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Li PP, Moulick R, Feng H, Sun X, Arbez N, Jin J, Marque LO, Hedglen E, Chan HE, Ross CA, Pulst SM, Margolis RL, Woodson S, Rudnicki DD. RNA Toxicity and Perturbation of rRNA Processing in Spinocerebellar Ataxia Type 2. Mov Disord 2021; 36:2519-2529. [PMID: 34390268 PMCID: PMC8884117 DOI: 10.1002/mds.28729] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/03/2021] [Accepted: 07/12/2021] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease caused by expansion of a CAG repeat in Ataxin-2 (ATXN2) gene. The mutant ATXN2 protein with a polyglutamine tract is known to be toxic and contributes to the SCA2 pathogenesis. OBJECTIVE Here, we tested the hypothesis that the mutant ATXN2 transcript with an expanded CAG repeat (expATXN2) is also toxic and contributes to SCA2 pathogenesis. METHODS The toxic effect of expATXN2 transcripts on SK-N-MC neuroblastoma cells and primary mouse cortical neurons was evaluated by caspase 3/7 activity and nuclear condensation assay, respectively. RNA immunoprecipitation assay was performed to identify RNA binding proteins (RBPs) that bind to expATXN2 RNA. Quantitative PCR was used to examine if ribosomal RNA (rRNA) processing is disrupted in SCA2 and Huntington's disease (HD) human brain tissue. RESULTS expATXN2 RNA induces neuronal cell death, and aberrantly interacts with RBPs involved in RNA metabolism. One of the RBPs, transducin β-like protein 3 (TBL3), involved in rRNA processing, binds to both expATXN2 and expanded huntingtin (expHTT) RNA in vitro. rRNA processing is disrupted in both SCA2 and HD human brain tissue. CONCLUSION These findings provide the first evidence of a contributory role of expATXN2 transcripts in SCA2 pathogenesis, and further support the role of expHTT transcripts in HD pathogenesis. The disruption of rRNA processing, mediated by aberrant interaction of RBPs with expATXN2 and expHTT transcripts, suggest a point of convergence in the pathogeneses of repeat expansion diseases with potential therapeutic implications. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Pan P. Li
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Roumita Moulick
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Hongxuan Feng
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Xin Sun
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Nicolas Arbez
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Jing Jin
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Leonard O. Marque
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Erin Hedglen
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - H.Y. Edwin Chan
- Biochemistry Program, School of Life SciencesThe Chinese University of Hong KongHong KongChina
| | - Christopher A. Ross
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
- Department of NeurologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
- Department of NeuroscienceJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Stefan M. Pulst
- Department of NeurologyUniversity of UtahSalt Lake CityUtahUSA
| | - Russell L. Margolis
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
- Department of NeurologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Sarah Woodson
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Dobrila D. Rudnicki
- Department of Psychiatry and Behavioral Sciences, Division of NeurobiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
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Genetic counseling and testing practices for late-onset neurodegenerative disease: a systematic review. J Neurol 2021; 269:676-692. [PMID: 33649871 PMCID: PMC7920548 DOI: 10.1007/s00415-021-10461-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/10/2021] [Accepted: 02/10/2021] [Indexed: 12/28/2022]
Abstract
Objective To understand contemporary genetic counseling and testing practices for late-onset neurodegenerative diseases (LONDs), and identify whether practices address the internationally accepted goals of genetic counseling: interpretation, counseling, education, and support. Methods Four databases were systematically searched for articles published from 2009 to 2020. Peer-reviewed research articles in English that reported research and clinical genetic counseling and testing practices for LONDs were included. A narrative synthesis was conducted to describe different practices and map genetic counseling activities to the goals. Risk of bias was assessed using the Qualsyst tool. The protocol was registered with PROSPERO (CRD42019121421). Results Sixty-one studies from 68 papers were included. Most papers focused on predictive testing (58/68) and Huntington’s disease (41/68). There was variation between papers in study design, study population, outcomes, interventions, and settings. Although there were commonalities, novel and inconsistent genetic counseling practices were identified. Eighteen papers addressed all four goals of genetic counseling. Conclusion Contemporary genetic counseling and testing practices for LONDs are varied and informed by regional differences and the presence of different health providers. A flexible, multidisciplinary, client- and family-centered care continues to emerge. As genetic testing becomes a routine part of care for patients (and their relatives), health providers must balance their limited time and resources with ensuring clients are safely and effectively counseled, and all four genetic counseling goals are addressed. Areas of further research include diagnostic and reproductive genetic counseling/testing practices, evaluations of novel approaches to care, and the role and use of different health providers in practice. Supplementary Information The online version contains supplementary material available at 10.1007/s00415-021-10461-5.
