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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] [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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Amin M, Vignal C, Hamed AAA, Mohammed IN, Elseed MA, Drunat S, Babai A, Eltaraifee E, Elbadi I, Abubaker R, Mustafa D, Yahia A, Koko M, Osman M, Bakhit Y, Elshafea A, Alsiddig M, Haroun S, Lelay G, Elsayed LEO, Ahmed AE, Boespflug-Tanguy O, Dorboz I. Novel variants causing megalencephalic leukodystrophy in Sudanese families. J Hum Genet 2021; 67:127-132. [PMID: 34504271 DOI: 10.1038/s10038-021-00945-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/12/2021] [Accepted: 05/28/2021] [Indexed: 11/09/2022]
Abstract
Mutations in MLC1 cause megalencephalic leukoencephalopathy with subcortical cysts (MLC), a rare form of leukodystrophy characterized by macrocephaly, epilepsy, spasticity, and slow mental deterioration. Genetic studies of MLC are lacking from many parts of the world, especially in Sub-Saharan Africa. Genomic DNA was extracted for 67 leukodystrophic patients from 43 Sudanese families. Mutations were screened using the NGS panel testing 139 leukodystrophies and leukoencephalopathies causing genes (NextSeq500 Illumina). Five homozygous MLC1 variants were discovered in seven patients from five distinct families, including three consanguineous families from the same region of Sudan. Three variants were missense (c.971 T > G, p.Ile324Ser; c.344 T > C, p.Phe115Ser; and c.881 C > T, p.Pro294Leu), one duplication (c.831_838dupATATCTGT, p.Ser280Tyrfs*8), and one synonymous/splicing-site mutation (c.762 C > T, p.Ser254). The segregation pattern was consistent with autosomal recessive inheritance. The clinical presentation and brain MRI of the seven affected patients were consistent with the diagnosis of MLC1. Due to the high frequency of distinct MLC1 mutations found in our leukodystrophic Sudanese families, we analyzed the coding sequence of MLC1 gene in 124 individuals from the Sudanese genome project in comparison with the 1000-genome project. We found that Sudan has the highest proportion of deleterious variants in MLC1 gene compared with other populations from the 1000-genome project.
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Affiliation(s)
- Mutaz Amin
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan.,Université de Paris, NeuroDiderot, UMR 1141, INSERM, Paris, France
| | - Cedric Vignal
- Unité de Génétique Moleculaire, Departement de Genetique Médicale, APHP, Hopital Robert-Debré, Paris, France
| | - Ahlam A A Hamed
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | | | - Maha A Elseed
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Severine Drunat
- Université de Paris, NeuroDiderot, UMR 1141, INSERM, Paris, France.,Unité de Génétique Moleculaire, Departement de Genetique Médicale, APHP, Hopital Robert-Debré, Paris, France
| | - Arwa Babai
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | | | - Iman Elbadi
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Rayan Abubaker
- Department of Molecular Biology, Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | - Doaa Mustafa
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Ashraf Yahia
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan.,Institut du Cerveau, INSERM U1127, CNRS UMR7225, Sorbonne Université, Paris, France
| | - Mahmoud Koko
- Department of Molecular Biology, Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | - Melka Osman
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Yousuf Bakhit
- Faculty of Dentistry, University of Khartoum, Khartoum, Sudan
| | - Azza Elshafea
- Department of Molecular Biology, Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | | | - Sahwah Haroun
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Gurvan Lelay
- Université de Paris, NeuroDiderot, UMR 1141, INSERM, Paris, France
| | | | - Ammar E Ahmed
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Odile Boespflug-Tanguy
- Université de Paris, NeuroDiderot, UMR 1141, INSERM, Paris, France.,Neuropediatrie, LEUKOFRANCE, APHP, Hopital Robert-Debré, Paris, France
| | - Imen Dorboz
- Université de Paris, NeuroDiderot, UMR 1141, INSERM, Paris, France.
