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Passchier EMJ, Bisseling Q, Helman G, van Spaendonk RML, Simons C, Olsthoorn RCL, van der Veen H, Abbink TEM, van der Knaap MS, Min R. Megalencephalic leukoencephalopathy with subcortical cysts: a variant update and review of the literature. Front Genet 2024; 15:1352947. [PMID: 38487253 PMCID: PMC10938252 DOI: 10.3389/fgene.2024.1352947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Accepted: 01/29/2024] [Indexed: 03/17/2024] Open
Abstract
The leukodystrophy megalencephalic leukoencephalopathy with subcortical cysts (MLC) is characterized by infantile-onset macrocephaly and chronic edema of the brain white matter. With delayed onset, patients typically experience motor problems, epilepsy and slow cognitive decline. No treatment is available. Classic MLC is caused by bi-allelic recessive pathogenic variants in MLC1 or GLIALCAM (also called HEPACAM). Heterozygous dominant pathogenic variants in GLIALCAM lead to remitting MLC, where patients show a similar phenotype in early life, followed by normalization of white matter edema and no clinical regression. Rare patients with heterozygous dominant variants in GPRC5B and classic MLC were recently described. In addition, two siblings with bi-allelic recessive variants in AQP4 and remitting MLC have been identified. The last systematic overview of variants linked to MLC dates back to 2006. We provide an updated overview of published and novel variants. We report on genetic variants from 508 patients with MLC as confirmed by MRI diagnosis (258 from our database and 250 extracted from 64 published reports). We describe 151 unique MLC1 variants, 29 GLIALCAM variants, 2 GPRC5B variants and 1 AQP4 variant observed in these MLC patients. We include experiments confirming pathogenicity for some variants, discuss particularly notable variants, and provide an overview of recent scientific and clinical insight in the pathophysiology of MLC.
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Affiliation(s)
- Emma M. J. Passchier
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Quinty Bisseling
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Guy Helman
- Translational Bioinformatics, Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC, Australia
| | | | - Cas Simons
- Translational Bioinformatics, Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research, Sydney, NSW, Australia
| | | | - Hieke van der Veen
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Truus E. M. Abbink
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Marjo S. van der Knaap
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
| | - Rogier Min
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children’s Hospital, Amsterdam University Medical Center, Amsterdam Neuroscience, Amsterdam, Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, Netherlands
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Passchier EMJ, Kerst S, Brouwers E, Hamilton EMC, Bisseling Q, Bugiani M, Waisfisz Q, Kitchen P, Unger L, Breur M, Hoogterp L, de Vries SI, Abbink TEM, Kole MHP, Leurs R, Vischer HF, Brignone MS, Ambrosini E, Feillet F, Born AP, Epstein LG, Mansvelder HD, Min R, van der Knaap MS. Aquaporin-4 and GPRC5B: old and new players in controlling brain oedema. Brain 2023:7152690. [PMID: 37143309 PMCID: PMC10393393 DOI: 10.1093/brain/awad146] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 03/30/2023] [Accepted: 04/14/2023] [Indexed: 05/06/2023] Open
Abstract
Brain oedema is a life-threatening complication of various neurological conditions. Understanding molecular mechanisms of brain volume regulation is critical for therapy development. Unique insight comes from monogenic diseases characterized by chronic brain oedema, of which megalencephalic leukoencephalopathy with subcortical cysts (MLC) is the prototype. Variants in MLC1 or GLIALCAM, encoding proteins involved in astrocyte volume regulation, are the main causes of MLC. In some patients the genetic cause remains unknown. We performed genetic studies to identify novel gene variants in MLC patients, diagnosed by clinical and MRI features, without MLC1 or GLIALCAM variants. We determined subcellular localization of the related novel proteins in cells and in human brain tissue. We investigated functional consequences of the newly identified variants on volume regulation pathways using cell volume measurements, biochemical analysis and electrophysiology. We identified a novel homozygous variant in AQP4, encoding the water channel aquaporin-4, in two siblings, and two de novo heterozygous variants in GPRC5B, encoding the orphan G protein-coupled receptor GPRC5B, in three unrelated patients. The AQP4 variant disrupts membrane localization and thereby channel function. GPRC5B, like MLC1, GlialCAM and aquaporin-4, is expressed in astrocyte endfeet in human brain. Cell volume regulation is disrupted in GPRC5B patient-derived lymphoblasts. GPRC5B functionally interacts with ion channels involved in astrocyte volume regulation. In conclusion, we identify aquaporin-4 and GPRC5B as old and new players in genetic brain oedema. Our findings shed light on the protein complex involved in astrocyte volume regulation and identify GPRC5B as novel potentially druggable target for treating brain oedema.
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Affiliation(s)
- Emma M J Passchier
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Sven Kerst
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Eelke Brouwers
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Eline M C Hamilton
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Quinty Bisseling
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Marianna Bugiani
- Department of Pathology, Amsterdam Leukodystrophy Center, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Quinten Waisfisz
- Department of Human Genetics, Amsterdam University Medical Centers location Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Philip Kitchen
- School of Biosciences, College of Health and Life Sciences, Aston University, Birmingham, UK
| | - Lucas Unger
- School of Biosciences, College of Health and Life Sciences, Aston University, Birmingham, UK
| | - Marjolein Breur
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Pathology, Amsterdam Leukodystrophy Center, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Leoni Hoogterp
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Sharon I de Vries
- Department of Axonal Signaling, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Truus E M Abbink
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Maarten H P Kole
- Department of Axonal Signaling, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Rob Leurs
- Division of Medicinal Chemistry, Faculty of Science, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Henry F Vischer
- Division of Medicinal Chemistry, Faculty of Science, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Maria S Brignone
- Department of Neuroscience, Istituto Superiore di Sanità, Rome, Italy
| | - Elena Ambrosini
- Department of Neuroscience, Istituto Superiore di Sanità, Rome, Italy
| | - François Feillet
- Reference Center for Inherited Metabolic Diseases, INSERM UMR_S 1256 NGERE, Nancy University Hospital, Vandoeuvre-lès-Nancy, France
| | - Alfred P Born
- Department of Pediatrics and Adolescent Medicine, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Leon G Epstein
- Division of Neurology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois; Departments of Pediatrics and Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Rogier Min
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Marjo S van der Knaap
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Centers, location Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, Amsterdam, The Netherlands
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