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Lian M, Zhao M, Phang GP, Soong YT, Yoon CS, Lee CG, Law HY, Chong SS. Rapid Molecular Screen of Spinocerebellar Ataxia Types 1, 2, and 3 by Triplet-Primed PCR and Melting Curve Analysis. J Mol Diagn 2021; 23:565-576. [PMID: 33618058 DOI: 10.1016/j.jmoldx.2021.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/02/2020] [Accepted: 01/12/2021] [Indexed: 11/16/2022] Open
Abstract
The autosomal dominantly inherited spinocerebellar ataxias (SCAs) can be caused by dynamic mutations of short tandem repeats within various genes. Because of the significant clinical overlap among the various SCA types, molecular screening of multiple genetic loci by fluorescent PCR and capillary electrophoresis is necessary to identify the causative repeat expansion. We describe a simple, rapid, and inexpensive strategy to screen for CAG repeat expansion mutations at the ATXN1, ATXN2, and ATXN3 loci using melting curve analysis of triplet-primed PCR products. Plasmid DNAs of known repeat sizes were used to generate threshold melt peak temperatures, which rapidly and effectively distinguish samples carrying an expanded allele from those carrying nonexpanded alleles. Melting curve analysis-positive samples were confirmed by capillary electrophoresis sizing of the triplet-primed PCR products. All three assays achieved 100% sensitivity, with 95% CIs of 67.86% to 100% (SCA1), 74.65% to 100% (SCA2), and 91.58% to 100% (SCA3). The SCA1 assay also achieved 100% specificity (95% CI, 97.52%-100%), whereas the SCA2 and SCA3 assays achieved specificity of 99.46% (95% CI, 96.56%-99.97%) and 99.32% (95% CI, 95.70%-99.96%), respectively. These screening assays provide robust and highly accurate detection of expanded alleles and are amenable to large-scale screening while minimizing the need for capillary electrophoresis sizing for every sample.
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Affiliation(s)
- Mulias Lian
- Khoo Teck Puat-National University Children's Medical Institute, National University Health System, Singapore
| | - Mingjue Zhao
- Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Gui-Ping Phang
- Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Yun-Ting Soong
- Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Chui-Sheun Yoon
- Department of Pediatric Medicine, KK Women's and Children's Hospital, Singapore
| | - Caroline G Lee
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Cancer and Stem Cell Biology Program, Duke-NUS Graduate Medical School, Singapore; Division of Medical Sciences, National Cancer Center Singapore, Singapore
| | - Hai-Yang Law
- Department of Pediatric Medicine, KK Women's and Children's Hospital, Singapore; Pediatrics Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore
| | - Samuel S Chong
- Khoo Teck Puat-National University Children's Medical Institute, National University Health System, Singapore; Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Department of Laboratory Medicine, National University Hospital, Singapore.