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Estévez R, Elorza-Vidal X, Gaitán-Peñas H, Pérez-Rius C, Armand-Ugón M, Alonso-Gardón M, Xicoy-Espaulella E, Sirisi S, Arnedo T, Capdevila-Nortes X, López-Hernández T, Montolio M, Duarri A, Teijido O, Barrallo-Gimeno A, Palacín M, Nunes V. Megalencephalic leukoencephalopathy with subcortical cysts: A personal biochemical retrospective. Eur J Med Genet 2018; 61:50-60. [DOI: 10.1016/j.ejmg.2017.10.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/14/2017] [Accepted: 10/22/2017] [Indexed: 12/22/2022]
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Mahmoud IG, Mahmoud M, Refaat M, Girgis M, Waked N, El Badawy A, Selim L, Hassan S, Abdel Aleem AK. Clinical, neuroimaging, and genetic characteristics of megalencephalic leukoencephalopathy with subcortical cysts in Egyptian patients. Pediatr Neurol 2014; 50:140-8. [PMID: 24315536 DOI: 10.1016/j.pediatrneurol.2013.10.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/03/2013] [Accepted: 10/16/2013] [Indexed: 01/07/2023]
Abstract
BACKGROUND Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare and genetically heterogeneous cerebral white matter disease. Clinically, it is characterized by macrocephaly, developmental delay, and seizures. We explore the clinical spectrum, neuroimaging characteristics, and gene involvement in the first patients with megalencephalic leukoencephalopathy with subcortical cysts described from Egypt. PATIENTS Six patients were enrolled from three unrelated families. Patient inclusion criteria were macrocephaly, developmental delay, normal urinary organic acids, and brain imaging of diffuse cerebral white matter involvement. Direct sequencing of the MLC1 gene in patients' families and GliaCAM in one questionable case was performed using BigDye Terminator cycle sequencing. RESULTS Clinical heterogeneity, both intra- and interfamilial, was clearly evident. Developmental delays ranged from globally severe or moderate to mild delay in achieving walking or speech. Head circumference above the ninety-seventh percentile was a constant feature. Neuroimaging featured variability in white matter involvement and subcortical cysts. However, findings of posterior fossa changes and brain stem atrophy were frequently (66.6%) identified in these Egyptian patients. Discrepancy between severe brain involvement and normal mental functions was evident, particularly in patients from the third family. MLC1 mutations were confirmed in all patients. Deletion/insertion mutation in exon 11 (c.908-918delinsGCA, p.Val303 Gly fsX96) was recurrent in two families, whereas a missense mutation in exon 10 (c.880 C > T, p.Pro294Ser) was identified in the third family. CONCLUSIONS This report extends our knowledge of the clinical and neuroimaging features of megalencephalic leukoencephalopathy with subcortical cysts. It confirms the apparent lack of selective disadvantage of MLC1 mutations on gamete conception and transmission as supported by the presence of multiple affected siblings in Egyptian families.
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Affiliation(s)
- Iman G Mahmoud
- Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt
| | - Marwa Mahmoud
- Stem Cell Research Laboratory, Centre for Advanced Sciences-National Research Centre, Cairo, Egypt
| | - Miral Refaat
- Stem Cell Research Laboratory, Centre for Advanced Sciences-National Research Centre, Cairo, Egypt
| | - Marian Girgis
- Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt
| | - Nevin Waked
- Department of Pediatrics, 6(th) October University, Cairo, Egypt
| | - Ameera El Badawy
- Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt
| | - Laila Selim
- Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt
| | - Sawsan Hassan
- Genetics and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt
| | - Alice K Abdel Aleem
- Stem Cell Research Laboratory, Centre for Advanced Sciences-National Research Centre, Cairo, Egypt; Neurogenetics Laboratory, Weill Cornell Medical College in Qatar, Doha, Qatar; Department of Neurology, Weill Cornell Medical College, New York, New York.
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