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Hoffman-Zacharska D, Sulek A. The New Face of Dynamic Mutation-The CAA [CAG]n CAA CAG Motif as a Mutable Unit in the TBP Gene Causative for Spino-Cerebellar Ataxia Type 17. Int J Mol Sci 2024; 25:8190. [PMID: 39125760 PMCID: PMC11312008 DOI: 10.3390/ijms25158190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Revised: 07/16/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
Since 1991, several genetic disorders caused by unstable trinucleotide repeats (TNRs) have been identified, collectively referred to as triplet repeat diseases (TREDs). They share a common mutation mechanism: the expansion of repeats (dynamic mutations) due to the propensity of repeated sequences to form unusual DNA structures during replication. TREDs are characterized as neurodegenerative diseases or complex syndromes with significant neurological components. Spinocerebellar ataxia type 17 (SCA17) falls into the former category and is caused by the expansion of mixed CAA/CAG repeats in the TBP gene. To date, a five-unit organization of this region [(CAG)3 (CAA)3] [(CAG)n] [CAA CAG CAA] [(CAG)n] [CAA CAG], with expansion in the second [(CAG)n] unit being the most common, has been proposed. In this study, we propose an alternative organization scheme for the repeats. A search of the PubMed database was conducted to identify articles reporting both the number and composition of GAC/CAA repeats in TBP alleles. Nineteen reports were selected. The sequences of all identified CAG/CAA repeats in the TBP locus, including 67 cases (probands and b relatives), were analyzed in terms of their repetition structure and stability in inheritance, if possible. Based on the analysis of three units [(CAG)3 (CAA)2] [CAA (CAG)n CAA CAG] [CAA (CAG)n CAA CAG], the organization of repeats is proposed. Detailed analysis of the CAG/CAA repeat structure, not just the number of repeats, in TBP-expanded alleles should be performed, as it may have a prognostic value in the prediction of stability/instability during transmission and the possible anticipation of the disease.
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Affiliation(s)
- Dorota Hoffman-Zacharska
- Department of Medical Genetics, Institute of Mother and Child, 02-106 Warsaw, Poland
- Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland;
| | - Anna Sulek
- Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland;
- Faculty of Medicine, Lazarski University, 02-662 Warsaw, Poland
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Rafehi H, Bennett MF, Bahlo M. Detection and discovery of repeat expansions in ataxia enabled by next-generation sequencing: present and future. Emerg Top Life Sci 2023; 7:349-359. [PMID: 37733280 PMCID: PMC10754322 DOI: 10.1042/etls20230018] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/29/2023] [Accepted: 09/12/2023] [Indexed: 09/22/2023]
Abstract
Hereditary cerebellar ataxias are a heterogenous group of progressive neurological disorders that are disproportionately caused by repeat expansions (REs) of short tandem repeats (STRs). Genetic diagnosis for RE disorders such as ataxias are difficult as the current gold standard for diagnosis is repeat-primed PCR assays or Southern blots, neither of which are scalable nor readily available for all STR loci. In the last five years, significant advances have been made in our ability to detect STRs and REs in short-read sequencing data, especially whole-genome sequencing. Given the increasing reliance of genomics in diagnosis of rare diseases, the use of established RE detection pipelines for RE disorders is now a highly feasible and practical first-step alternative to molecular testing methods. In addition, many new pathogenic REs have been discovered in recent years by utilising WGS data. Collectively, genomes are an important resource/platform for further advancements in both the discovery and diagnosis of REs that cause ataxia and will lead to much needed improvement in diagnostic rates for patients with hereditary ataxia.
