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Koster KP, Flores-Barrera E, Artur de la Villarmois E, Caballero A, Tseng KY, Yoshii A. Loss of Depalmitoylation Disrupts Homeostatic Plasticity of AMPARs in a Mouse Model of Infantile Neuronal Ceroid Lipofuscinosis. J Neurosci 2023; 43:8317-8335. [PMID: 37884348 PMCID: PMC10711723 DOI: 10.1523/jneurosci.1113-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/28/2023] Open
Abstract
Protein palmitoylation is the only reversible post-translational lipid modification. Palmitoylation is held in delicate balance by depalmitoylation to precisely regulate protein turnover. While over 20 palmitoylation enzymes are known, depalmitoylation is conducted by fewer enzymes. Of particular interest is the lack of the depalmitoylating enzyme palmitoyl-protein thioesterase 1 (PPT1) that causes the devastating pediatric neurodegenerative condition infantile neuronal ceroid lipofuscinosis (CLN1). While most of the research on Ppt1 function has centered on its role in the lysosome, recent findings demonstrated that many Ppt1 substrates are synaptic proteins, including the AMPA receptor (AMPAR) subunit GluA1. Still, the impact of Ppt1-mediated depalmitoylation on synaptic transmission and plasticity remains elusive. Thus, the goal of the present study was to use the Ppt1 -/- mouse model (both sexes) to determine whether Ppt1 regulates AMPAR-mediated synaptic transmission and plasticity, which are crucial for the maintenance of homeostatic adaptations in cortical circuits. Here, we found that basal excitatory transmission in the Ppt1 -/- visual cortex is developmentally regulated and that chemogenetic silencing of the Ppt1 -/- visual cortex excessively enhanced the synaptic expression of GluA1. Furthermore, triggering homeostatic plasticity in Ppt1 -/- primary neurons caused an exaggerated incorporation of GluA1-containing, calcium-permeable AMPARs, which correlated with increased GluA1 palmitoylation. Finally, Ca2+ imaging in awake Ppt1 -/- mice showed visual cortical neurons favor a state of synchronous firing. Collectively, our results elucidate a crucial role for Ppt1 in AMPAR trafficking and show that impeded proteostasis of palmitoylated synaptic proteins drives maladaptive homeostatic plasticity and abnormal recruitment of cortical activity in CLN1.SIGNIFICANCE STATEMENT Neuronal communication is orchestrated by the movement of receptors to and from the synaptic membrane. Protein palmitoylation is the only reversible post-translational lipid modification, a process that must be balanced precisely by depalmitoylation. The significance of depalmitoylation is evidenced by the discovery that mutation of the depalmitoylating enzyme palmitoyl-protein thioesterase 1 (Ppt1) causes severe pediatric neurodegeneration. In this study, we found that the equilibrium provided by Ppt1-mediated depalmitoylation is critical for AMPA receptor (AMPAR)-mediated plasticity and associated homeostatic adaptations of synaptic transmission in cortical circuits. This finding complements the recent explosion of palmitoylation research by emphasizing the necessity of balanced depalmitoylation.
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Affiliation(s)
- Kevin P Koster
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Eden Flores-Barrera
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612
| | | | - Adriana Caballero
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Kuei Y Tseng
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Akira Yoshii
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois 60612
- Department of Pediatrics, University of Illinois at Chicago, Chicago, Illinois 60612
- Department of Neurology, University of Illinois at Chicago, Chicago, Illinois 60612
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Ostergaard JR, Nelvagal HR, Cooper JD. Top-down and bottom-up propagation of disease in the neuronal ceroid lipofuscinoses. Front Neurol 2022; 13:1061363. [PMID: 36438942 PMCID: PMC9692088 DOI: 10.3389/fneur.2022.1061363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 10/28/2022] [Indexed: 11/13/2022] Open
Abstract
Background The Neuronal Ceroid Lipofuscinoses (NCLs) may be considered distinct neurodegenerative disorders with separate underlying molecular causes resulting from monogenetic mutations. An alternative hypothesis is to consider the NCLs as related diseases that share lipofuscin pathobiology as the common core feature, but otherwise distinguished by different a) initial anatomic location, and b) disease propagation. Methods We have tested this hypothesis by comparing known differences in symptomatology and pathology of the CLN1 phenotype caused by complete loss of PPT1 function (i.e., the classical infantile form) and of the classical juvenile CLN3 phenotype. These two forms of NCL represent early onset and rapidly progressing vs. late onset and slowly progressing disease modalities respectively. Results Despite displaying similar pathological endpoints, the clinical phenotypes and the evidence of imaging and postmortem studies reveal strikingly different time courses and distributions of disease propagation. Data from CLN1 disease are indicative of disease propagation from the body, with early effects within the spinal cord and subsequently within the brainstem, the cerebral hemispheres, cerebellum and retina. In contrast, the retina appears to be the most vulnerable organ in CLN3, and the site where pathology is first present. Pathology subsequently is present in the occipital connectome of the CLN3 brain, followed by a top-down propagation in which cerebral and cerebellar atrophy in early adolescence is followed by involvement of the peripheral nerves in later adolescence/early twenties, with the extrapyramidal system also affected during this time course. Discussion The propagation of disease in these two NCLs therefore has much in common with the “Brain-first” vs. “Body-first” models of alpha-synuclein propagation in Parkinson's disease. CLN1 disease represents a “Body-first” or bottom-up disease propagation and CLN3 disease having a “Brain-first” and top-down propagation. It is noteworthy that the varied phenotypes of CLN1 disease, whether it starts in infancy (infantile form) or later in childhood (juvenile form), still fit with our proposed hypothesis of a bottom-up disease propagation in CLN1. Likewise, in protracted CLN3 disease, where both cognitive and motor declines are delayed, the initial manifestations of disease are also seen in the outer retinal layers, i.e., identical to classical Juvenile NCL disease.
