG repeats in the MJD1 gene in Machado-Joseph disease. Ann Neurol 1998; 43:288-96. [PMID: 9506544 DOI: 10.1002/ana.410430305] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disease characterized by cerebellar ataxia associated to varying degrees with pyramidal signs, extrapyramidal signs, or peripheral amyotrophy. It is caused by unstable expansion of the CAG repeat in the MJD1 gene on chromosome 14q32.1. To determine how the neurodegenerative process in the central nervous system of patients with MJD correlates with the size of expanded CAG repeats in the MJD1 gene and other factors, we performed detailed quantitative analyses of findings of magnetic resonance imaging of the central nervous system of 21 patients with MJD of various ages and with various sizes of expanded CAG repeats. We found that atrophy of the brainstem and cerebellar vermis in MJD patients is closely correlated not only with the size of expanded CAG repeat in the MJD1 gene but also with patient age, which suggests that the neurodegenerative process in MJD is regulated by the size of expanded CAG repeats as well as by the patient age.
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Affiliation(s)
- O Onodera
- Department of Neurology, Brain Research Institute, Niigata University, Japan
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63
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Maurer DJ, Benzow KA, Schut LJ, Ranum LP, Livingston DM. Comparison of expanded CAG repeat tracts in sperm and lymphocyte DNA from Machado Joseph disease and spinocerebellar ataxia type I patients. Hum Mutat 1998; Suppl 1:S74-7. [PMID: 9452047 DOI: 10.1002/humu.1380110126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- D J Maurer
- Department of Biochemistry, University of Minnesota Medical School, Minneapolis 55455, USA
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64
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Schweitzer JK, Livingston DM. Expansions of CAG repeat tracts are frequent in a yeast mutant defective in Okazaki fragment maturation. Hum Mol Genet 1998; 7:69-74. [PMID: 9384605 DOI: 10.1093/hmg/7.1.69] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
To understand the causes of CAG repeat tract changes that occur in the passage of human disease alleles, we are studying the effect of replication and repair mutations on CAG repeat tracts embedded in a yeast chromosome. In this report, we examine the effect of a mutation in the RTH1/RAD27 gene encoding a deoxyribonuclease needed for removal of excess nucleotides at the 5'-end of Okazaki fragments. Deletion of the RTH1/RAD27 gene has two effects on CAG tracts. First, the rth1/rad27 mutation destabilizes CAG tracts. Second, although most tract length changes in wild-type yeast cells are tract contractions, approximately half of the changes that occur as a result of the rth1/rad27 mutation are expansions of one or more repeat units. These results support the hypothesis that tract expansions that occur during passage of human disease alleles bearing expanded CAG tracts result from excess DNA synthesis on the lagging strand of replication.
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Affiliation(s)
- J K Schweitzer
- Department of Biochemistry, 4-225 Millard Hall, 435 Delaware Street SE, University of Minnesota, Minneapolis, MN 55455-0347, USA
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65
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Abstract
One of us (MP) learned about the mapping of Huntington disease gene to chromosome 4 from the late Dr. Anita Harding. She got the news over the phone from her London office during a visit to Italy for a meeting on hereditary ataxias. In Britain, they receive Nature at least a week earlier than us. Dr. Harding was very excited, and she immediately said that that was the way to go if we wanted to understand the causes of hereditary ataxias, classify these diseases in a rational way, and eventually find a treatment. At that time, the challenge seemed, and indeed was, formidable. No clue was then available about the genetic basis of what Dr. Harding aptly called "hereditary ataxias of unknown cause," their classification was confused and controversial, and all attempts to find specific biochemical abnormalities had failed. Fourteen years later, the success of the molecular genetic studies is astounding. The defective genes have been identified for Friedreich ataxia, the major recessive "hereditary ataxia of unknown cause," and for five dominantly inherited "hereditary ataxias of unknown cause." Three more dominant ataxia genes have been mapped. The molecular pathogenesis of the dominant ataxias begins to be unraveled and animal models have been and are being developed. Information is also quickly accumulating about the defective protein in Friedreich ataxia. Direct molecular diagnosis is now possible. Classification has been revolutionized. Diagnostic criteria are being redefined in the light of the molecular discoveries. The goal of this review, dedicated to the memory of the late Dr. Harding, is to offer a concise summary of current knowledge about the molecular genetics of some of the hereditary ataxias that used to be classified as of "unknown cause."