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Abstract
The spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of autosomal dominantly inherited progressive disorders, the clinical hallmark of which is loss of balance and coordination accompanied by slurred speech; onset is most often in adult life. Genetically, SCAs are grouped as repeat expansion SCAs, such as SCA3/Machado-Joseph disease (MJD), and rare SCAs that are caused by non-repeat mutations, such as SCA5. Most SCA mutations cause prominent damage to cerebellar Purkinje neurons with consecutive cerebellar atrophy, although Purkinje neurons are only mildly affected in some SCAs. Furthermore, other parts of the nervous system, such as the spinal cord, basal ganglia and pontine nuclei in the brainstem, can be involved. As there is currently no treatment to slow or halt SCAs (many SCAs lead to premature death), the clinical care of patients with SCA focuses on managing the symptoms through physiotherapy, occupational therapy and speech therapy. Intense research has greatly expanded our understanding of the pathobiology of many SCAs, revealing that they occur via interrelated mechanisms (including proteotoxicity, RNA toxicity and ion channel dysfunction), and has led to the identification of new targets for treatment development. However, the development of effective therapies is hampered by the heterogeneity of the SCAs; specific therapeutic approaches may be required for each disease.
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Velázquez-Pérez L, Rodríguez-Diaz JC, Rodríguez-Labrada R, Medrano-Montero J, Aguilera Cruz AB, Reynaldo-Cejas L, Góngora-Marrero M, Estupiñán-Rodríguez A, Vázquez-Mojena Y, Torres-Vega R. Neurorehabilitation Improves the Motor Features in Prodromal SCA2: A Randomized, Controlled Trial. Mov Disord 2019; 34:1060-1068. [PMID: 30958572 DOI: 10.1002/mds.27676] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 02/28/2019] [Accepted: 03/07/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The search for early interventions is a novel approach in spinocerebellar ataxias, but there are few studies supporting this notion. This article aimed to assess the efficacy of neurorehabilitation treatment in prodromal spinocerebellar ataxia type 2. METHODS Thirty spinocerebellar ataxia type 2 preclinical carriers were enrolled in a randomized, controlled trial using neurorehabilitation. The intervention in the treated group was 4 hours per day, 5 days per week for 12 weeks, emphasizing static balance, gait, and limb coordination. The control group did not receive rehabilitation. The primary outcome measure was the time for 5-m tandem gait over the floor. Secondary outcomes included other timed tests with increased motor complexity, as well as the scores of the SARA and the Inventory of Non-ataxia Symptoms. RESULTS The times for 5-m tandem gait over the floor and the mattress were significantly reduced only in the rehabilitated group. Moreover, the times upholding the tandem stance over a mattress and the seesaw were notably increased only in this group. Likewise, the finger-nose and the heel-shin tests were improved in the rehabilitated group alone. The SARA score and the count of nonataxia symptoms were unchanged. CONCLUSIONS This rehabilitation program improves the subtle gait, postural and coordinative deficits in prodromal spinocerebellar ataxia type 2, which provided novel hints about the preservation of motor learning and neural plasticity mechanisms in early disease stages, leading chances for other interventional approaches in this and other spinocerebellar ataxias. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Luis Velázquez-Pérez
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Cuban Academy of Sciences, Havana, Cuba
| | | | - Roberto Rodríguez-Labrada
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Cuban Academy of Sciences, Havana, Cuba.,School of Physical Culture and Sport, University of Holguín, Holguín, Cuba
| | - Jacqueline Medrano-Montero
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,School of Physical Culture and Sport, University of Holguín, Holguín, Cuba
| | | | | | | | | | - Yaimeé Vázquez-Mojena
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Cuban Academy of Sciences, Havana, Cuba.,School of Physical Culture and Sport, University of Holguín, Holguín, Cuba
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Abstract
Many neurogenetic conditions are inherited and therefore diagnosis of a patient will have implications for the patient's relatives and can raise ethical issues. Predictive genetic testing offers asymptomatic relatives the opportunity to determine their risk status for a neurogenetic condition, and professional guidelines emphasize patients' autonomy and informed, voluntary decision making. Beneficence and nonmaleficence both need to be considered when making decisions about disclosure and nondisclosure of genetic information and test results. There can be disclosure concerns and challenges in determining whose autonomy to prioritize when a patient makes a genetic testing decision that can reveal the genetic status of a relative (e.g., testing an adult child when the at-risk parent has not been tested). Ethical issues are prominent when genetic testing for neurogenetic conditions is requested prenatally, on minors, adoptees, adult children at 25% risk, and for individuals with psychiatric issues or cognitive impairment. Neurogenetic conditions can result in cognitive decline which can affect decisional capacity and lead to ethical challenges with decision making, informed consent, and determining the patient's ability to comprehend test results. The ethical implications of genetic testing and emerging issues, including direct-to-consumer genetic testing, disclosure of secondary findings from genomic sequencing, and use of apolipoprotein E testing in clinical and research settings, are also discussed. Resources for information about genetic testing practice guidelines, insurance laws, and directories of genetics clinics are included.
