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Cagnoli C, Brussino A, Mancini C, Ferrone M, Orsi L, Salmin P, Pappi P, Giorgio E, Pozzi E, Cavalieri S, Di Gregorio E, Ferrero M, Filla A, De Michele G, Gellera C, Mariotti C, Nethisinghe S, Giunti P, Stevanin G, Brusco A. Spinocerebellar Ataxia Tethering PCR: A Rapid Genetic Test for the Diagnosis of Spinocerebellar Ataxia Types 1, 2, 3, 6, and 7 by PCR and Capillary Electrophoresis. J Mol Diagn 2018; 20:289-297. [PMID: 29462666 DOI: 10.1016/j.jmoldx.2017.12.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 11/17/2017] [Accepted: 12/19/2017] [Indexed: 12/14/2022] Open
Abstract
Spinocerebellar ataxia (SCA) types 1, 2, 3, 6, and 7, associated with a (CAG)n repeat expansion in coding sequences, are the most prevalent autosomal dominant ataxias worldwide (approximately 60% of the cases). In addition, the phenotype of SCA2 expansions has been now extended to Parkinson disease and amyotrophic lateral sclerosis. Their diagnosis is currently based on a PCR to identify small expanded alleles, followed by a second-level test whenever a false normal homozygous or a CAT interruption in SCA1 needs to be verified. Next-generation sequencing still does not allow efficient detection of these repeats. Here, we show the efficacy of a novel, rapid, and cost-effective method to identify and size pathogenic expansions in SCA1, 2, 3, 6, and 7 and recognize large alleles or interruptions without a second-level test. Twenty-five healthy controls and 33 expansion carriers were analyzed: alleles migrated consistently in different PCRs and capillary runs, and homozygous individuals were always distinguishable from heterozygous carriers of both common and large (>100 repeats) pathogenic CAG expansions. Repeat number could be calculated counting the number of peaks, except for the largest SCA2 and SCA7 alleles. Interruptions in SCA1 were always visible. Overall, our method allows a simpler, cost-effective, and sensibly faster SCA diagnostic protocol compared with the standard technique and to the still unadapted next-generation sequencing.
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Affiliation(s)
- Claudia Cagnoli
- Department of Medical Sciences, University of Turin, Turin, Italy
| | | | - Cecilia Mancini
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Marina Ferrone
- Department of Medical Sciences, University of Turin, Turin, Italy; Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - Laura Orsi
- Department of Laboratory Medicine, and the Neurologic Division I, Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - Paola Salmin
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - Patrizia Pappi
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - Elisa Giorgio
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Elisa Pozzi
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Simona Cavalieri
- Department of Medical Sciences, University of Turin, Turin, Italy
| | | | - Marta Ferrero
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Alessandro Filla
- Department of Neurosciences, Odontostomatological and Reproductive Sciences, University Federico II, Naples, Italy
| | - Giuseppe De Michele
- Department of Neurosciences, Odontostomatological and Reproductive Sciences, University Federico II, Naples, Italy
| | - Cinzia Gellera
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Carlo Besta Neurological Institute, Milan, Italy
| | - Caterina Mariotti
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Carlo Besta Neurological Institute, Milan, Italy
| | - Suran Nethisinghe
- Ataxia Centre, Department of Molecular Neuroscience, Institute of Neurology, University College London, London, United Kingdom
| | - Paola Giunti
- Ataxia Centre, Department of Molecular Neuroscience, Institute of Neurology, University College London, London, United Kingdom
| | - Giovanni Stevanin
- INSERM, U 1127, Institut du Cerveau et de la Moelle epinière, Paris, France; Centre National de la Recherche Scientifique UMR 7225, Paris, France; UMRS 1127, Université Pierre et Marie Curie (Paris 06), Sorbonne Universités, Paris, France; Ecole Pratique des Hautes Etudes, PSL Research University, Paris, France; Centre de Référence de Neurogénétique, Hôpital de la Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, Paris, France
| | - Alfredo Brusco
- Department of Medical Sciences, University of Turin, Turin, Italy; Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Turin, Italy.
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