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Affiliation(s)
- M Pandolfo
- Centre de Recherche Louis-Charles Simard, Montréal, Québec, Canada
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66
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Ikeuchi T, Takano H, Koide R, Horikawa Y, Honma Y, Onishi Y, Igarashi S, Tanaka H, Nakao N, Sahashi K, Tsukagoshi H, Inoue K, Takahashi H, Tsuji S. Spinocerebellar ataxia type 6: CAG repeat expansion in alpha1A voltage-dependent calcium channel gene and clinical variations in Japanese population. Ann Neurol 1997; 42:879-84. [PMID: 9403480 DOI: 10.1002/ana.410420609] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Autosomal dominant spinocerebellar ataxias (SCAs) are clinically and genetically a heterogeneous group of neurodegenerative disorders. Recently, mild CAG repeat expansion in the alpha1A voltage-dependent calcium channel gene has been found to be associated with a type of autosomal dominant SCA (SCA6). We analyzed 98 Japanese families with autosomal dominant SCAs, for whom CAG repeat expansions of the SCA1, SCA2, Machado-Joseph disease/SCA3, and dentatorubral-pallidoluysian atrophy genes were excluded, and 5 apparently sporadic cases of cortical cerebellar atrophy. The diagnosis of SCA6 was confirmed in 30 families (31%) comprising 47 affected individuals and 1 sporadic case. The size of expanded CAG repeats ranged from 21 to 26 repeat units and was found to be correlated inversely with age at onset. We identified 2 SCA6 patients homozygous for expanded CAG repeats, whose ages at onset were earlier than the 95% lower confidence level, suggesting the presence of a gene dosage effect of expanded CAG repeat. Ataxia is the most common initial symptom found in 45 of the 48 patients. Patients with a prolonged disease course showed other accompanying clinical features including dystonic postures, involuntary movements, and abnormalities in tendon reflexes.
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Affiliation(s)
- T Ikeuchi
- Department of Neurology, Brain Research Institute, Niigata University, Japan
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67
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Arruda WO, Teive HA. [Hereditary cerebellar ataxias: from hammer to genetics]. ARQUIVOS DE NEURO-PSIQUIATRIA 1997; 55:666-76. [PMID: 9629425 DOI: 10.1590/s0004-282x1997000400027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The hereditary ataxias comprise a complex group of neurological disorders involving the cerebellum and its connections. Several classifications based on clinical and/or pathological data have been only partially successful. Recent progress in molecular genetics has identified the genic loci of hereditary ataxias and has allowed a more precise diagnosis of distinct genetic diseases. Trinucleotide repeat expansions has been recognized as a mechanism of disease in some autosomal dominant spinocerebellar ataxias (ADCA) (SCA1 to SCA7), including Machado-Joseph disease/SCA3, probably the most common form of ADCA in South Brazil, and Friedreich ataxia (GAA expansion-chromosome 9p). Familial alpha-tocopherol deficiency (chromosome 8q) may have a Friedreich ataxia phenotype and responds to the oral supplementation with vitamin E. Familial episodic ataxias with (EA1-chromosome 12p) and without (chromosome 19p-EA2) myokimia were identified, the first one caused by point mutations in the gene encoding the KCNA1 potassium voltage-gated channel. The gene responsible for ataxia-teleangiectasia (chromosome 11q) was found to encode a putative DNA binding protein kinase (ATM), related to the cell cycle control. One to 3% of the population are heterozygotic ATM gen carry and pose a higher risk of cancer when exposed to ionizing radiation. Molecular biology has provided us with useful tools to diagnosis and genetic counseling and, hopefully, will provide us with a better understanding of the pathogenesis and eventual treatment of the several forms of hereditary ataxias.
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Affiliation(s)
- W O Arruda
- Departamento de Clínica Médica, Universidade Federal do Paraná (UFPR), Brasil
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68
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Goto J, Watanabe M, Ichikawa Y, Yee SB, Ihara N, Endo K, Igarashi S, Takiyama Y, Gaspar C, Maciel P, Tsuji S, Rouleau GA, Kanazawa I. Machado-Joseph disease gene products carrying different carboxyl termini. Neurosci Res 1997; 28:373-7. [PMID: 9274833 DOI: 10.1016/s0168-0102(97)00056-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Three cDNA clones for the Machado-Joseph disease gene (MJD1) were isolated, two of which have a new exon sequence and a distinct 3' terminal nucleotide sequence resulting in a new carboxyl terminal domain in the translated product. The nucleotide sequence of the other one is similar to the previously published one except for five polymorphisms, one of which is a single nucleotide substitution resulting in a change from the stop codon (TAA; allele A) to a tyrosine residue (TAC; allele C). Genetic analysis results suggest that Japanese MJD mutations are associated with allele A.
