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Spinal Muscular Atrophy

Disease Pathophysiology Research Report

2026-02-01
Falcon MONDO:0001516 Model: Edison Scientific Literature 30 citations

Disease Pathophysiology Research Report

Target Disease

  • Disease Name: Spinal Muscular Atrophy (5q-SMA)
  • MONDO ID: [not provided]
  • Category: Genetic

Pathophysiology description (narrative)

Spinal muscular atrophy (SMA) is caused by homozygous disruption of SMN1, resulting in reduced survival motor neuron (SMN) protein and a spectrum of downstream defects that converge on selective degeneration of lower motor neurons, neuromuscular junction (NMJ) failure, and systemic, multi-organ abnormalities. SMN is a core component of the SMN–Gemins complex essential for spliceosomal snRNP assembly and mRNA splicing; it also associates with ribosomes and translation-related machinery, and regulates axonal/cytoskeletal dynamics and local translation. Recent work emphasizes additional mechanisms: autophagy–lysosome pathway dysregulation; accumulation of R-loops and DNA damage involving senataxin (SETX); innate immune activation; and non-neuronal contributions from muscle, glia, and mesenchymal progenitors. Importantly, SMN-restorative therapies improve outcomes but do not fully normalize downstream cellular biology, particularly in skeletal muscle and metabolism. (haque2024recentprogressin pages 1-2, glynn2025actincytoskeletondysregulation pages 21-24, shi2025cytoskeletondysfunctionof pages 1-3, torri2024beyondmotorneurons pages 1-2, grandi2024characterizationofsma pages 1-2)

Selected quotes supporting key concepts: - “The underlying cause of Spinal Muscular Atrophy (SMA) is in the reduction of survival motor neuron (SMN) protein levels due to mutations in the SMN1 gene… [SMN] has crucial roles… from ribosome biogenesis to local translation and beyond.” URL: https://doi.org/10.1042/bst20231116 (Biochemical Society Transactions, Feb 2024). (haque2024recentprogressin pages 1-2) - “In addition, low levels of senataxin (loss-of-function) in spinal muscular atrophy result in the accumulation of R-loops causing DNA damage and motor neuron degeneration.” URL: https://doi.org/10.1093/braincomms/fcae239 (Brain Communications, Jul 2024). (shi2025cytoskeletondysfunctionof pages 1-3) - “Despite… SMN-dependent disease-modifying therapies… we observed a consistent loss of oxidative phosphorylation (OXPHOS) machinery of the mitochondria… and a correlation between… denervation and increased fibrosis” in treated SMA type II muscle. URL: https://doi.org/10.1172/jci.insight.180992 (JCI Insight, Sep 2024). (grandi2024characterizationofsma pages 1-2)

1. Core Pathophysiology

2. Key Molecular Players

3. Biological Processes (GO annotations; illustrative)

4. Cellular Components (GO-CC)

5. Disease Progression (sequence of events)

6. Phenotypic Manifestations (HPO; illustrative mapping)

Current applications and real-world implementations

  • Approved SMN-targeted therapies: nusinersen (ASO), risdiplam (small molecule), and onasemnogene abeparvovec (AAV9 gene replacement) have transformed outcomes; earlier treatment (including newborn screening) yields better motor function. (torri2024beyondmotorneurons pages 1-2)
  • Real-world registry outcomes (RESTORE): 168 patients treated with onasemnogene abeparvovec monotherapy (data cutoff May 23, 2022). “All patients maintained/achieved motor milestones.” Adverse events: “48.5% (n=81/167) experienced at least one treatment-emergent adverse event (AE), and 31/167 patients (18.6%) experienced at least one serious AE, of which 8/31 were considered treatment-related.” Infants identified by newborn screening had higher final CHOP INTEND scores than clinically diagnosed infants. URL: https://doi.org/10.3233/jnd-230122 (Journal of Neuromuscular Diseases, Jan 2024). (servais2024realworldoutcomesin pages 1-3)
  • Respiratory outcomes after OA: National real-world cohort of 25 children (23 SMA1, 2 SMA2), median age at OA 6.1 months; ventilation time decreased (14.3→11.1 h/day) and respiratory hospitalizations decreased by 26% in the post-treatment year; two deaths due to respiratory failure; authors conclude OA may improve respiratory outcomes but emphasize confounders and need for standardized long-term management. URL: https://doi.org/10.1007/s00431-024-05886-9 (European Journal of Pediatrics, Dec 2024). (lavie2024respiratoryoutcomesof pages 1-2)
  • 2024 European consensus update on gene therapy: updated guidance on rational use of onasemnogene abeparvovec, including considerations for older/heavier patients and integration with trial and real-world evidence; see EJPN consensus and supplementary material. URL: https://doi.org/10.1016/j.ejpn.2024.06.001 (European Journal of Paediatric Neurology, Jun 2024). (kirschner20242024updateeuropean pages 6-6)

