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Shokhen M, Walikonis R, Uversky VN, Allbeck A, Zezelic C, Feldman D, Levy NS, Levy AP. Molecular modeling of ARF6 dysregulation caused by mutations in IQSEC2. J Biomol Struct Dyn 2024; 42:1268-1279. [PMID: 37078745 DOI: 10.1080/07391102.2023.2199085] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 03/29/2023] [Indexed: 04/21/2023]
Abstract
IQSEC2 gene mutations are associated with epilepsy, autism, and intellectual disability. The primary function IQSEC2, mediated via its Sec 7 domain, is to act as a guanine nucleotide exchange factor for ARF6. We sought to develop a molecular model, which may explain the aberrant Sec 7 activity on ARF6 of different human IQSEC2 mutations. We integrated experimental data of IQSEC2 mutants with protein structure prediction by the RaptorX server combined with molecular modeling and molecular dynamics simulations. Normally, apocalmodulin (apoCM) binds to IQSEC2 resulting in its N-terminal fragment inhibiting access of its Sec 7 domain to ARF6. An increase in Ca2+ concentration destabilizes the interaction of IQSEC2 with apoCM and removes steric hindrance of Sec 7 binding with ARF6. Mutations at amino acid residue 350 of IQSEC2 result in loss of steric hindrance of Sec 7 binding with ARF6 leading to constitutive activation of ARF6 by Sec 7. On the other hand, a mutation at amino acid residue 359 of IQSEC2 results in constitutive hindrance of Sec 7 binding to ARF6 leading to the loss of the ability of IQSEC2 to activate ARF6. These studies provide a model for dysregulation of IQSEC2 Sec 7 activity by mutant IQSEC2 proteins.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Michael Shokhen
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Randall Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Vladimir N Uversky
- Department of Molecular Medicine and Byrd Alzheimer's Center and Research Institute, University of South Florida, Tampa, Florida, USA
| | - Amnon Allbeck
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Camryn Zezelic
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Danielle Feldman
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nina S Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Levy NS, Borisov V, Lache O, Levy AP. Molecular Insights into IQSEC2 Disease. Int J Mol Sci 2023; 24. [PMID: 36902414 DOI: 10.3390/ijms24054984] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/02/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Recent insights into IQSEC2 disease are summarized in this review as follows: (1) Exome sequencing of IQSEC2 patient DNA has led to the identification of numerous missense mutations that delineate at least six and possibly seven essential functional domains present in the IQSEC2 gene. (2) Experiments using IQSEC2 transgenic and knockout (KO) mouse models have recapitulated the presence of autistic-like behavior and epileptic seizures in affected animals; however, seizure severity and etiology appear to vary considerably between models. (3) Studies in IQSEC2 KO mice reveal that IQSEC2 is involved in inhibitory as well as stimulatory neurotransmission. The overall picture appears to be that mutated or absent IQSEC2 arrests neuronal development, resulting in immature neuronal networks. Subsequent maturation is aberrant, leading to increased inhibition and reduced neuronal transmission. (4) The levels of Arf6-GTP remain constitutively high in IQSEC2 knockout mice despite the absence of IQSEC2 protein, indicating impaired regulation of the Arf6 guanine nucleotide exchange cycle. (5) A new therapy that has been shown to reduce the seizure burden for the IQSEC2 A350V mutation is heat treatment. Induction of the heat shock response may be responsible for this therapeutic effect.
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Jada R, Borisov V, Laury E, Halpert S, Levy NS, Wagner S, Netser S, Walikonis R, Carmi I, Berlin S, Levy AP. Daily Brief Heat Therapy Reduces Seizures in A350V IQSEC2 Mice and Is Associated with Correction of AMPA Receptor-Mediated Synaptic Dysfunction. Int J Mol Sci 2023; 24. [PMID: 36835332 DOI: 10.3390/ijms24043924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/12/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Purposeful induction of fever for healing, including the treatment of epilepsy, was used over 2000 years ago by Hippocrates. More recently, fever has been demonstrated to rescue behavioral abnormalities in children with autism. However, the mechanism of fever benefit has remained elusive due in large part to the lack of appropriate human disease models recapitulating the fever effect. Pathological mutations in the IQSEC2 gene are frequently seen in children presenting with intellectual disability, autism and epilepsy. We recently described a murine A350V IQSEC2 disease model, which recapitulates important aspects of the human A350V IQSEC2 disease phenotype and the favorable response to a prolonged and sustained rise in body core temperature in a child with the mutation. Our goal has been to use this system to understand the mechanism of fever benefit and then develop drugs that can mimic this effect and reduce IQSEC2-associated morbidity. In this study, we first demonstrate a reduction in seizures in the mouse model following brief periods of heat therapy, similar to what was observed in a child with the mutation. We then show that brief heat therapy is associated with the correction of synaptic dysfunction in neuronal cultures of A350V mice, likely mediated by Arf6-GTP.