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Affiliation(s)
- J Goto
- Department of Neurology, Institute for Brain Research, Faculty of Medicine, University of Tokyo, Japan
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69
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Ishikawa K, Tanaka H, Saito M, Ohkoshi N, Fujita T, Yoshizawa K, Ikeuchi T, Watanabe M, Hayashi A, Takiyama Y, Nishizawa M, Nakano I, Matsubayashi K, Miwa M, Shoji S, Kanazawa I, Tsuji S, Mizusawa H. Japanese families with autosomal dominant pure cerebellar ataxia map to chromosome 19p13.1-p13.2 and are strongly associated with mild CAG expansions in the spinocerebellar ataxia type 6 gene in chromosome 19p13.1. Am J Hum Genet 1997; 61:336-46. [PMID: 9311738 PMCID: PMC1715894 DOI: 10.1086/514867] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Autosomal dominant cerebellar ataxia is a group of clinically and genetically heterogeneous disorders. We carried out genomewide linkage analysis in 15 families with autosomal dominant pure cerebellar ataxia (ADPCA). Evidence for linkage to chromosome 19p markers was found in nine families, and combined multipoint analysis refined the candidate region to a 13.3-cM interval in 19p13.1-p13.2. The remaining six families were excluded for this region. Analysis of CAG-repeat expansion in the alpha1A-voltage-dependent calcium channel (CACNL1A4) gene lying in 19p13.1, recently identified among 8 small American kindreds with ADPCA (spinocerebellar ataxia type 6 [SCA6]), revealed that 8 of the 15 families studied had similar, very small expansion in this gene: all affected individuals had larger alleles (range of CAG repeats 21-25), compared with alleles observed in neurologically normal Japanese (range 5-20 repeats). Inverse correlation between the CAG-repeat number and the age at onset was found in affected individuals with expansion. The number of CAG repeats in expanded chromosomes was completely stable within each family, which was consistent with the fact that anticipation was not statistically proved in the SCA6 families that we studied. We conclude that more than half of Japanese cases of ADPCA map to 19p13.1-p13.2 and are strongly associated with the mild CAG expansion in the SCA6/CACNL1A4 gene.
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Affiliation(s)
- K Ishikawa
- Department of Neurology, Institute of Clinical Medicine, University of Tsukuba, Japan
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70
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Wellington CL, Brinkman RR, O'Kusky JR, Hayden MR. Toward understanding the molecular pathology of Huntington's disease. Brain Pathol 1997; 7:979-1002. [PMID: 9217979 PMCID: PMC8098409 DOI: 10.1111/j.1750-3639.1997.tb00897.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Huntington's Disease (HD) is caused by expansion of a CAG trinucleotide beyond 35 repeats within the coding region of a novel gene. Recently, new insights into the relationship between CAG expansion in the HD gene and pathological mechanisms have emerged. Survival analysis of a large cohort of affected and at-risk individuals with CAG sizes between 39 and 50 repeats have yielded probability curves of developing HD symptoms and dying of HD by a certain age. Animals transgenic for the first exon of huntingtin with large CAG repeats lengths have been reported to have a complex neurological phenotype that bears interesting similarities and differences to HD. The repertoire of huntingtin-interacting proteins continues to expand with the identification of HIP1, a protein whose yeast homologues have known functions in regulating events associated with the cytoskeleton. The ability of huntingtin to interact with two of its four known protein partners appears to be influenced by CAG length. Caspase 3 (apopain), a key cysteine protease known to play a seminal role in neural apoptosis, has also been demonstrated to specifically cleave huntingtin in a CAG length-dependent manner. Many of these features are combined in a model suggesting mechanisms by which the pathogenesis of HD may be initiated. The development of appropriate in vitro and animal models for HD will allow the validity of these models to be tested.