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Affiliation(s)
- John R. Ostergaard
- Department of Child and Adolescencet, Centre for Rare Diseases, Aarhus, Denmark
- *Correspondence: John R. Ostergaard
| | - Hemanth R. Nelvagal
- Department of Pediatrics, School of Medicine, Washington University in St Louis, St Louis, MO, United States
- UCL School of Pharmacy, University College London, London, United Kingdom
| | - Jonathan D. Cooper
- Department of Pediatrics, School of Medicine, Washington University in St Louis, St Louis, MO, United States
- Department of Genetics, School of Medicine, Washington University in St Louis, St Louis, MO, United States
- Department of Neurology, School of Medicine, Washington University in St Louis, St Louis, MO, United States
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Hahn A, Sato Y, Ikeda T, Sonoda H, Schmidt M, Pfrimmer C, Boado RJ, Pardridge WM. Treatment of CLN1 disease with a blood-brain barrier penetrating lysosomal enzyme. Mol Genet Metab Rep 2022; 33:100930. [PMID: 36324638 PMCID: PMC9618832 DOI: 10.1016/j.ymgmr.2022.100930] [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] [Received: 08/17/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 11/23/2022] Open
Abstract
Neuronal ceroid lipofuscinosis type 1(CLN1 disease) is a rare autosomal recessive lysosomal storage disease caused by genetic defects of palmitoyl protein thioesterase-1(PPT1), leading to accumulation of lipofuscin granules in brain and progressive neurodegeneration. Psychomotor regression, seizures, loss of vision, and movement disorder begin in infancy and result in early death. Currently, no disease-modifying therapy is available. We report a 68-month-old boy with CLN1 treated on a compassionate use basis weekly for 26 months with a PPT1 enzyme fused to an anti-insulin receptor antibody (AGT-194), thereby enabling penetration of the blood-brain barrier (BBB). During treatment, no side effects were observed, while seizure frequency decreased, life quality improved, and the boy's general condition remained stable. This case documents for the first time that treatment of CLN1 is principally feasible by an intravenous BBB penetrating enzyme replacement therapy using PPT1 fused with the human insulin receptor. Monitoring of side effects raised no unacceptable or unexpected safety concerns.Observed improvement of life quality related to ameliorated epilepsy control raises hope that further robust clinical trials including patients in earlier stages of disease will show positive results.
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Affiliation(s)
- Andreas Hahn
- Department of Child Neurology, Justus-Liebig University Gießen, Germany
| | - Yuji Sato
- JCR Pharmaceuticals, Hyogo, Japan,Corresponding author at: Research and Development, JCR Pharmaceuticals, 3-19 Kasuga-cho, Ashiya, Hyogo 659-0021, Japan.