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Shoubridge C, Dudding-Byth T, Pasquier L, Goel H, Yap P, Mcconnell V. IQSEC2-related encephalopathy in males due to missense variants in the PH domain. Clin Genet 2022; 102:72-77. [PMID: 35347702 PMCID: PMC9325495 DOI: 10.1111/cge.14136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 11/29/2022]
Abstract
Pathogenic variants in IQ motif and SEC7 domain containing protein 2 (IQSEC2) gene cause a variety of neurodevelopmental disorders, with intellectual disability as a uniform feature. We report five cases, each with a novel missense variant in the pleckstrin homology (PH) domain of the IQSEC2 protein. Male patients all present with moderate to profound intellectual disability, significant delays or absent language and speech and variable seizures. We describe the phenotypic spectrum associated with missense variants in PH domain of IQSEC2, further delineating the genotype–phenotype correlation for this X‐linked gene.
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Affiliation(s)
- Cheryl Shoubridge
- Robinson Research Institute, and Adelaide Medical School, University of Adelaide, South Australia, Australia
| | | | - Laurent Pasquier
- CHU Rennes, Service de Génétique Clinique, Centre de Référence Déficiences Intellectuelles Hôpital Sud, Rennes, France
| | - Himanshu Goel
- Hunter Genetics, Waratah, New South Wales, Australia
| | - Patrick Yap
- Genetic Health Service New Zealand (Northern Hub), Auckland, New Zealand
| | - Vivienne Mcconnell
- Northern Ireland Regional Genetics Service, Belfast City Hospital, Belfast Health & Social Care Trust, Belfast, UK
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Jada R, Zag L, Borisov V, Levy NS, Netser S, Jabarin R, Wagner S, Schragenheim-Rozales K, Shalgi R, Levy AP. Housing of A350V IQSEC2 pups at 37 °C ambient temperature prevents seizures and permits the development of social vocalizations in adulthood. Int J Hyperthermia 2021; 38:1495-1501. [PMID: 34666607 DOI: 10.1080/02656736.2021.1988730] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
OBJECTIVES Mutations in the human IQSEC2 gene are associated with drug-resistant epilepsy and severe behavioral dysfunction. We have focused on understanding one human IQSEC2 missense mutation (A350V) for which we have created a corresponding A350V IQSEC2 mouse model by CRISPR which demonstrates seizures when the mice are 15-20 days old and impaired social vocalizations in adulthood. We observed that a child with the A350V mutation stops having seizures when experiencing a fever of greater than 38 °C. In this study, we first sought to determine if we could recapitulate this phenomenon in A350V 15-20 day old mice using a previously established protocol to raise body temperature to 39 °C achieved by housing the mice at 37 °C. We then sought to determine if mice in whom seizure activity had been prevented as pups would develop social vocalization activity in adulthood. METHODS 15-20 day old A350V male mice were housed either at 37 °C or 22 °C. Ultrasonic vocalizations of these mice were assessed at 8-10 weeks in response to a female stimulus. RESULTS Housing of 15-20 day old A350V mice at 37 °C resulted in a reduction in lethal seizures to 2% (1/41) compared to 45% (48/108) in mice housed at 22 °C, p = 0.0001. Adult A350V mice who had been housed at 37 °C as pups displayed a significant improvement in the production of social vocalizations. CONCLUSION Raising the body temperature by raising the ambient temperature might provide a means to reduce seizures associated with the A350V IQSEC2 mutation and thereby allow for an improved neurodevelopmental trajectory.