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Affiliation(s)
- C L Wellington
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada
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71
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Stevanin G, Lebre AS, Mathieux C, Cancel G, Abbas N, Didierjean O, Dürr A, Trottier Y, Agid Y, Brice A. Linkage disequilibrium between the spinocerebellar ataxia 3/Machado-Joseph disease mutation and two intragenic polymorphisms, one of which, X359Y, affects the stop codon. Am J Hum Genet 1997; 60:1548-52. [PMID: 9199580 PMCID: PMC1716136 DOI: 10.1016/s0002-9297(07)64251-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
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72
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Cancel G, Dürr A, Didierjean O, Imbert G, Bürk K, Lezin A, Belal S, Benomar A, Abada-Bendib M, Vial C, Guimarães J, Chneiweiss H, Stevanin G, Yvert G, Abbas N, Saudou F, Lebre AS, Yahyaoui M, Hentati F, Vernant JC, Klockgether T, Mandel JL, Agid Y, Brice A. Molecular and clinical correlations in spinocerebellar ataxia 2: a study of 32 families. Hum Mol Genet 1997; 6:709-15. [PMID: 9158145 DOI: 10.1093/hmg/6.5.709] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Spinocerebellar ataxia 2 (SCA2) is caused by the expansion of an unstable CAG repeat encoding a polyglutamine tract. One hundred and eighty four index patients with autosomal dominant cerebellar ataxia type I were screened for this mutation. We found expansion in 109 patients from 30 families of different geographical origins (15%) and in two isolated cases with no known family histories (2%). The SCA2 chromosomes contained from 34 to 57 repeats and consisted of a pure stretch of CAG, whereas all tested normal chromosomes (14-31 repeats), except one with 14 repeats, were interrupted by 1-3 repeats of CAA. As in other diseases caused by unstable mutations, a strong negative correlation was observed between the age at onset and the size of the CAG repeat (r = -0.81). The frequency of several clinical signs such as myoclonus, dystonia and myokymia increased with the number of CAG repeats whereas the frequency of others was related to disease duration. The CAG repeat was highly unstable during transmission with variations ranging from -8 to +12, and a mean increase of +2.2, but there was no significant difference according to the parental sex. This instability was confirmed by the high degree of gonadal mosaicism observed in sperm DNA of one patient.
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73
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Soong B, Cheng C, Liu R, Shan D. Machado-Joseph disease: clinical, molecular, and metabolic characterization in Chinese kindreds. Ann Neurol 1997; 41:446-52. [PMID: 9124801 DOI: 10.1002/ana.410410407] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Machado-Joseph disease, an autosomal dominant multisystem motor degeneration, has been described mainly in people of Portuguese descent. Our report documents the presence of Machado-Joseph disease in the Chinese population, based on the specific molecular marker of a CAG repeat array in the 3' end of the MJD gene. We screened 21 Chinese families with dominant spinocerebellar ataxia. The results showed that Machado-Joseph disease with CAG expansion accounted for 52% of families with autosomal dominant cerebellar ataxia in this series. The clinical characteristics, besides the well-documented cerebellar ataxia, dysarthria, nystagmus, corticospinal dysfunctions, a variable degree of facial muscle fasciculation, and proprioceptive loss, included loss of optokinetic nystagmus and autonomic nervous system dysfunction. The CAG repeat number in the MJD gene ranged from 14 to 39 among normal alleles, and from 63 to 81 among MJD alleles. There was a strong inverse correlation (gamma = -0.77) between number of CAG repeats and age at symptom onset, accounting for 60% of the variance of age at onset. A strong clinical anticipation of age at onset existed in successive generations. Mild instabilities of expanded CAG repeat numbers during meiotic transmission occurred, with no significant difference according to the gender of the transmitting parent. Finally, brain metabolism in Machado-Joseph disease, studied with positron emission tomography, was characterized by significant progressive regional hypometabolism in the occipital cortex, as well as the cerebellar hemispheres, vermis, and brainstem.