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Affiliation(s)
- Haloom Rafehi
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Mark F Bennett
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, VIC, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
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Wright GEB, Collins JA, Kay C, McDonald C, Dolzhenko E, Xia Q, Bečanović K, Drögemöller BI, Semaka A, Nguyen CM, Trost B, Richards F, Bijlsma EK, Squitieri F, Ross CJD, Scherer SW, Eberle MA, Yuen RKC, Hayden MR. Length of Uninterrupted CAG, Independent of Polyglutamine Size, Results in Increased Somatic Instability, Hastening Onset of Huntington Disease. Am J Hum Genet 2019; 104:1116-1126. [PMID: 31104771 DOI: 10.1016/j.ajhg.2019.04.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/10/2019] [Indexed: 01/28/2023] Open
Abstract
Huntington disease (HD) is caused by a CAG repeat expansion in the huntingtin (HTT) gene. Although the length of this repeat is inversely correlated with age of onset (AOO), it does not fully explain the variability in AOO. We assessed the sequence downstream of the CAG repeat in HTT [reference: (CAG)n-CAA-CAG], since variants within this region have been previously described, but no study of AOO has been performed. These analyses identified a variant that results in complete loss of interrupting (LOI) adenine nucleotides in this region [(CAG)n-CAG-CAG]. Analysis of multiple HD pedigrees showed that this LOI variant is associated with dramatically earlier AOO (average of 25 years) despite the same polyglutamine length as in individuals with the interrupting penultimate CAA codon. This LOI allele is particularly frequent in persons with reduced penetrance alleles who manifest with HD and increases the likelihood of presenting clinically with HD with a CAG of 36-39 repeats. Further, we show that the LOI variant is associated with increased somatic repeat instability, highlighting this as a significant driver of this effect. These findings indicate that the number of uninterrupted CAG repeats, which is lengthened by the LOI, is the most significant contributor to AOO of HD and is more significant than polyglutamine length, which is not altered in these individuals. In addition, we identified another variant in this region, where the CAA-CAG sequence is duplicated, which was associated with later AOO. Identification of these cis-acting modifiers have potentially important implications for genetic counselling in HD-affected families.
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Affiliation(s)
- Galen E B Wright
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Jennifer A Collins
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Chris Kay
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Cassandra McDonald
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | | | - Qingwen Xia
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Kristina Bečanović
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Britt I Drögemöller
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Alicia Semaka
- Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - Charlotte M Nguyen
- The Hospital For Sick Children, The Centre for Applied Genomics, Genetics and Genome Biology, Toronto, ON M5G 0A4, Canada; University of Toronto, Department of Molecular Genetics, Toronto, ON M5G 0A4, Canada
| | - Brett Trost
- The Hospital For Sick Children, The Centre for Applied Genomics, Genetics and Genome Biology, Toronto, ON M5G 0A4, Canada
| | - Fiona Richards
- Department of Clinical Genetics, Children's Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Emilia K Bijlsma
- Department of Clinical Genetics, Leiden University Medical Center, Leiden 2333, the Netherlands
| | - Ferdinando Squitieri
- Huntington and Rare Diseases Unit, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo 71013, Italy
| | - Colin J D Ross
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Stephen W Scherer
- The Hospital For Sick Children, The Centre for Applied Genomics, Genetics and Genome Biology, Toronto, ON M5G 0A4, Canada; University of Toronto, Department of Molecular Genetics, Toronto, ON M5G 0A4, Canada; McLaughlin Centre, University of Toronto, Toronto, ON M5G 0A4, Canada
| | | | - Ryan K C Yuen
- The Hospital For Sick Children, The Centre for Applied Genomics, Genetics and Genome Biology, Toronto, ON M5G 0A4, Canada; University of Toronto, Department of Molecular Genetics, Toronto, ON M5G 0A4, Canada
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.
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Wu C, Cai Q, You H, Zhou X, Chen D, Mo G, Li X. Co-occurrence of ATXN3 and ATXN2 repeat expansions in Chinese ataxia patients with slow saccades. Mol Genet Genomic Med 2019; 7:e663. [PMID: 30920184 PMCID: PMC6565543 DOI: 10.1002/mgg3.663] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/27/2019] [Accepted: 03/06/2019] [Indexed: 12/26/2022] Open
Abstract
Background The presence of more than one polyQ‐related gene within a single individual is a rare incidence, which may provide the potential opportunity to study the combined effects of these spinocerebellar ataxia (SCA) genes. Methods We retrospectively analyzed genetic data from 112 SCA3 probands and found Patient 1 harbored expanded ATXN2 allele (33 repeats) and intermediate TBP allele (41 repeats), and Patient 2 with intermediate ATXN2 allele (32 repeats). Detailed clinical and oculomotor performances were investigated. The age at onset and oculomotor parameters of both patients were compared with matched pure SCA3 groups controlling either disease severity or CAG repeats. Results Most of the clinical phenotypes and oculomotor characteristics of these two patients were common to typical SCA3 patients. Compared to pure SCA3 groups controlling disease severity, mild reduced horizontal saccade velocity could be detected in both patients. However, mild expansions of the ATXN2 allele seemed to have no influence on the age at onset of Patient 1 but might have a mild impact on Patient 2. Conclusion Our study provides supporting evidence that mild expansions of ATXN2 may have modifying effects on SCA3 phenotype. Larger control series and longitudinal data are warranted to confirm our results.