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Affiliation(s)
- Reem Jada
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Liron Zag
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Veronika Borisov
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nina S Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Shai Netser
- Faculty of Natural Sciences, Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Renad Jabarin
- Faculty of Natural Sciences, Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Shlomo Wagner
- Faculty of Natural Sciences, Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | | | - Reut Shalgi
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Mehta A, Shirai Y, Kouyama-Suzuki E, Zhou M, Yoshizawa T, Yanagawa T, Mori T, Tabuchi K. IQSEC2 Deficiency Results in Abnormal Social Behaviors Relevant to Autism by Affecting Functions of Neural Circuits in the Medial Prefrontal Cortex. Cells 2021; 10:2724. [PMID: 34685703 PMCID: PMC8534507 DOI: 10.3390/cells10102724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 12/28/2022] Open
Abstract
IQSEC2 is a guanine nucleotide exchange factor (GEF) for ADP-ribosylation factor 6 (Arf6), of which protein is exclusively localized to the postsynaptic density of the excitatory synapse. Human genome studies have revealed that the IQSEC2 gene is associated with X-linked neurodevelopmental disorders, such as intellectual disability (ID), epilepsy, and autism. In this study, we examined the behavior and synapse function in IQSEC2 knockout (KO) mice that we generated using CRIPSR/Cas9-mediated genome editing to solve the relevance between IQSEC2 deficiency and the pathophysiology of neurodevelopmental disorders. IQSEC2 KO mice exhibited autistic behaviors, such as overgrooming and social deficits. We identified that up-regulation of c-Fos expression in the medial prefrontal cortex (mPFC) induced by social stimulation was significantly attenuated in IQSEC2 KO mice. Whole cell electrophysiological recording identified that synaptic transmissions mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), N-methyl-D-aspartate receptor (NMDAR), and γ-aminobutyric acid receptor (GABAR) were significantly decreased in pyramidal neurons in layer 5 of the mPFC in IQSEC2 KO mice. Reexpression of IQSEC2 isoform 1 in the mPFC of IQSEC2 KO mice using adeno-associated virus (AAV) rescued both synaptic and social deficits, suggesting that impaired synaptic function in the mPFC is responsible for social deficits in IQSEC2 KO mice.
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Affiliation(s)
- Anuradha Mehta
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Yoshinori Shirai
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Emi Kouyama-Suzuki
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Mengyun Zhou
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Takahiro Yoshizawa
- Research Center for Advanced Science and Technology, Shinshu University, Matsumoto 390-8621, Japan;
| | - Toru Yanagawa
- Department of Oral and Maxillofacial Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan;
| | - Takuma Mori
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
- Department of NeuroHealth Innovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan
| | - Katsuhiko Tabuchi
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
- Department of NeuroHealth Innovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan
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Levy AP, Levy NS, Heyman E, Schertz M, Genizi J. Reduction in seizure burden in a child with a A350V IQSEC2 mutation using heat therapy with a Jacuzzi. Clin Case Rep 2021; 9:e04734. [PMID: 34484768 PMCID: PMC8405536 DOI: 10.1002/ccr3.4734] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 07/15/2021] [Accepted: 08/09/2021] [Indexed: 12/14/2022] Open
Abstract
A child with a A350V IQSEC2 missense mutation resulting in drug-resistant epilepsy stops having seizures when he has a fever. We demonstrate that raising the body temperature of the child using a commercial Jacuzzi dramatically reduces his seizures and appears to improve his social behavioral interactions.