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Affiliation(s)
- B Soong
- Department of Neurology, National Yang-Ming University School of Medicine and National Defense Medical Center, Taipei, Taiwan, Republic of China
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74
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Hashida H, Goto J, Kurisaki H, Mizusawa H, Kanazawa I. Brain regional differences in the expansion of a CAG repeat in the spinocerebellar ataxias: dentatorubral-pallidoluysian atrophy, Machado-Joseph disease, and spinocerebellar ataxia type 1. Ann Neurol 1997; 41:505-11. [PMID: 9124808 DOI: 10.1002/ana.410410414] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Three autosomal dominant spinocerebellar ataxias, dentatorubral-pallidoluysian atrophy (DRPLA), Machado-Joseph disease (MJD), and spinocerebellar ataxia type 1 (SCA1), are associated with the expansion of a CAG repeat in the respective genes. To investigate the association between CAG repeat expansion and neuropathological findings, we analyzed several brain regions from 9 cases of DRPLA, 3 cases of MJD, and 1 case of SCA1. We found that the expanded alleles were smaller in the cerebellar cortex than in other brain regions, such as the frontal cortex, in these three diseases. The discrepancy in the expanded CAG repeat length between cerebellar cortex and other tissues was most prominent in DRPLA, and especially in cases of adult-onset DRPLA. A significant correlation was found between the age at onset of DRPLA and the size of the CAG repeat expansion. Cerebella of DRPLA patients were microscopically dissected into three layers, the molecular and granular layers and the white matter, which were analyzed separately. The lower level of CAG repeat expansion in DRPLA cerebella was representative of CAG repeat expansion in the granule cells. The microdissected samples of the granular layer of the hippocampal formation, which is densely packed with neuronal cells, revealed that the degree of CAG repeat expansion in this layer was similar to that in the cerebellum. These observations suggest that granule cells in the cerebellum and hippocampus have low levels of CAG repeat expansion, and that other types of cells exhibit a higher level of CAG repeat expansion, in spinocerebellar ataxias.
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Affiliation(s)
- H Hashida
- Department of Neurology, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Japan
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75
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Gusella JF, Persichetti F, MacDonald ME. The Genetic Defect Causing Huntington’s Disease: Repeated in Other Contexts? Mol Med 1997. [DOI: 10.1007/bf03401677] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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76
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Schweitzer JK, Livingston DM. Destabilization of CAG trinucleotide repeat tracts by mismatch repair mutations in yeast. Hum Mol Genet 1997; 6:349-55. [PMID: 9147637 DOI: 10.1093/hmg/6.3.349] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
To examine the genetic factors that affect the stability of disease-associated trinucleotide repeats, we have assessed the stability of CAG repeats in yeast strains with mutations in the mismatch repair system. We have found that both pms1 and msh2 mutations destabilize repeat tracts. Destabilization is evidenced both by the increased frequency of repeat length changes and in the pattern of changes that are observed. In wild-type cells repeats are relatively stable when CAG serves as the lagging strand template but relatively unstable when CTG serves as the lagging strand template. Large contractions in repeat length are the most common change. In pms1 and msh2 mutants the relatively stable tracts incur more tract length changes. In addition, many small deletions and some small additions, most often of one repeat unit, are frequent in repeats of the stable orientation. These small changes also are seen as a new class of events that occur in repeats in the unstable orientation. The results show that in yeast the mismatch repair system prevents small changes from occurring but cannot prevent larger changes from occurring.
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Affiliation(s)
- J K Schweitzer
- Department of Biochemistry, University of Minnesota, Minneapolis 55455-0347, USA
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77
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Matsumura R, Takayanagi T, Murata K, Futamura N, Fujimoto Y. Autosomal dominant cerebellar ataxias in the Kinki area of Japan. THE JAPANESE JOURNAL OF HUMAN GENETICS 1996; 41:399-406. [PMID: 9088110 DOI: 10.1007/bf01876330] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The autosomal dominant cerebellar ataxias are a heterogeneous group of neurodegenerative disorders characterized by slowly progressive cerebellar ataxia. Recently, among the ataxias, spinocerebellar ataxia type 1 (SCA1), Machado-Joseph disease (MJD) and dentatorubral-pallidoluysian atrophy have been found to be caused by expansion of a CAG trinucleotide repeat in the coding region of the disease genes. We have analyzed the CAG repeats of 67 patients from 47 families with dominantly inherited ataxia who lived in the Kinki area of Japan. The following results were obtained. First, 31 patients from 22 families were found to be positive for the MJD repeat expansion, indicating that MJD is the most common dominantly inherited ataxia in the Kinki area of Japan. Second, no SCA1 repeat expansion was found among the families studied. This presents a striking contrast to the fact that there are many families with SCA1 in Hokkaido and the Tohoku area of Japan. These findings suggest geographic variation in autosomal dominant cerebellar ataxias in Japan.