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Affiliation(s)
- Chao Wu
- Department of Neurology, National Key Clinical Department and Key Discipline of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Qiong Cai
- Department of Neurology, National Key Clinical Department and Key Discipline of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Huajing You
- Department of Neurology, National Key Clinical Department and Key Discipline of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xiangxue Zhou
- Department of Neurology, The East Area of the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Dingbang Chen
- Department of Neurology, National Key Clinical Department and Key Discipline of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Guiling Mo
- Guangzhou KingMed Center for Clinical Laboratory Co. Ltd, Guangzhou, Guangdong, China
| | - Xunhua Li
- Department of Neurology, National Key Clinical Department and Key Discipline of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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Vishwakarma P, Muthuswamy S, Agarwal S. Current molecular insight to reveal the dynamics of CAG repeating units in spinocerebellar ataxia. Intractable Rare Dis Res 2018; 7:79-86. [PMID: 29862148 PMCID: PMC5982628 DOI: 10.5582/irdr.2018.01039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Spinocerebellar ataxia (SCA) is a heterogeneous genetic disorder with overlapping clinical phenotypes arising from the degeneration of purkinje cells and other regions of the brain. There are approximately 36 different subtypes of SCA, but SCA 1, 2, 3, 6 and 7 are most prevalent in the Indian population. Many findings suggested that cerebellar Purkinje cells region may be a uniquely vulnerable neuronal cell type, and more susceptible to a wider variety of genetic or cellular problems than other neuron types. In this review we emphasized mainly five common subtypes of SCA (1, 2, 3, 6 and 7) their pathophysiology, therapeutics, drugs studies and the technical challenges in the field of molecular genetic diagnosis.
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Affiliation(s)
- Priyanka Vishwakarma
- Department of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Srinivasan Muthuswamy
- Department of Life Science, National Institute of Technology, Rourkela, Odisha, India
| | - Sarita Agarwal
- Department of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
- Address correspondence to:Dr. Sarita Agarwal, Department of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India. E-mail:
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8
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Tan RH, Kril JJ, McGinley C, Hassani M, Masuda-Suzukake M, Hasegawa M, Mito R, Kiernan MC, Halliday GM. Cerebellar neuronal loss in amyotrophic lateral sclerosis cases with ATXN2 intermediate repeat expansions. Ann Neurol 2016; 79:295-305. [DOI: 10.1002/ana.24565] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 11/03/2015] [Accepted: 11/15/2015] [Indexed: 02/05/2023]
Affiliation(s)
- Rachel H Tan
- Neuroscience Research Australia; Sydney Australia
- School of Medical Sciences; University of New South Wales; Sydney Australia
| | - Jillian J Kril
- Discipline of Pathology, Sydney Medical School; The University of Sydney; Sydney Australia
| | - Ciara McGinley
- Discipline of Pathology, Sydney Medical School; The University of Sydney; Sydney Australia
| | | | - Masami Masuda-Suzukake
- Department of Neuropathology and Cell Biology; Tokyo Metropolitan Institute of Medical Science; Tokyo Japan
| | - Masato Hasegawa
- Department of Neuropathology and Cell Biology; Tokyo Metropolitan Institute of Medical Science; Tokyo Japan
| | - Remika Mito
- Discipline of Pathology, Sydney Medical School; The University of Sydney; Sydney Australia
| | - Matthew C Kiernan
- Brain and Mind Center, Sydney Medical School; The University of Sydney; Sydney Australia
| | - Glenda M Halliday
- Neuroscience Research Australia; Sydney Australia
- School of Medical Sciences; University of New South Wales; Sydney Australia
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9
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Parkinsonism in spinocerebellar ataxia. BIOMED RESEARCH INTERNATIONAL 2015; 2015:125273. [PMID: 25866756 PMCID: PMC4383270 DOI: 10.1155/2015/125273] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/29/2014] [Accepted: 10/13/2014] [Indexed: 11/17/2022]
Abstract
Spinocerebellar ataxia (SCA) presents heterogeneous clinical phenotypes, and parkinsonism is reported in diverse SCA subtypes. Both levodopa responsive Parkinson disease (PD) like phenotype and atypical parkinsonism have been described especially in SCA2, SCA3, and SCA17 with geographic differences in prevalence. SCA2 is the most frequently reported subtype of SCA related to parkinsonism worldwide. Parkinsonism in SCA2 has unique genetic characteristics, such as low number of expansions and interrupted structures, which may explain the sporadic cases with low penetrance. Parkinsonism in SCA17 is more remarkable in Asian populations especially in Korea. In addition, an unclear cutoff of the pathologic range is the key issue in SCA17 related parkinsonism. SCA3 is more common in western cohorts. SCA6 and SCA8 have also been reported with a PD-like phenotype. Herein, we reviewed the epidemiologic, clinical, genetic, and pathologic features of parkinsonism in SCAs.
