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Di Donato N, Guerrini R, Billington CJ, Barkovich AJ, Dinkel P, Freri E, Heide M, Gershon ES, Gertler TS, Hopkin RJ, Jacob S, Keedy SK, Kooshavar D, Lockhart PJ, Lohmann DR, Mahmoud IG, Parrini E, Schrock E, Severi G, Timms AE, Webster RI, Willis MJH, Zaki MS, Gleeson JG, Leventer RJ, Dobyns WB. Monoallelic and biallelic mutations in RELN underlie a graded series of neurodevelopmental disorders. Brain 2022; 145:3274-3287. [PMID: 35769015 PMCID: PMC9989350 DOI: 10.1093/brain/awac164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/02/2022] [Accepted: 04/19/2022] [Indexed: 11/14/2022] Open
Abstract
Reelin, a large extracellular protein, plays several critical roles in brain development and function. It is encoded by RELN, first identified as the gene disrupted in the reeler mouse, a classic neurological mutant exhibiting ataxia, tremors and a 'reeling' gait. In humans, biallelic variants in RELN have been associated with a recessive lissencephaly variant with cerebellar hypoplasia, which matches well with the homozygous mouse mutant that has abnormal cortical structure, small hippocampi and severe cerebellar hypoplasia. Despite the large size of the gene, only 11 individuals with RELN-related lissencephaly with cerebellar hypoplasia from six families have previously been reported. Heterozygous carriers in these families were briefly reported as unaffected, although putative loss-of-function variants are practically absent in the population (probability of loss of function intolerance = 1). Here we present data on seven individuals from four families with biallelic and 13 individuals from seven families with monoallelic (heterozygous) variants of RELN and frontotemporal or temporal-predominant lissencephaly variant. Some individuals with monoallelic variants have moderate frontotemporal lissencephaly, but with normal cerebellar structure and intellectual disability with severe behavioural dysfunction. However, one adult had abnormal MRI with normal intelligence and neurological profile. Thorough literature analysis supports a causal role for monoallelic RELN variants in four seemingly distinct phenotypes including frontotemporal lissencephaly, epilepsy, autism and probably schizophrenia. Notably, we observed a significantly higher proportion of loss-of-function variants in the biallelic compared to the monoallelic cohort, where the variant spectrum included missense and splice-site variants. We assessed the impact of two canonical splice-site variants observed as biallelic or monoallelic variants in individuals with moderately affected or normal cerebellum and demonstrated exon skipping causing in-frame loss of 46 or 52 amino acids in the central RELN domain. Previously reported functional studies demonstrated severe reduction in overall RELN secretion caused by heterozygous missense variants p.Cys539Arg and p.Arg3207Cys associated with lissencephaly suggesting a dominant-negative effect. We conclude that biallelic variants resulting in complete absence of RELN expression are associated with a consistent and severe phenotype that includes cerebellar hypoplasia. However, reduced expression of RELN remains sufficient to maintain nearly normal cerebellar structure. Monoallelic variants are associated with incomplete penetrance and variable expressivity even within the same family and may have dominant-negative effects. Reduced RELN secretion in heterozygous individuals affects only cortical structure whereas the cerebellum remains intact. Our data expand the spectrum of RELN-related neurodevelopmental disorders ranging from lethal brain malformations to adult phenotypes with normal brain imaging.