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Affiliation(s)
- R Matsumura
- Department of Neurology, Nara Medical University, Japan
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78
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Schöls L, Amoiridis G, Epplen JT, Langkafel M, Przuntek H, Riess O. Relations between genotype and phenotype in German patients with the Machado-Joseph disease mutation. J Neurol Neurosurg Psychiatry 1996; 61:466-70. [PMID: 8937340 PMCID: PMC1074043 DOI: 10.1136/jnnp.61.5.466] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Machado-Joseph disease (MJD) is an autosomal dominant cerebellar ataxia with extensive phenotypic variability originally described in families of Portuguese ancestry. Recently, the mutation causing the disease has been identified as an expanded CAG trinucleotide repeat. In this study relations between genotype and phenotype were investigated. METHODS A series of 180 German patients with degenerative forms of ataxia were clinically and genetically examined. Patients bearing the MJD mutation were assigned to three phenotypes: phenotype 1 characterised by early onset and dystonia or pronounced rigidity associated with ataxia and spasticity. Main symptoms in phenotype 2 were ataxia and spasticity. In phenotype 3 onset was relatively late and peripheral neuropathy accompanied ataxia. Clinical and molecular data were correlated. RESULTS An expanded CAG array was found in 42 patients from 22 families. Repeat length of CAG varied between 67 and 80 CAG motifs and showed an inverse correlation with the age of onset. For the development of phenotype 1 early onset (< 20 years) seemed more decisive than extensive repeat length. Phenotype 2 was present in all patients with more than 73 CAG motifs and onset between 20 and 40. Phenotype 3 developed in most patients with less than 73 CAG motifs and onset was regularly beyond the age of 40. Intrafamilial variability of both repeat length and phenotype was large reflecting meiotic instability of the expanded CAG repeat. CONCLUSIONS The MJD mutation is the most frequent cause of dominantly inherited ataxia in Germany. Variations in repeat lengths substantially influence age of onset as well as phenotype but cannot explain why MJD characteristics of Portuguese families such as "bulging eyes", dystonia, and rigidity are essentially missing in German families. Despite the genotypic and phenotypic relations found in this study a reliable individual prognosis of the course of the disease is not possible at a presymptomatic stage.
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Affiliation(s)
- L Schöls
- Department of Neurology, St Josef Hospital, Ruhr-University, Bochum, Germany
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79
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MESH Headings
- Cerebellar Ataxia/genetics
- Chromosomes, Human, Pair 11
- Chromosomes, Human, Pair 12
- Chromosomes, Human, Pair 14
- Chromosomes, Human, Pair 16
- Chromosomes, Human, Pair 21
- Chromosomes, Human, Pair 3
- Friedreich Ataxia/genetics
- Genetic Linkage
- Humans
- Point Mutation
- RNA, Messenger
- Transcription, Genetic
- Trinucleotide Repeats/genetics
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80
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Endo K, Sasaki H, Wakisaka A, Tanaka H, Saito M, Igarashi S, Takiyama Y, Sanpei K, Iwabuchi K, Suzuki Y, Onari K, Suzuki T, Weissenbach J, Weber JL, Nomura Y, Segawa M, Nishizawa M, Tsuji S. Strong linkage disequilibrium and haplotype analysis in Japanese pedigrees with Machado-Joseph disease. AMERICAN JOURNAL OF MEDICAL GENETICS 1996; 67:437-44. [PMID: 8886159 DOI: 10.1002/(sici)1096-8628(19960920)67:5<437::aid-ajmg1>3.0.co;2-h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To identify the markers tightly linked to Machado-Joseph disease (MJD) and to investigate whether a limited number of ancestral chromosomes are shared by Japanese MJD pedigrees, a detailed linkage analysis employing D14S55, D14S48, D14S67, D14S291, D14S280, AFM343vf1, D14S81, D14S265, D14S62, and D14S65 was performed. The results of multipoint linkage analysis as well as detection of critical recombination events indicate that the gene for MJD is localized in a 4-cM region between D14S280-D14S81. We found strong linkage disequilibria at AFM343vf1 and D14S81, and association of a few common haplotypes with MJD. These results indicate that there is an obvious founder effect in Japanese MJD and suggest the possibility of the existence of predisposing haplotypes which are prone to expansions of CAG repeats.