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Nelvagal HR, Eaton SL, Wang SH, Eultgen EM, Takahashi K, Le SQ, Nesbitt R, Dearborn JT, Siano N, Puhl AC, Dickson PI, Thompson G, Murdoch F, Brennan PM, Gray M, Greenhalgh SN, Tennant P, Gregson R, Clutton E, Nixon J, Proudfoot C, Guido S, Lillico SG, Whitelaw CBA, Lu JY, Hofmann SL, Ekins S, Sands MS, Wishart TM, Cooper JD. Cross-species efficacy of enzyme replacement therapy for CLN1 disease in mice and sheep. J Clin Invest 2022; 132:163107. [PMID: 36040802 PMCID: PMC9566914 DOI: 10.1172/jci163107] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/25/2022] [Indexed: 11/25/2022] Open
Abstract
CLN1 disease, also called infantile neuronal ceroid lipofuscinosis (NCL) or infantile Batten disease, is a fatal neurodegenerative lysosomal storage disorder resulting from mutations in the CLN1 gene encoding the soluble lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1). Therapies for CLN1 disease have proven challenging because of the aggressive disease course and the need to treat widespread areas of the brain and spinal cord. Indeed, gene therapy has proven less effective for CLN1 disease than for other similar lysosomal enzyme deficiencies. We therefore tested the efficacy of enzyme replacement therapy (ERT) by administering monthly infusions of recombinant human PPT1 (rhPPT1) to PPT1-deficient mice (Cln1-/-) and CLN1R151X sheep to assess how to potentially scale up for translation. In Cln1-/- mice, intracerebrovascular (i.c.v.) rhPPT1 delivery was the most effective route of administration, resulting in therapeutically relevant CNS levels of PPT1 activity. rhPPT1-treated mice had improved motor function, reduced disease-associated pathology, and diminished neuronal loss. In CLN1R151X sheep, i.c.v. infusions resulted in widespread rhPPT1 distribution and positive treatment effects measured by quantitative structural MRI and neuropathology. This study demonstrates the feasibility and therapeutic efficacy of i.c.v. rhPPT1 ERT. These findings represent a key step toward clinical testing of ERT in children with CLN1 disease and highlight the importance of a cross-species approach to developing a successful treatment strategy.
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Affiliation(s)
- Hemanth R. Nelvagal
- Department of Pediatrics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
| | - Samantha L. Eaton
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Sophie H. Wang
- Department of Pediatrics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
| | - Elizabeth M. Eultgen
- Department of Pediatrics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
| | - Keigo Takahashi
- Department of Pediatrics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
| | - Steven Q. Le
- Department of Pediatrics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
| | - Rachel Nesbitt
- Department of Medicine, Washington University in St. Louis, School of Medicine, St .Louis, Missouri, USA
| | - Joshua T. Dearborn
- Department of Medicine, Washington University in St. Louis, School of Medicine, St .Louis, Missouri, USA
| | - Nicholas Siano
- Discovery Science Division, Amicus Therapeutics Inc., Philadelphia, Pennsylvania, USA
| | - Ana C. Puhl
- Collaborations Pharmaceuticals Inc., Lab 3510, Raleigh, North Carolina, USA
| | - Patricia I. Dickson
- Department of Pediatrics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
- Department of Genetics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
| | - Gerard Thompson
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor’s Building, Edinburgh, Scotland, United Kingdom
- Department of Clinical Neurosciences, NHS Lothian, Edinburgh, Scotland, United Kingdom
| | - Fraser Murdoch
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Paul M. Brennan
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor’s Building, Edinburgh, Scotland, United Kingdom
- Department of Clinical Neurosciences, NHS Lothian, Edinburgh, Scotland, United Kingdom
| | - Mark Gray
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
- The Large Animal Research and Imaging Facility (LARIF), Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Stephen N. Greenhalgh
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
- The Large Animal Research and Imaging Facility (LARIF), Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Peter Tennant
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
- The Large Animal Research and Imaging Facility (LARIF), Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Rachael Gregson
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
- The Large Animal Research and Imaging Facility (LARIF), Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Eddie Clutton
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
- The Large Animal Research and Imaging Facility (LARIF), Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - James Nixon
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
- The Large Animal Research and Imaging Facility (LARIF), Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Chris Proudfoot
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
- The Large Animal Research and Imaging Facility (LARIF), Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Stefano Guido
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Simon G. Lillico
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - C. Bruce A. Whitelaw
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Jui-Yun Lu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sandra L. Hofmann
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sean Ekins
- Collaborations Pharmaceuticals Inc., Lab 3510, Raleigh, North Carolina, USA
| | - Mark S. Sands
- Department of Medicine, Washington University in St. Louis, School of Medicine, St .Louis, Missouri, USA
- Department of Genetics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
| | - Thomas M. Wishart
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Easter Bush, Scotland, United Kingdom
| | - Jonathan D. Cooper
- Department of Pediatrics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
- Department of Genetics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
- Department of Neurology, Washington University in St. Louis, School of Medicine, St. Louis, Missouri, USA
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Rossini L, Durante C, Marzollo A, Biffi A. New Indications for Hematopoietic Stem Cell Gene Therapy in Lysosomal Storage Disorders. Front Oncol 2022; 12:885639. [PMID: 35646708 PMCID: PMC9136164 DOI: 10.3389/fonc.2022.885639] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/11/2022] [Indexed: 12/04/2022] Open
Abstract
Lysosomal storage disorders (LSDs) are a heterogenous group of disorders due to genetically determined deficits of lysosomal enzymes. The specific molecular mechanism and disease phenotype depends on the type of storage material. Several disorders affect the brain resulting in severe clinical manifestations that substantially impact the expectancy and quality of life. Current treatment modalities for LSDs include enzyme replacement therapy (ERT) and hematopoietic cell transplantation (HCT) from allogeneic healthy donors, but are available for a limited number of disorders and lack efficacy on several clinical manifestations. Hematopoietic stem cell gene therapy (HSC GT) based on integrating lentiviral vectors resulted in robust clinical benefit when administered to patients affected by Metachromatic Leukodystrophy, for whom it is now available as a registered medicinal product. More recently, HSC GT has also shown promising results in Hurler syndrome patients. Here, we discuss possible novel HSC GT indications that are currently under development. If these novel drugs will prove effective, they might represent a new standard of care for these disorders, but several challenges will need to be addresses, including defining and possibly expanding the patient population for whom HSC GT could be efficacious.