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Subramony S, Moscovich M, Ashizawa T. Genetics and Clinical Features of Inherited Ataxias. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00062-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Lu HP, Gan SR, Chen S, Li HF, Liu ZJ, Ni W, Wang N, Wu ZY. Intermediate-length polyglutamine in ATXN2 is a possible risk factor among Eastern Chinese patients with amyotrophic lateral sclerosis. Neurobiol Aging 2014; 36:1603.e11-4. [PMID: 25457026 DOI: 10.1016/j.neurobiolaging.2014.10.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 10/07/2014] [Accepted: 10/12/2014] [Indexed: 10/24/2022]
Abstract
An effective treatment for amyotrophic lateral sclerosis (ALS) has not yet been found because the pathogenesis of this fatal disease is not well understood. A number of previous studies demonstrated that intermediate-length polyglutamine repeats within the ataxin-2 gene (ATXN2) might be a risk factor among patients with ALS in Western countries. Here, we aim to determine whether this sequence is a risk factor in Eastern Chinese ALS patients. Therefore, 379 unrelated sporadic ALS patients, 15 unrelated familial ALS patients, and 900 neurologically normal controls were studied. The ATXN2 CAG repeats were amplified using polymerase chain reaction. The products were separated on an 8% polyacrylamide gel and confirmed using Sanger sequencing. The results were evaluated using SPSS 17.0. We found that ATXN2 intermediate-length polyglutamine expansions greater than 24 and 27 repeats were associated with sporadic ALS. Our finding supports the hypothesis that ATXN2 plays an important role in the pathogenesis of ALS.
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Affiliation(s)
- Hai-Peng Lu
- Department of Neurology and Institute of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China; Department of Neurology, Jinhua Hospital, Zhejiang University, Jinhua, China
| | - Shi-Rui Gan
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Sheng Chen
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Hong-Fu Li
- Department of Neurology and Institute of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Zhi-Jun Liu
- Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Wang Ni
- Department of Neurology and Institute of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China; Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Ning Wang
- Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Zhi-Ying Wu
- Department of Neurology and Institute of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China.
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Wang MD, Gomes J, Cashman NR, Little J, Krewski D. Intermediate CAG repeat expansion in the ATXN2 gene is a unique genetic risk factor for ALS--a systematic review and meta-analysis of observational studies. PLoS One 2014; 9:e105534. [PMID: 25148523 PMCID: PMC4141758 DOI: 10.1371/journal.pone.0105534] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/24/2014] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a rare degenerative condition of the motor neurons. Over 10% of ALS cases are linked to monogenic mutations, with the remainder thought to be due to other risk factors, including environmental factors, genetic polymorphisms, and possibly gene-environmental interactions. We examined the association between ALS and an intermediate CAG repeat expansion in the ATXN2 gene using a meta-analytic approach. Observational studies were searched with relevant disease and gene terms from MEDLINE, EMBASE, and PsycINFO from January 2010 through to January 2014. All identified articles were screened using disease terms, gene terms, population information, and CAG repeat information according to PRISMA guidelines. The final list of 17 articles was further evaluated based on the study location, time period, and authors to exclude multiple usage of the same study populations: 13 relevant articles were retained for this study. The range 30-33 CAG repeats in the ATXN2 gene was most strongly associated with ALS. The meta-analysis revealed that the presence of an intermediate CAG repeat (30-33) in the ATXN2 gene was associated with an increased risk of ALS [odds ratio (OR) = 4.44, 95%CI: 2.91-6.76)] in Caucasian ALS patients. There was no significant difference in the association of this CAG intermediate repeat expansion in the ATXN2 gene between familial ALS cases (OR = 3.59, 1.58-8.17) and sporadic ALS cases (OR = 3.16, 1.88-5.32). These results indicate that the presence of intermediate CAG repeat expansion in the ATXN2 gene is a specific genetic risk factor for ALS, unlike monogenic mutations with an autosomal dominant transmission mode, which cause a more severe phenotype of ALS, with a higher prevalence in familial ALS.