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Affiliation(s)
- K Endo
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Japan
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81
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Tsuji S. Unstable expansion of triplet repeats as a new disease mechanism for neurodegenerative diseases. THE JAPANESE JOURNAL OF HUMAN GENETICS 1996; 41:279-90. [PMID: 8996963 DOI: 10.1007/bf01913170] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- S Tsuji
- Department of Neurology, Niigata University, Japan
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82
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Ikeda H, Yamaguchi M, Sugai S, Aze Y, Narumiya S, Kakizuka A. Expanded polyglutamine in the Machado-Joseph disease protein induces cell death in vitro and in vivo. Nat Genet 1996; 13:196-202. [PMID: 8640226 DOI: 10.1038/ng0696-196] [Citation(s) in RCA: 416] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Recently, we identified a novel gene, MJD1, which contains an expanded CAG triplet repeat in Machado-Joseph disease. Here we report the induction of apoptosis in cultured cells expressing a portion of the MJD1 gene that includes the expanded CAG repeats. Cell death occurs only when the CAG repeat is translated into polyglutamine residues, which apparently precipitate in large covalently modified forms. We also created ataxic transgenic mice by expressing the expanded polyglutamine stretch in Purkinje cells. Our results demonstrate the potential involvement of the expanded polyglutamine as the common aetiological agent for inherited neurodegenerative diseases with CAG expansions.
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Affiliation(s)
- H Ikeda
- Department of Pharmacology, Kyoto University Faculty of Medicine, Japan
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83
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Iughetti P, Zatz M, Bueno MR, Marie SK. Different origins of mutations at the Machado-Joseph locus (MJD1). J Med Genet 1996; 33:439. [PMID: 8733063 PMCID: PMC1050622 DOI: 10.1136/jmg.33.5.439] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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84
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Dürr A, Stevanin G, Cancel G, Duyckaerts C, Abbas N, Didierjean O, Chneiweiss H, Benomar A, Lyon-Caen O, Julien J, Serdaru M, Penet C, Agid Y, Brice A. Spinocerebellar ataxia 3 and Machado-Joseph disease: clinical, molecular, and neuropathological features. Ann Neurol 1996; 39:490-9. [PMID: 8619527 DOI: 10.1002/ana.410390411] [Citation(s) in RCA: 310] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Patients with spinocerebellar ataxia 3 (SCA3) and Machado-Joseph disease (MJD) carry an expanded CAG repeat in the MJD1 gene. One hundred twenty families of different geographic origin with autosomal dominant cerebellar ataxia (ADCA) type I were tested. Thirty-four families (126 patients) carried an expanded CAG repeat. The expanded and the normal allele did not overlap and the repeat was unstable during transmission, with variation in the size of the CAG length ranging from -8 to +5 and a mean expansion of 0.86 repeats without differences according to the parental sex. There was a combined effect of the number of CAG repeats of the expanded and normal allele on the age at onset, which accounted for 70% of its variability. The length of the CAG repeat influenced the frequency of clinical signs associated with cerebellar ataxia, such as abnormal tendon reflexes or decreased vibration sense, whereas the interindividual variation of supranuclear ophthalmoplegia, sphincter and swallowing difficulties, and amyotrophy was mostly determined by different disease durations. We compared the clinical profile of 91 SCA3/MJD patients with 51 SCA1 and 32 SCA2 patients. There were striking differences between the SCA3/MJD and SCA2 but not with SCA1 groups of patients. Despite their clinical similarities, distinct neuropathological features were observed in 2 SCA3/MJD and 2 SCA1 patients.
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Affiliation(s)
- A Dürr
- INSERM U289, Hôpital de la Salpêtrière, Paris, France
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85
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Petronis A, Heng HH, Tatuch Y, Shi XM, Klempan TA, Tsui LC, Ashizawa T, Surh LC, Holden JJ, Kennedy JL. Direct detection of expanded trinucleotide repeats using PCR and DNA hybridization techniques. AMERICAN JOURNAL OF MEDICAL GENETICS 1996; 67:85-91. [PMID: 8678121 DOI: 10.1002/(sici)1096-8628(19960216)67:1<85::aid-ajmg15>3.0.co;2-l] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Recently, unstable trinucleotide repeats have been shown to be the etiologic factor in seven neuropsychiatric diseases, and they may play a similar role in other genetic disorders which exhibit genetic anticipation. We have tested one polymerase chain reaction (PCR)-based and two hybridization-based methods for direct detection of unstable DNA expansion in genomic DNA. This technique employs a single primer (asymmetric) PCR using total genomic DNA as a template to efficiently screen for the presence of large trinucleotide repeat expansions. High-stringency Southern blot hybridization with a PCR-generated trinucleotide repeat probe allowed detection of the DNA fragment containing the expansion. Analysis of myotonic dystrophy patients containing different degrees of (CTG)n expansion demonstrated the identification of the site of trinucleotide instability in some affected individuals without any prior information regarding genetic map location. The same probe was used for fluorescent in situ hybridization and several regions of (CTG)n/(CAG)n repeats in the human genome were detected, including the myotonic dystrophy locus on chromosome 19q. Although limited at present to large trinucleotide repeat expansions, these strategies can be applied to directly clone genes involved in disorders caused by large expansions of unstable DNA.