Expert opinions and analysis

Relevant statistics and data from recent studies

Evidence items (with direct quotes, PMIDs/DOIs/URLs where available)

1) SMN roles across translation and ribosomes: “Given the crucial roles of the SMN protein in snRNP biogenesis and its interactions with ribosomes… a decrease in SMN levels… is expected to affect translational control of gene expression.” DOI: 10.1042/bst20231116; URL: https://doi.org/10.1042/bst20231116 (Sharma et al., 2024). (haque2024recentprogressin pages 1-2) 2) R-loops and SETX in SMA: “low levels of senataxin… in spinal muscular atrophy result in the accumulation of R-loops causing DNA damage and motor neuron degeneration.” DOI: 10.1093/braincomms/fcae239; URL: https://doi.org/10.1093/braincomms/fcae239 (Kannan et al., 2024). (shi2025cytoskeletondysfunctionof pages 1-3) 3) Autophagy–lysosome: “propose decreased autophagic flux as the causative agent underlying the autophagic dysregulation observed in these patients.” DOI: 10.3389/fncel.2023.1307636; URL: https://doi.org/10.3389/fncel.2023.1307636 (Rashid & Dimitriadi, 2024). (rosignol2024understandinghowsmn pages 1-4) 4) Muscle OXPHOS deficiency despite SMN-restoration: “we observed a consistent loss of oxidative phosphorylation (OXPHOS) machinery of the mitochondria, a decrease in mitochondrial DNA copy number… [and] increased fibrosis” in treated Type II muscle. DOI: 10.1172/jci.insight.180992; URL: https://doi.org/10.1172/jci.insight.180992 (Grandi et al., 2024). (grandi2024characterizationofsma pages 1-2) 5) Real-world OA outcomes (RESTORE): “All patients maintained/achieved motor milestones. 48.5%… experienced at least one treatment-emergent adverse event… 18.6% experienced at least one serious AE…” DOI: 10.3233/jnd-230122; URL: https://doi.org/10.3233/jnd-230122 (Servais et al., 2024). (servais2024realworldoutcomesin pages 1-3) 6) Real-world respiratory impact after OA: “Ventilation time decreased from 14.3 to 11.1 hours per day, and respiratory hospitalizations decreased by 26%” in the year after treatment. DOI: 10.1007/s00431-024-05886-9; URL: https://doi.org/10.1007/s00431-024-05886-9 (Lavie et al., 2024). (lavie2024respiratoryoutcomesof pages 1-2) 7) Consensus guidance: 2024 European consensus update on the rational use of OA, including older/heavier patients and integration of real-world evidence; see main text and Supplementary Data. DOI: 10.1016/j.ejpn.2024.06.001; URL: https://doi.org/10.1016/j.ejpn.2024.06.001 (Kirschner et al., 2024). (kirschner20242024updateeuropean pages 6-6)

Gene/Protein annotations (HGNC) with ontology mapping

Cell type involvement (CL terms)

Anatomical locations (UBERON)

Chemical entities (CHEBI)

Recent developments (2023–2024 emphasis)

References (with URLs and publication dates)

Notes on limitations and open questions

References

  1. (haque2024recentprogressin pages 1-2): Umme Sabrina Haque and Toshifumi Yokota. Recent progress in gene-targeting therapies for spinal muscular atrophy: promises and challenges. Genes, Jul 2024. URL: https://doi.org/10.3390/genes15080999, doi:10.3390/genes15080999. This article has 24 citations and is from a poor quality or predatory journal.

  2. (glynn2025actincytoskeletondysregulation pages 21-24): A Glynn. Actin cytoskeleton dysregulation in peripheral organs in spinal muscular atrophy (sma). Unknown journal, 2025.

  3. (shi2025cytoskeletondysfunctionof pages 1-3): Tianyu Shi, Zijie Zhou, Taiyang Xiang, Yinxuan Suo, Xiaoyan Shi, Yaoyao Li, Peng Zhang, Jun Dai, and Lei Sheng. Cytoskeleton dysfunction of motor neuron in spinal muscular atrophy. Journal of Neurology, Dec 2025. URL: https://doi.org/10.1007/s00415-024-12724-3, doi:10.1007/s00415-024-12724-3. This article has 11 citations and is from a domain leading peer-reviewed journal.