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Affiliation(s)
- Andrew P Levy
- Technion Israel Institute of TechnologyTechnion Faculty of MedicineDepartment of BiochemistryHaifaIsrael
| | - Nina S Levy
- Technion Israel Institute of TechnologyTechnion Faculty of MedicineDepartment of BiochemistryHaifaIsrael
| | - Eli Heyman
- Department of Pediatric NeurologyAssaf Harofeh Medical Center and Tel Aviv UniversityTel AvivIsrael
| | - Mitchell Schertz
- Child Development and Pediatric Neurology ServiceMehudet North and Technion Israel Institute of TechnologyHaifaIsrael
| | - Jacob Genizi
- Bnai Zion Medical Center and Technion Israel Institute of TechnologyPediatric Neurology UnitHaifaIsrael
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Lopergolo D, Privitera F, Castello G, Lo Rizzo C, Mencarelli MA, Pinto AM, Ariani F, Currò A, Lamacchia V, Canitano R, Vaghi E, Ferrarini A, Baltodano GM, Lederer D, Van Maldergem L, Serrano M, Pineda M, Fons-Estupina MDC, Van Esch H, Breckpot J, Kumps C, Callewaert B, Mueller S, Ramelli GP, Armstrong J, Renieri A, Mari F. IQSEC2 disorder: A new disease entity or a Rett spectrum continuum? Clin Genet 2021; 99:462-474. [PMID: 33368194 DOI: 10.1111/cge.13908] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 12/12/2020] [Accepted: 12/22/2020] [Indexed: 12/27/2022]
Abstract
IQSEC2 mutations are associated with IQSEC2-related intellectual disability (ID). Phenotypic spectrum has been better defined in the last few years by the increasing number of reported cases although the genotype-phenotype relationship for IQSEC2 remains overall complex. As for IQSEC2-related ID a wide phenotypic diversity has been described in Rett syndrome (RTT). Several patients harboring IQSEC2 mutations present with clinical symptoms similar to RTT and some cases meet most of the criteria for classic RTT. With the aim of establishing a genotype-phenotype correlation, we collected data of 16 patients harboring IQSEC2 point mutations (15 of them previously unreported) and of five novel patients carrying CNVs encompassing IQSEC2. Most of our patients surprisingly shared a moderate-to-mild phenotype. The similarities in the clinical course between our mild cases and patients with milder forms of atypical RTT reinforce the hypothesis that also IQSEC2 mutated patients may lay under the wide clinical spectrum of RTT and thus IQSEC2 should be considered in the differential diagnosis. Our data confirm that position, type of variant and gender are crucial for IQSEC2-associated phenotype delineation.
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Affiliation(s)
- Diego Lopergolo
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | | | - Caterina Lo Rizzo
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | - Anna Maria Pinto
- Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Francesca Ariani
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Aurora Currò
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Vittoria Lamacchia
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Roberto Canitano
- Division of Child and Adolescent Neuropsychiatry, University Hospital of Siena, Siena, Italy
| | - Elisabetta Vaghi
- MAS Clinica Generale, Istituto Oncologico della Svizzera Italiana, Ospedale Regionale di Lugano, Italiano, Lugano, Switzerland
| | - Alessandra Ferrarini
- Chief Medical Genetics EOC, CSSI- Ospedale Regionale di Lugano, Italiano, Lugano, Switzerland
| | | | - Damien Lederer
- Department of Clinical Genetics, Centre for Human Genetics, Gosselies, Belgium
| | | | - Mercedes Serrano
- Pediatric Neurology Department, Hospital Sant Joan de Déu, Institut de Recerca, Barcelona, Spain.,U-703 CIBERER, Instituto de Salud Carlos III, Barcelona, Spain
| | - Mercè Pineda
- Department of Neuropediatria, Fundación Sant Joan de Déu, Barcelona, Spain
| | - Maria Del Carmen Fons-Estupina
- U-703 CIBERER, Instituto de Salud Carlos III, Barcelona, Spain.,Pediatric Neurology Department, Fetal-Neonatal Neurology Unit and Early Onset Epilepsy, Hospital Sant Joan de Déu, Institut de Recerca, Barcelona, Spain
| | - Hilde Van Esch
- Center for Human Genetics, University Hospitals Leuven, Leuven, Belgium
| | - Jeroen Breckpot
- Center for Human Genetics, University Hospitals Leuven, Leuven, Belgium
| | - Candy Kumps
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Bert Callewaert
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Sabrina Mueller
- Pediatric Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
| | - Gian Paolo Ramelli
- Pediatric Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland
| | - Judith Armstrong
- Genetics Department, Hospital Sant Joan de Deu, Institut Pediàtric de Recerca and CIBERER, Barcelona, Spain
| | - Alessandra Renieri
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Francesca Mari
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
