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Blanco R, Pichardo J, Abdullah H. Generalized Hypotonia Revealing Spinal Muscular Atrophy Type 2: The First Case Reported From the Dominican Republic and a Review of the Literature. Cureus 2020; 12:e11464. [PMID: 33329961 PMCID: PMC7733768 DOI: 10.7759/cureus.11464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spinal muscular atrophy (SMA) is a rare, inherited autosomal recessive disease. Histopathological shreds of evidence related to the condition have suggested degenerative changes at the level of the spinal cord and brain stem. Deletions or mutations in the survival motor neuron 1 (SMN1) gene are the underlying cause of this disease. It is characterized by hypotonia, muscular atrophy, areflexia, fasciculations, and flaccid paralysis. It is further classified into five variants, depending upon the patient's age and clinical features. In this report, we present a rare case of SMA type 2 in a one-year-old female infant who presented with generalized hypotonia and axial body weakness. Besides clinical evaluation, her genetic analysis confirmed that she had a deletion of one of the SMN1 genes. Hence, the diagnosis of SMA type 2 was confirmed. Our study aims to emphasize that clinicians must consider this rare entity whenever a patient presents with the signs and symptoms mentioned above. As the most common cause of death in this disease is respiratory depression, an early diagnosis would prevent complications and help in the parents' genetic counseling.
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Affiliation(s)
- Rubén Blanco
- Neurology, Pontificia Universidad Católica Madre y Maestra, Santiago, DOM
| | - Jessie Pichardo
- Medicine, Pontificia Universidad Católica Madre y Maestra, Santiago, DOM
| | - Hassan Abdullah
- Neurology, University of Alabama, Birmingham, USA.,Medicine, Nishtar Medical University, Multan, PAK
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Shorrock HK, Gillingwater TH, Groen EJN. Molecular Mechanisms Underlying Sensory-Motor Circuit Dysfunction in SMA. Front Mol Neurosci 2019; 12:59. [PMID: 30886572 PMCID: PMC6409332 DOI: 10.3389/fnmol.2019.00059] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/15/2019] [Indexed: 12/19/2022] Open
Abstract
Activation of skeletal muscle in response to acetylcholine release from the neuromuscular junction triggered by motor neuron firing forms the basis of all mammalian locomotion. Intricate feedback and control mechanisms, both from within the central nervous system and from sensory organs in the periphery, provide essential inputs that regulate and finetune motor neuron activity. Interestingly, in motor neuron diseases, such as spinal muscular atrophy (SMA), pathological studies in patients have identified alterations in multiple parts of the sensory-motor system. This has stimulated significant research efforts across a range of different animal models of SMA in order to understand these defects and their contribution to disease pathogenesis. Several recent studies have demonstrated that defects in sensory components of the sensory-motor system contribute to dysfunction of motor neurons early in the pathogenic process. In this review, we provide an overview of these findings, with a specific focus on studies that have provided mechanistic insights into the molecular processes that underlie dysfunction of the sensory-motor system in SMA. These findings highlight the role that cell types other than motor neurons play in SMA pathogenesis, and reinforce the need for therapeutic interventions that target and rescue the wide array of defects that occur in SMA.
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Affiliation(s)
- Hannah K Shorrock
- Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,Euan MacDonald Centre for Motor Neurone Disease Research, The University of Edinburgh, Edinburgh, United Kingdom
| | - Thomas H Gillingwater
- Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,Euan MacDonald Centre for Motor Neurone Disease Research, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ewout J N Groen
- Edinburgh Medical School: Biomedical Sciences, The University of Edinburgh, Edinburgh, United Kingdom.,Euan MacDonald Centre for Motor Neurone Disease Research, The University of Edinburgh, Edinburgh, United Kingdom
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Shorrock HK, van der Hoorn D, Boyd PJ, Llavero Hurtado M, Lamont DJ, Wirth B, Sleigh JN, Schiavo G, Wishart TM, Groen EJN, Gillingwater TH. UBA1/GARS-dependent pathways drive sensory-motor connectivity defects in spinal muscular atrophy. Brain 2018; 141:2878-2894. [PMID: 30239612 PMCID: PMC6158753 DOI: 10.1093/brain/awy237] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 07/25/2018] [Indexed: 01/09/2023] Open
Abstract
Deafferentation of motor neurons as a result of defective sensory-motor connectivity is a critical early event in the pathogenesis of spinal muscular atrophy, but the underlying molecular pathways remain unknown. We show that restoration of ubiquitin-like modifier-activating enzyme 1 (UBA1) was sufficient to correct sensory-motor connectivity in the spinal cord of mice with spinal muscular atrophy. Aminoacyl-tRNA synthetases, including GARS, were identified as downstream targets of UBA1. Regulation of GARS by UBA1 occurred via a non-canonical pathway independent of ubiquitylation. Dysregulation of UBA1/GARS pathways in spinal muscular atrophy mice disrupted sensory neuron fate, phenocopying GARS-dependent defects associated with Charcot-Marie-Tooth disease. Sensory neuron fate was corrected following restoration of UBA1 expression and UBA1/GARS pathways in spinal muscular atrophy mice. We conclude that defective sensory motor connectivity in spinal muscular atrophy results from perturbations in a UBA1/GARS pathway that modulates sensory neuron fate, thereby highlighting significant molecular and phenotypic overlap between spinal muscular atrophy and Charcot-Marie-Tooth disease.
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Affiliation(s)
- Hannah K Shorrock
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK,Present address: Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, University of Florida, 2033 Mowry Road, Gainesville, FL 32610, USA
| | - Dinja van der Hoorn
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Penelope J Boyd
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK,Present address: Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, UK
| | - Maica Llavero Hurtado
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK, Roslin Institute, Royal (Dick) School of Veterinary Science, University of Edinburgh, UK
| | | | - Brunhilde Wirth
- Institute of Human Genetics, Center for Molecular Medicine Cologne, Institute for Genetics and Center for Rare Diseases Cologne, University of Cologne, Germany
| | - James N Sleigh
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, UK
| | - Giampietro Schiavo
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, UK, Discoveries Centre for Regenerative and Precision Medicine, University College London Campus, London, UK, UK Dementia Research Institute at UCL, London, UK
| | - Thomas M Wishart
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK, Roslin Institute, Royal (Dick) School of Veterinary Science, University of Edinburgh, UK
| | - Ewout J N Groen
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK,Correspondence may also be addressed to: Ewout J. N. Groen E-mail:
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK,Correspondence to: Thomas H. Gillingwater University of Edinburgh - Biomedical Sciences (Anatomy) Hugh Robson Building George Square Edinburgh, Scotland EH8 9XD, UK E-mail:
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