  4. (torri2024beyondmotorneurons pages 1-2): Francesca Torri, Michelangelo Mancuso, Gabriele Siciliano, and Giulia Ricci. Beyond motor neurons in spinal muscular atrophy: a focus on neuromuscular junction. International Journal of Molecular Sciences, 25:7311, Jul 2024. URL: https://doi.org/10.3390/ijms25137311, doi:10.3390/ijms25137311. This article has 8 citations and is from a poor quality or predatory journal.

  5. (grandi2024characterizationofsma pages 1-2): Fiorella Carla Grandi, Stéphanie Astord, Sonia Pezet, Elèna Gidaja, Sabrina Mazzucchi, Maud Chapart, Stéphane Vasseur, Kamel Mamchaoui, and Piera Smeriglio. Characterization of sma type ii skeletal muscle from treated patients shows oxphos deficiency and denervation. JCI Insight, Sep 2024. URL: https://doi.org/10.1172/jci.insight.180992, doi:10.1172/jci.insight.180992. This article has 8 citations and is from a domain leading peer-reviewed journal.

  6. (rosignol2024understandinghowsmn pages 1-4): PDI Rosignol. Understanding how smn protein regulates the autophagy-lysosome pathway in spinal muscular atrophy. Unknown journal, 2024.

  7. (torres2025dissectingtherolea pages 28-32): P Pacheco Torres. Dissecting the role of oxidative stress in spinal muscular atrophy (sma). Unknown journal, 2025.

  8. (chudakova2024insearchof pages 3-5): Daria Chudakova, Ludmila Kuzenkova, Andrey Fisenko, and Kirill Savostyanov. In search of spinal muscular atrophy disease modifiers. International Journal of Molecular Sciences, 25:11210, Oct 2024. URL: https://doi.org/10.3390/ijms252011210, doi:10.3390/ijms252011210. This article has 6 citations and is from a poor quality or predatory journal.

  9. (lavie2024respiratoryoutcomesof pages 1-2): Moran Lavie, Mika Rochman, Keren Armoni Domany, Inbal Golan Tripto, Moria Be’er, Omri Besor, Liora Sagi, Sharon Aharoni, Mira Ginsberg, Iris Noyman, and Hagit Levine. Respiratory outcomes of onasemnogene abeparvovec treatment for spinal muscular atrophy: national real-world cohort study. European Journal of Pediatrics, Dec 2024. URL: https://doi.org/10.1007/s00431-024-05886-9, doi:10.1007/s00431-024-05886-9. This article has 5 citations and is from a peer-reviewed journal.

  10. (servais2024realworldoutcomesin pages 1-3): Laurent Servais, John W. Day, Darryl C. De Vivo, Janbernd Kirschner, Eugenio Mercuri, Francesco Muntoni, Crystal M. Proud, Perry B. Shieh, Eduardo F. Tizzano, Susana Quijano-Roy, Isabelle Desguerre, Kayoko Saito, Eric Faulkner, Kamal M. Benguerba, Dheeraj Raju, Nicole LaMarca, Rui Sun, Frederick A. Anderson, and Richard S. Finkel. Real-world outcomes in patients with spinal muscular atrophy treated with onasemnogene abeparvovec monotherapy: findings from the restore registry. Journal of Neuromuscular Diseases, 11:425-442, Jan 2024. URL: https://doi.org/10.3233/jnd-230122, doi:10.3233/jnd-230122. This article has 58 citations and is from a peer-reviewed journal.

  11. (kirschner20242024updateeuropean pages 6-6): Janbernd Kirschner, Günther Bernert, Nina Butoianu, Liesbeth De Waele, Aviva Fattal-Valevski, Jana Haberlova, Teresa Moreno, Andrea Katharina Klein, Anna Kostera-Pruszczyk, Eugenio Mercuri, Susana Quijano-Roy, Thomas Sejersen, Eduardo F Tizzano, W Ludo van der Pol, Sean Wallace, Dimitrios Zafeiriou, Andreas Ziegler, Francesco Muntoni, and Laurent Servais. 2024 update: european consensus statement on gene therapy for spinal muscular atrophy. European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society, 51:73-78, Jun 2024. URL: https://doi.org/10.1016/j.ejpn.2024.06.001, doi:10.1016/j.ejpn.2024.06.001. This article has 28 citations.