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Affiliation(s)
- Ming-Dong Wang
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - James Gomes
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Neil R. Cashman
- Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Julian Little
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Daniel Krewski
- Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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Taking a risk: a therapeutic focus on ataxin-2 in amyotrophic lateral sclerosis? Trends Mol Med 2014; 20:25-35. [DOI: 10.1016/j.molmed.2013.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/03/2013] [Accepted: 09/17/2013] [Indexed: 12/12/2022]
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Abstract
Pathogenic CAG repeat expansion in the ataxin-2 gene (ATXN2) is the genetic cause of spinocerebellar ataxia type 2 (SCA2). Recently, it has been associated with Parkinsonism and increased genetic risk for amyotrophic lateral sclerosis (ALS). Here we report the association of de novo mutations in ATXN2 with autosomal dominant ALS. These findings support our previous conjectures based on population studies on the role of large normal ATXN2 alleles as the source for new mutations being involved in neurodegenerative pathologies associated with CAG expansions. The de novo mutations expanded from ALS/SCA2 non-risk alleles as proven by meta-analysis method. The ALS risk was associated with SCA2 alleles as well as with intermediate CAG lengths in the ATXN2. Higher risk for ALS was associated with pathogenic CAG repeat as revealed by meta-analysis.
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Gellera C, Ticozzi N, Pensato V, Nanetti L, Castucci A, Castellotti B, Lauria G, Taroni F, Silani V, Mariotti C. ATAXIN2 CAG-repeat length in Italian patients with amyotrophic lateral sclerosis: risk factor or variant phenotype? Implication for genetic testing and counseling. Neurobiol Aging 2012; 33:1847.e15-21. [PMID: 22425256 DOI: 10.1016/j.neurobiolaging.2012.02.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 02/02/2012] [Accepted: 02/04/2012] [Indexed: 11/26/2022]
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Affiliation(s)
- Georg W J Auburger
- Section Molecular Neurogenetics, Department of Neurology, Johann Wolfgang Goeche University Medical School, Frankfurt/Main, Germany.
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Ross OA, Rutherford NJ, Baker M, Soto-Ortolaza AI, Carrasquillo MM, DeJesus-Hernandez M, Adamson J, Li M, Volkening K, Finger E, Seeley WW, Hatanpaa KJ, Lomen-Hoerth C, Kertesz A, Bigio EH, Lippa C, Woodruff BK, Knopman DS, White CL, Van Gerpen JA, Meschia JF, Mackenzie IR, Boylan K, Boeve BF, Miller BL, Strong MJ, Uitti RJ, Younkin SG, Graff-Radford NR, Petersen RC, Wszolek ZK, Dickson DW, Rademakers R. Ataxin-2 repeat-length variation and neurodegeneration. Hum Mol Genet 2011; 20:3207-12. [PMID: 21610160 DOI: 10.1093/hmg/ddr227] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Expanded glutamine repeats of the ataxin-2 (ATXN2) protein cause spinocerebellar ataxia type 2 (SCA2), a rare neurodegenerative disorder. More recent studies have suggested that expanded ATXN2 repeats are a genetic risk factor for amyotrophic lateral sclerosis (ALS) via an RNA-dependent interaction with TDP-43. Given the phenotypic diversity observed in SCA2 patients, we set out to determine the polymorphic nature of the ATXN2 repeat length across a spectrum of neurodegenerative disorders. In this study, we genotyped the ATXN2 repeat in 3919 neurodegenerative disease patients and 4877 healthy controls and performed logistic regression analysis to determine the association of repeat length with the risk of disease. We confirmed the presence of a significantly higher number of expanded ATXN2 repeat carriers in ALS patients compared with healthy controls (OR = 5.57; P= 0.001; repeat length >30 units). Furthermore, we observed significant association of expanded ATXN2 repeats with the development of progressive supranuclear palsy (OR = 5.83; P= 0.004; repeat length >30 units). Although expanded repeat carriers were also identified in frontotemporal lobar degeneration, Alzheimer's and Parkinson's disease patients, these were not significantly more frequent than in controls. Of note, our study identified a number of healthy control individuals who harbor expanded repeat alleles (31-33 units), which suggests caution should be taken when attributing specific disease phenotypes to these repeat lengths. In conclusion, our findings confirm the role of ATXN2 as an important risk factor for ALS and support the hypothesis that expanded ATXN2 repeats may predispose to other neurodegenerative diseases, including progressive supranuclear palsy.