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Affiliation(s)
- Nataliya Di Donato
- Institute for Clinical Genetics, University Hospital, TU Dresden, 01307 Dresden, Germany
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, 50139 Florence, Italy
| | - Charles J Billington
- Department of Pediatrics, Division of Genetics and Metabolism, University of Minnesota, Minneapolis, MN 55454, USA
| | - A James Barkovich
- Departments of Radiology and Biomedical Imaging, Neurology, Pediatrics, and Neurosurgery, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Philine Dinkel
- Institute for Clinical Genetics, University Hospital, TU Dresden, 01307 Dresden, Germany
| | - Elena Freri
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy
| | - Michael Heide
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- German Primate Center, Leibniz Institute for Primate Research, 37077 Goettingen, Germany
| | - Elliot S Gershon
- Department of Human Genetics, The University of Chicago, Chicago, IL 60637, USA
- Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL 60637, USA
| | - Tracy S Gertler
- Division of Neurology, Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, USA
| | - Robert J Hopkin
- Cincinnati Children's Hospital Medical Center and University of Cincinnati College of Medicine, Department of Pediatrics, Division of Human Genetics, Cincinnati, OH 45229, USA
| | - Suma Jacob
- Department of Psychiatry, University of Minnesota, Minneapolis, MN 55454, USA
| | - Sarah K Keedy
- Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL 60637, USA
| | - Daniz Kooshavar
- Bruce Lefory Centre, Murdoch Children's Research Institute and University of Melbourne Department of Pediatrics, Melbourne 3052, Australia
| | - Paul J Lockhart
- Bruce Lefory Centre, Murdoch Children's Research Institute and University of Melbourne Department of Pediatrics, Melbourne 3052, Australia
| | - Dietmar R Lohmann
- Institut fur Humangenetik, Universitatsklinikum Essen, 45147 Essen, Germany
| | - Iman G Mahmoud
- Pediatric Neurology Department, Cairo University Children's Hospital, Cairo, Egypt
| | - Elena Parrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, 50139 Florence, Italy
| | - Evelin Schrock
- Institute for Clinical Genetics, University Hospital, TU Dresden, 01307 Dresden, Germany
| | - Giulia Severi
- Medical Genetics Unit, S. Orsola-Malpighi Hospital, 40138 Bologna, Italy
| | - Andrew E Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Richard I Webster
- T. Y. Nelson Department of Neurology and Neurosurgery, The Children's Hospital at Westmead, Sydney 2145, Australia
| | - Mary J H Willis
- Uniformed Services University School of Medicine and Naval Medical Center, Department of Pediatrics, San Diego, CA 92134, USA
| | - Maha S Zaki
- Pediatric Neurology Department, Cairo University Children's Hospital, Cairo, Egypt
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo Governorate 12622, Egypt
| | - Joseph G Gleeson
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA
| | - Richard J Leventer
- Department of Neurology, Royal Children's Hospital, Murdoch Children's Research Institute and University of Melbourne Department of Pediatrics, Melbourne 3052, Australia
| | - William B Dobyns
- Department of Pediatrics, Division of Genetics and Metabolism, University of Minnesota, Minneapolis, MN 55454, USA
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Leifeld J, Förster E, Reiss G, Hamad MIK. Considering the Role of Extracellular Matrix Molecules, in Particular Reelin, in Granule Cell Dispersion Related to Temporal Lobe Epilepsy. Front Cell Dev Biol 2022; 10:917575. [PMID: 35733853 PMCID: PMC9207388 DOI: 10.3389/fcell.2022.917575] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 05/23/2022] [Indexed: 11/13/2022] Open
Abstract
The extracellular matrix (ECM) of the nervous system can be considered as a dynamically adaptable compartment between neuronal cells, in particular neurons and glial cells, that participates in physiological functions of the nervous system. It is mainly composed of carbohydrates and proteins that are secreted by the different kinds of cell types found in the nervous system, in particular neurons and glial cells, but also other cell types, such as pericytes of capillaries, ependymocytes and meningeal cells. ECM molecules participate in developmental processes, synaptic plasticity, neurodegeneration and regenerative processes. As an example, the ECM of the hippocampal formation is involved in degenerative and adaptive processes related to epilepsy. The role of various components of the ECM has been explored extensively. In particular, the ECM protein reelin, well known for orchestrating the formation of neuronal layer formation in the cerebral cortex, is also considered as a player involved in the occurrence of postnatal granule cell dispersion (GCD), a morphologically peculiar feature frequently observed in hippocampal tissue from epileptic patients. Possible causes and consequences of GCD have been studied in various in vivo and in vitro models. The present review discusses different interpretations of GCD and different views on the role of ECM protein reelin in the formation of this morphological peculiarity.