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Affiliation(s)
- Wendy R Uhlmann
- Departments of Internal Medicine and Human Genetics, University of Michigan Medical School, Ann Arbor, MI, United States; Center for Bioethics and Social Sciences in Medicine, University of Michigan Medical School, Ann Arbor, MI, United States.
| | - J Scott Roberts
- Department of Health Behavior and Health Education, University of Michigan School of Public Health, Ann Arbor, MI, United States; Center for Bioethics and Social Sciences in Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
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Velázquez-Pérez LC, Rodríguez-Labrada R, Fernandez-Ruiz J. Spinocerebellar Ataxia Type 2: Clinicogenetic Aspects, Mechanistic Insights, and Management Approaches. Front Neurol 2017; 8:472. [PMID: 28955296 PMCID: PMC5601978 DOI: 10.3389/fneur.2017.00472] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/25/2017] [Indexed: 12/14/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia that occurs as a consequence of abnormal CAG expansions in the ATXN2 gene. Progressive clinical features result from the neurodegeneration of cerebellum and extra-cerebellar structures including the pons, the basal ganglia, and the cerebral cortex. Clinical, electrophysiological, and imaging approaches have been used to characterize the natural history of the disease, allowing its classification into four distinct stages, with special emphasis on the prodromal stage, which is characterized by a plethora of motor and non-motor features. Neuropathological investigations of brain tissue from SCA2 patients reveal a widespread involvement of multiple brain systems, mainly cerebellar and brainstem systems. Recent findings linking ataxin-2 intermediate expansions to other neurodegenerative diseases such as amyotrophic lateral sclerosis have provided insights into the ataxin-2-related toxicity mechanism in neurodegenerative diseases and have raised new ethical challenges to molecular predictive diagnosis of SCA2. No effective neuroprotective therapies are currently available for SCA2 patients, but some therapeutic options such as neurorehabilitation and some emerging neuroprotective drugs have shown palliative benefits.
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Affiliation(s)
- Luis C Velázquez-Pérez
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Medical University of Holguín "Mariana Grajales", Holguín, Cuba
| | - Roberto Rodríguez-Labrada
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Physical Culture School, University of Holguin "Oscar Lucero", Holguín, Cuba
| | - Juan Fernandez-Ruiz
- Department of Physiology, Medicine School, UNAM, Cuernavaca, Mexico.,Psychology School, Universidad Veracruzana, Xalapa, Mexico
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Velázquez-Pérez L, Rodríguez-Labrada R, Laffita-Mesa JM. Prodromal spinocerebellar ataxia type 2: Prospects for early interventions and ethical challenges. Mov Disord 2017; 32:708-718. [DOI: 10.1002/mds.26969] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/24/2017] [Accepted: 01/30/2017] [Indexed: 12/29/2022] Open
Affiliation(s)
| | | | - José Miguel Laffita-Mesa
- Centre for the Research and Rehabilitation of Hereditary Ataxias; Holguín Cuba
- Department of Clinical Neuroscience; Karolinska Universitetssjukhuset; Stockholm Sweden
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