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Affiliation(s)
- Owen A Ross
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
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ATXN-2 CAG repeat expansions are interrupted in ALS patients. Hum Genet 2011; 130:575-80. [PMID: 21537950 DOI: 10.1007/s00439-011-1000-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 04/21/2011] [Indexed: 10/18/2022]
Abstract
It has recently been suggested that short expansions of CAG repeat in the gene ATXN-2 causing SCA2 (spinocerebellar ataxia type 2) are associated with an increased risk of amyotrophic lateral sclerosis (ALS) in the populations of the USA and northern Europe. In this study, we investigated the role of ATXN-2 in Italian patients clinically diagnosed with ALS and characterized the molecular structure of ATXN-2 expansions. We assessed the size of the CAG repeat in ATXN-2 exon 1 in 232 Italian ALS patients and 395 matched controls. ATXN-2 expanded alleles containing > 30 repeats have been observed in seven sporadic ALS patients (3.0%), while being absent in the controls (p = 0.00089). Four out of the seven patients had an ATXN-2 allele in the intermediate-fully pathological range: one with 32 repeats, 2 with 33 repeats and 1 with 37 repeats, accounting for 1.7% of the ALS cohort. Sequencing of expanded (> 32) alleles showed that they were all interrupted with at least one CAA triplet. ATXN-2 alleles with the same length and structure have been reported in SCA2 patients with parkinsonism or in familial and sporadic Parkinson. Conversely, the phenotype of the present patients was typically ALS with no signs or symptoms of ataxia or parkinsonism. In conclusion, the findings of ATXN-2 expansions in pure ALS cases suggest that ALS may be a third phenotype (alongside ataxia/parkinsonism and pure Parkinson) associated with ATXN-2 interrupted alleles.
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19
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Yu Z, Zhu Y, Chen-Plotkin AS, Clay-Falcone D, McCluskey L, Elman L, Kalb RG, Trojanowski JQ, Lee VMY, Van Deerlin VM, Gitler AD, Bonini NM. PolyQ repeat expansions in ATXN2 associated with ALS are CAA interrupted repeats. PLoS One 2011; 6:e17951. [PMID: 21479228 PMCID: PMC3066214 DOI: 10.1371/journal.pone.0017951] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 02/16/2011] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressive disease leading to paralysis and death. Recently, intermediate length polyglutamine (polyQ) repeats of 27-33 in ATAXIN-2 (ATXN2), encoding the ATXN2 protein, were found to increase risk for ALS. In ATXN2, polyQ expansions of ≥ 34, which are pure CAG repeat expansions, cause spinocerebellar ataxia type 2. However, similar length expansions that are interrupted with other codons, can present atypically with parkinsonism, suggesting that configuration of the repeat sequence plays an important role in disease manifestation in ATXN2 polyQ expansion diseases. Here we determined whether the expansions in ATXN2 associated with ALS were pure or interrupted CAG repeats, and defined single nucleotide polymorphisms (SNPs) rs695871 and rs695872 in exon 1 of the gene, to assess haplotype association. We found that the expanded repeat alleles of 40 ALS patients and 9 long-repeat length controls were all interrupted, bearing 1-3 CAA codons within the CAG repeat. 21/21 expanded ALS chromosomes with 3CAA interruptions arose from one haplotype (GT), while 18/19 expanded ALS chromosomes with <3CAA interruptions arose from a different haplotype (CC). Moreover, age of disease onset was significantly earlier in patients bearing 3 interruptions vs fewer, and was distinct between haplotypes. These results indicate that CAG repeat expansions in ATXN2 associated with ALS are uniformly interrupted repeats and that the nature of the repeat sequence and haplotype, as well as length of polyQ repeat, may play a role in the neurological effect conferred by expansions in ATXN2.