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Affiliation(s)
- Jennifer Leifeld
- Department of Neuroanatomy and Molecular Brain Research, Medical Faculty, Ruhr University Bochum, Bochum, Germany
- Department of Biochemistry I—Receptor Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum, Germany
- *Correspondence: Jennifer Leifeld, ; Eckart Förster,
| | - Eckart Förster
- Department of Neuroanatomy and Molecular Brain Research, Medical Faculty, Ruhr University Bochum, Bochum, Germany
- *Correspondence: Jennifer Leifeld, ; Eckart Förster,
| | - Gebhard Reiss
- Institute for Anatomy and Clinical Morphology, School of Medicine, Faculty of Health, Witten/ Herdecke University, Witten, Germany
| | - Mohammad I. K. Hamad
- Institute for Anatomy and Clinical Morphology, School of Medicine, Faculty of Health, Witten/ Herdecke University, Witten, Germany
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The Reeler Mouse: A Translational Model of Human Neurological Conditions, or Simply a Good Tool for Better Understanding Neurodevelopment? J Clin Med 2019; 8:jcm8122088. [PMID: 31805691 PMCID: PMC6947477 DOI: 10.3390/jcm8122088] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 12/25/2022] Open
Abstract
The first description of the Reeler mutation in mouse dates to more than fifty years ago, and later, its causative gene (reln) was discovered in mouse, and its human orthologue (RELN) was demonstrated to be causative of lissencephaly 2 (LIS2) and about 20% of the cases of autosomal-dominant lateral temporal epilepsy (ADLTE). In both human and mice, the gene encodes for a glycoprotein referred to as reelin (Reln) that plays a primary function in neuronal migration during development and synaptic stabilization in adulthood. Besides LIS2 and ADLTE, RELN and/or other genes coding for the proteins of the Reln intracellular cascade have been associated substantially to other conditions such as spinocerebellar ataxia type 7 and 37, VLDLR-associated cerebellar hypoplasia, PAFAH1B1-associated lissencephaly, autism, and schizophrenia. According to their modalities of inheritances and with significant differences among each other, these neuropsychiatric disorders can be modeled in the homozygous (reln−/−) or heterozygous (reln+/−) Reeler mouse. The worth of these mice as translational models is discussed, with focus on their construct and face validity. Description of face validity, i.e., the resemblance of phenotypes between the two species, centers onto the histological, neurochemical, and functional observations in the cerebral cortex, hippocampus, and cerebellum of Reeler mice and their human counterparts.
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Fitsiori A, Hiremath SB, Boto J, Garibotto V, Vargas MI. Morphological and Advanced Imaging of Epilepsy: Beyond the Basics. CHILDREN (BASEL, SWITZERLAND) 2019; 6:E43. [PMID: 30862078 PMCID: PMC6462967 DOI: 10.3390/children6030043] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 02/27/2019] [Accepted: 03/05/2019] [Indexed: 12/26/2022]
Abstract
The etiology of epilepsy is variable and sometimes multifactorial. Clinical course and response to treatment largely depend on the precise etiology of the seizures. Along with the electroencephalogram (EEG), neuroimaging techniques, in particular, magnetic resonance imaging (MRI), are the most important tools for determining the possible etiology of epilepsy. Over the last few years, there have been many developments in data acquisition and analysis for both morphological and functional neuroimaging of people suffering from this condition. These innovations have increased the detection of underlying structural pathologies, which have till recently been classified as "cryptogenic" epilepsy. Cryptogenic epilepsy is often refractory to anti-epileptic drug treatment. In drug-resistant patients with structural or consistent functional lesions related to the epilepsy syndrome, surgery is the only treatment that can offer a seizure-free outcome. The pre-operative detection of the underlying structural condition increases the odds of successful surgical treatment of pharmacoresistant epilepsy. This article provides a comprehensive overview of neuroimaging techniques in epilepsy, highlighting recent advances and innovations and summarizes frequent etiologies of epilepsy in order to improve the diagnosis and management of patients suffering from seizures, especially young patients and children.
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Affiliation(s)
- Aikaterini Fitsiori
- Unit of Neurodiagnostic, Division of Neuroradiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1205 Geneva, Switzerland.
| | | | - José Boto
- Unit of Neurodiagnostic, Division of Neuroradiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1205 Geneva, Switzerland.
| | - Valentina Garibotto
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital and Faculty of Medicine, Geneva University, 1205 Geneva, Switzerland.
| | - Maria Isabel Vargas
- Unit of Neurodiagnostic, Division of Neuroradiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1205 Geneva, Switzerland.
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