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Affiliation(s)
- A Petronis
- Neurogenetics Section, Hospital for Sick Children, Toronto
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86
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Limprasert P, Nouri N, Heyman RA, Nopparatana C, Kamonsilp M, Deininger PL, Keats BJ. Analysis of CAG repeat of the Machado-Joseph gene in human, chimpanzee and monkey populations: a variant nucleotide is associated with the number of CAG repeats. Hum Mol Genet 1996; 5:207-13. [PMID: 8824876 DOI: 10.1093/hmg/5.2.207] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder associated with an unstable and expanded CAG repeat. We analyzed this locus from various sources including MJD families, Acadian, African American, Caucasian, Greenland Inuit and Thai populations. The range of the CAG repeat size was 14-40 in the normal alleles while the MJD alleles contained 73-78 repeats in our studies. We found 25 different alleles on normal chromosomes with a heterozygosity of 0.86 in combined populations. The most common alleles were 23 (22.9%) and 14 (25.5%) repeats. We also examined 16 chimpanzees and various Old World monkeys: a pigtail macaque, a mangabey and 12 rhesus macaques. The DNA sequences surrounding the CAG repeat did not vary among species. The range of the number of the CAG repeats is 13-14 in macaques, 16 in mangabey and 14-20 in chimpanzees. Variant CAA or AAG triplets in the CAG repeat tracts were found in all 268 human, 28 monkey and 32 chimpanzee chromosomes. As reported in a previous study [Kawaguchi et al. (1994) Nature Genet. 8, 221-228] the common variant positions were the third (CAA), fourth (AAG) and sixth (CAA) positions. However, we found three human chromosomes containing CAG at the sixth position and the mangabey had AAG at the ninth position. In addition, we found CAG at the fourth position and AAG at the sixth position in all macaque chromosomes. The nucleotide following the CAG repeat tract was usually G in all species studied. However, we sometimes found C at this position in human and chimpanzee chromosomes. Interestingly, this variant C was found in all expanded chromosomes and in 54.5% of chromosomes with 27-40 CAG repeats but it was not found in any chromosomes with less than 20 CAG repeats. We hypothesize that the variant C may be associated with CAG repeat instability.
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Affiliation(s)
- P Limprasert
- Department of Biometry and Genetics, Louisana State University Medical Center, New Orleans 70112, USA
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87
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DeStefano AL, Farrer LA, Maciel P, Gaspar C, Rouleau GA, Coutinho P, Sequeiros J. Gender equality in Machado-Joseph disease. Nat Genet 1995; 11:118-9. [PMID: 7550334 DOI: 10.1038/ng1095-118b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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88
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Dürr A, Stevanin G, Cancel G, Abbas N, Chneiweiss H, Agid Y, Feingold J, Brice A. Gender equality in Machado-Joseph disease. Nat Genet 1995; 11:118-9. [PMID: 7550335 DOI: 10.1038/ng1095-118a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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89
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Tuite PJ, Rogaeva EA, St George-Hyslop PH, Lang AE. Dopa-responsive parkinsonism phenotype of Machado-Joseph disease: confirmation of 14q CAG expansion. Ann Neurol 1995; 38:684-7. [PMID: 7574470 DOI: 10.1002/ana.410380422] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The subtype IV of Machado-Joseph disease (MJD), characterized by parkinsonism variably combined with ataxia, distal atrophy, and sensory loss, has been all but ignored in recent reports of MJD, including those describing the molecular biologic substrate of the disease. We have demonstrated expansion of the CAG trinucleotide repeat of the MJD1 gene located on chromosome 14q32.1 in 2 patients of Azorean descent who presented with levodopa-responsive atypical parkinsonism. Previous publications have documented the presence of this expanded repeat in the other more common MJD phenotypes (I-III). To our knowledge, this is the first molecular biologic confirmation of the presence of the MJD1 gene in the subtype IV phenotype. Patients presenting with parkinsonism and peripheral neuropathy should be screened for this genetic defect.
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Affiliation(s)
- P J Tuite
- Morton and Gloria Shulman Movement Disorder Center, Toronto Hospital, Ontario, Canada
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