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Affiliation(s)
- Zhenming Yu
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Yongqing Zhu
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alice S. Chen-Plotkin
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Dana Clay-Falcone
- Center for Neurodegenerative Disease Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Leo McCluskey
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Lauren Elman
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Robert G. Kalb
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - John Q. Trojanowski
- Center for Neurodegenerative Disease Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Virginia M.-Y. Lee
- Center for Neurodegenerative Disease Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Vivianna M. Van Deerlin
- Center for Neurodegenerative Disease Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Aaron D. Gitler
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Nancy M. Bonini
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Howard Hughes Medical Institute, Philadelphia, Pennsylvania, United States of America
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20
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Abstract
The spinocerebellar ataxias (SCA) are a large group of inherited disorders affecting the cerebellum and its afferent and efferent pathways. Their hallmark symptom is slowly progressive, symmetrical, midline, and appendicular ataxia. Some may also have associated hyperkinetic movements (chorea, dystonia, myoclonus, postural/action tremor, restless legs, rubral tremor, tics), which may aid in differential diagnosis and provide treatable targets to improve performance and quality of life in these progressive, incurable conditions. The typical dominant ataxias with associated hyperkinetic movements are SCA1-3, 6-8, 12, 14, 15, 17, 19-21, and 27. The common recessive ataxias with associated hyperkinetic movements are ataxia telangiectasia and Friedreich's ataxia. Fragile X tremor-ataxia syndrome (FXTAS) and multiple-system atrophy (a sporadic ataxia which is felt to have a genetic substrate) also have hyperkinetic features. A careful work-up should be done in all apparently sporadic cases, to rule out acquired causes of ataxia, some of which can cause hyperkinetic movements in addition to ataxia. Some testing should be done even in individuals with a confirmed genetic cause, as the presence of a secondary factor (nutritional deficiency, thyroid dysfunction) can contribute to the phenotype.
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Affiliation(s)
- Susan L Perlman
- David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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21
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Ramos EM, Martins S, Alonso I, Emmel VE, Saraiva-Pereira ML, Jardim LB, Coutinho P, Sequeiros J, Silveira I. Common origin of pure and interrupted repeat expansions in spinocerebellar ataxia type 2 (SCA2). Am J Med Genet B Neuropsychiatr Genet 2010; 153B:524-531. [PMID: 19676102 DOI: 10.1002/ajmg.b.31013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease characterized by gait and limb ataxia. This disease is caused by the expansion of a (CAG)(n) located in the ATXN2, that encodes a polyglutamine tract of more than 34 repeats. Lately, alleles with 32-33 CAGs have been associated to late-onset disease cases. Repeat interruptions by CAA triplets are common in normal alleles, while expanded alleles usually contain a pure repeat tract. To investigate the mutational origin and the instability associated to the ATXN2 repeat, we performed an extensive haplotype study and sequencing of the CAG/CAA repeat, in a cohort of families of different geographic origins and phenotypes. Our results showed (1) CAA interruptions also in expanded ATXN2 alleles; (2) that pathological CAA interrupted alleles shared an ancestral haplotype with pure expanded alleles; and (3) higher genetic diversity in European SCA2 families, suggesting an older European ancestry of SCA2. In conclusion, we found instability towards expansion in interrupted ATXN2 alleles and a shared ancestral ATXN2 haplotype for pure and interrupted expanded alleles; this finding has strong implications in mutation diagnosis and counseling. Our results indicate that interrupted alleles, below the pathological threshold, may be a reservoir of mutable alleles, prone to expansion in subsequent generations, leading to full disease mutation.
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Affiliation(s)
- Eliana Marisa Ramos
- UnIGENe, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Sandra Martins
- UnIGENe, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,IPATIMUP-Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal
| | - Isabel Alonso
- UnIGENe, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | | | | | | | - Paula Coutinho
- UnIGENe, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Hospital São Sebastião, Feira, Portugal
| | - Jorge Sequeiros
- UnIGENe, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Isabel Silveira
- UnIGENe, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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22
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Socal M, Emmel V, Rieder C, Hilbig A, Saraiva-Pereira M, Jardim L. Intrafamilial variability of Parkinson phenotype in SCAs: Novel cases due to SCA2 and SCA3 expansions. Parkinsonism Relat Disord 2009; 15:374-8. [DOI: 10.1016/j.parkreldis.2008.09.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 09/17/2008] [Accepted: 09/18/2008] [Indexed: 10/21/2022]
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23
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Gao R, Matsuura T, Coolbaugh M, Zühlke C, Nakamura K, Rasmussen A, Siciliano MJ, Ashizawa T, Lin X. Instability of expanded CAG/CAA repeats in spinocerebellar ataxia type 17. Eur J Hum Genet 2007; 16:215-22. [PMID: 18043721 DOI: 10.1038/sj.ejhg.5201954] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Trinucleotide repeat expansions are dynamic mutations causing many neurological disorders, and their instability is influenced by multiple factors. Repeat configuration seems particularly important, and pure repeats are thought to be more unstable than interrupted repeats. But direct evidence is still lacking. Here, we presented strong support for this hypothesis from our studies on spinocerebellar ataxia type 17 (SCA17). SCA17 is a typical polyglutamine disease caused by CAG repeat expansion in TBP (TATA binding protein), and is unique in that the pure expanded polyglutamine tract is coded by either a simple configuration with long stretches of pure CAGs or a complex configuration containing CAA interruptions. By small pool PCR (SP-PCR) analysis of blood DNA from SCA17 patients of distinct racial backgrounds, we quantitatively assessed the instability of these two types of expanded alleles coding similar length of polyglutamine expansion. Mutation frequency in patients harboring pure CAG repeats is 2-3 folds of those with CAA interruptions. Interestingly, the pure CAG repeats showed both expansion and deletion while the interrupted repeats exhibited mostly deletion at a significantly lower frequency. These data strongly suggest that repeat configuration is a critical determinant for instability, and CAA interruptions might serve as a limiting element for further expansion of CAG repeats in SCA17 locus, suggesting a molecular basis for lack of anticipation in SCA17 families with interrupted CAG expansion.