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Affiliation(s)
- Linda Rossini
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
| | - Caterina Durante
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
| | - Antonio Marzollo
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Fondazione Citta’ della Speranza, Istituto di Ricerca Pediatrica, Padua, Italy
| | - Alessandra Biffi
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
- *Correspondence: Alessandra Biffi,
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Simonati A, Williams RE. Neuronal Ceroid Lipofuscinosis: The Multifaceted Approach to the Clinical Issues, an Overview. Front Neurol 2022; 13:811686. [PMID: 35359645 PMCID: PMC8961688 DOI: 10.3389/fneur.2022.811686] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/11/2022] [Indexed: 01/04/2023] Open
Abstract
The main aim of this review is to summarize the current state-of-art in the field of childhood Neuronal Ceroid Lipofuscinosis (NCL), a group of rare neurodegenerative disorders. These are genetic diseases associated with the formation of toxic endo-lysosomal storage. Following a brief historical review of the evolution of NCL definition, a clinically-oriented approach is used describing how the early symptoms and signs affecting motor, visual, cognitive domains, and including seizures, may lead clinicians to a rapid molecular diagnosis, avoiding the long diagnostic odyssey commonly observed. We go on to focus on recent advances in NCL research and summarize contributions to knowledge of the pathogenic mechanisms underlying NCL. We describe the large variety of experimental models which have aided this research, as well as the most recent technological developments which have shed light on the main mechanisms involved in the cellular pathology, such as apoptosis and autophagy. The search for innovative therapies is described. Translation of experimental data into therapeutic approaches is being established for several of the NCLs, and one drug is now commercially available. Lastly, we show the importance of palliative care and symptomatic treatments which are still the main therapeutic interventions.
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Affiliation(s)
- Alessandro Simonati
- Departments of Surgery, Dentistry, Paediatrics, and Gynaecology, School of Medicine, University of Verona, Verona, Italy
- Department of Clinical Neuroscience, AOUI-VR, Verona, Italy
- *Correspondence: Alessandro Simonati
| | - Ruth E. Williams
- Department of Children's Neuroscience, Evelina London Children's Hospital, London, United Kingdom
- Ruth E. Williams
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Trivisano M, Ferretti A, Calabrese C, Pietrafusa N, Piscitello L, Carfi' Pavia G, Vigevano F, Specchio N. Neurophysiological Findings in Neuronal Ceroid Lipofuscinoses. Front Neurol 2022; 13:845877. [PMID: 35280270 PMCID: PMC8916234 DOI: 10.3389/fneur.2022.845877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 01/20/2022] [Indexed: 11/19/2022] Open
Abstract
Neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of neurodegenerative diseases, characterized by progressive cerebral atrophy due to lysosomal storage disorder. Common clinical features include epileptic seizures, progressive cognitive and motor decline, and visual failure, which occur over different time courses according to subtypes. During the latest years, many advances have been done in the field of targeted treatments, and in the next future, gene therapies and enzyme replacement treatments may be available for several NCL variants. Considering that there is rapid disease progression in NCLs, an early diagnosis is crucial, and neurophysiological features might have a key role for this purpose. Across the different subtypes of NCLs, electroencephalogram (EEG) is characterized by a progressive deterioration of cerebral activity with slowing of background activity and disappearance of spindles during sleep. Some types of heterogeneous abnormalities, diffuse or focal, prevalent over temporal and occipital regions, are described in many NCL variants. Photoparoxysmal response to low-frequency intermittent photic stimulation (IPS) is a typical EEG finding, mostly described in CLN2, CLN5, and CLN6 diseases. Visual evoked potentials (VEPs) allow to monitor the visual functions, and the lack of response at electroretinogram (ERG) reflects retinal neurodegeneration. Taken together, EEG, VEPs, and ERG may represent essential tools toward an early diagnosis of NCLs.
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Affiliation(s)
| | | | | | | | | | | | | | - Nicola Specchio
- Rare and Complex Epilepsy Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
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