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Affiliation(s)
- Rui Gao
- Department of Neurology, The University of Texas Medical Branch, Galveston, TX 77555-0653, USA
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24
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Sobczak K, Krzyzosiak WJ. CAG repeats containing CAA interruptions form branched hairpin structures in spinocerebellar ataxia type 2 transcripts. J Biol Chem 2004; 280:3898-910. [PMID: 15533937 DOI: 10.1074/jbc.m409984200] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2), one of the hereditary human neurodegenerative disorders, is caused by the expansion of the CAG tandem repeats in the translated sequence of the SCA2 gene. In a normal population the CAG repeat is polymorphic not only in length but also in the number and localization of its CAA interruptions. The aim of this study was to determine the structure of the repeat region in the normal and mutant SCA2 transcripts and to reveal the structural basis of its normal function and dysfunction. We show here that the properties of the CAA interruptions are major determinants of the CAG repeat folding in the normal SCA2 transcripts. We also show that the uninterrupted repeats in mutant transcripts form slippery hairpins, whose length is further reduced by the base pairing of the repeat portion with a specific flanking sequence. The structural organization of the repeat interruption systems present in other human transcripts, such as SCA1, TBP, FOXP2, and MAML2, are also discussed.
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Affiliation(s)
- Krzysztof Sobczak
- Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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25
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Furtado S, Payami H, Lockhart PJ, Hanson M, Nutt JG, Singleton AA, Singleton A, Bower J, Utti RJ, Bird TD, de la Fuente-Fernandez R, Tsuboi Y, Klimek ML, Suchowersky O, Hardy J, Calne DB, Wszolek ZK, Farrer M, Gwinn-Hardy K, Stoessl AJ. Profile of families with parkinsonism-predominant spinocerebellar ataxia type 2 (SCA2). Mov Disord 2004; 19:622-9. [PMID: 15197699 DOI: 10.1002/mds.20074] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) has been recognized recently as an uncommon cause of parkinsonism, an alternate presentation to the typical cerebellar disorder. This research review summarizes the existing literature on parkinsonism-predominant presentation SCA2 and presents new clinical cases of patients with this condition. Various phenotypes are noted in this subtype of SCA2, including parkinsonism indistinguishable from idiopathic Parkinson's disease (PD), parkinsonism plus ataxia, motor neuron disease, and postural tremor. In several kindreds with multiple affected family members, the SCA2 expansion segregated with disease; in addition, several single cases of parkinsonism with and without a family history are also described. The number of repeats in symptomatic patients ranged from 33 to 43. Interruption of the CAG repeat with CAA, CGG, or CCG was found in some individuals, possibly stabilizing the repeat structure and accounting for the relative stability of the repeat size across generations in some families; allele length is not necessarily indicative of trinucleotide repeat architecture. Positron emission tomography scanning in one family showed reduced fluorodopa uptake and normal to increased raclopride binding with a rostrocaudal gradient similar to that found in idiopathic PD. This review emphasizes the importance of testing for SCA2 in patients with parkinsonism and a family history of neurodegenerative disorders. Testing for SCA2 is also important in studies of inherited parkinsonism.
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Affiliation(s)
- Sarah Furtado
- Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada.
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