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Nagabushana D, Chatterjee A, Kenchaiah R, Asranna A, Arunachal G, Mundlamuri RC. Response to Steroids in IQSEC2-Related Encephalopathy Presenting with Rett-Like Phenotype and Infantile Spasms. J Pediatr Genet 2020; 12:76-80. [PMID: 36684544 PMCID: PMC9848762 DOI: 10.1055/s-0040-1721371] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 10/14/2020] [Indexed: 01/25/2023]
Abstract
Introduction IQSEC2-related encephalopathy is an X-linked childhood neurodevelopmental disorder with intellectual disability, epilepsy, and autism. This disorder is caused by a mutation in the IQSEC2 gene, the product of which plays an important role in the development of the central nervous system. Case Report We describe the symptomatology, clinical course, and management of a 17-month-old male child with a novel IQSEC2 mutation. He presented with an atypical Rett syndrome phenotype with developmental delay, autistic features, midline stereotypies, microcephaly, hypotonia and epilepsy with multiple seizure types including late-onset infantile spasms. Spasms were followed by worsening of behavior and cognition, and regression of acquired milestones. Treatment with steroids led to control of spasms and improved attention, behavior and recovery of lost motor milestone. In the past 10 months following steroid therapy, child lags in development, remains autistic with no further seizure recurrence. Conclusion IQSEC2-related encephalopathy may present with Rett atypical phenotypes and childhood spasms. In resource-limited settings, steroids may be considered for spasm remission in IQSEC2-related epileptic encephalopathy.
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Affiliation(s)
- Divya Nagabushana
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Aparajita Chatterjee
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Raghavendra Kenchaiah
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Ajay Asranna
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Gautham Arunachal
- Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Ravindranadh Chowdary Mundlamuri
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India,Address for correspondence Ravindranadh Chowdary Mundlamuri, DM Department of Neurology, National Institute of Mental Health and NeurosciencesBengaluru 560029India
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10
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Sah M, Shore AN, Petri S, Kanber A, Yang M, Weston MC, Frankel WN. Altered excitatory transmission onto hippocampal interneurons in the IQSEC2 mouse model of X-linked neurodevelopmental disease. Neurobiol Dis 2020; 137:104758. [PMID: 31978606 DOI: 10.1016/j.nbd.2020.104758] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 12/16/2019] [Accepted: 01/20/2020] [Indexed: 02/01/2023] Open
Abstract
Mutations in the X-linked gene IQSEC2 are associated with multiple cases of epilepsy, epileptic encephalopathy, intellectual disability and autism spectrum disorder, the mechanistic understanding and successful treatment of which remain a significant challenge in IQSEC2 and related neurodevelopmental genetic diseases. To investigate disease etiology, we studied behaviors and synaptic function in IQSEC2 deficient mice. Hemizygous Iqsec2 null males exhibit growth deficits, hyperambulation and hyperanxiety phenotypes. Adult hemizygotes experience lethal spontaneous seizures, but paradoxically have a significantly increased threshold to electrically induced limbic seizures and relative resistance to chemically induced seizures. Although there are no gross defects in brain morphology, hemizygotes exhibit stark hippocampal reactive astrogliosis. Electrophysiological recordings of hippocampal neurons reveal increased excitatory drive specifically onto interneurons, and significant alterations in intrinsic electrical properties specific to the interneuron population. As they age, hemizygotes also develop an increased abundance of parvalbumin-positive interneurons in the hippocampus, neurons in which IQSEC2 is expressed in addition to the excitatory neurons. These findings point to a novel role of IQSEC2 in hippocampal interneuron synaptic function and development with implications for a class of intractable neurodevelopmental diseases.
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11
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Ibarluzea N, de la Hoz AB, Villate O, Llano I, Ocio I, Martí I, Guitart M, Gabau E, Andrade F, Gener B, Tejada MI. Targeted Next-Generation Sequencing in Patients with Suggestive X-Linked Intellectual Disability. Genes (Basel) 2020; 11:genes11010051. [PMID: 31906484 PMCID: PMC7017351 DOI: 10.3390/genes11010051] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/19/2019] [Accepted: 12/30/2019] [Indexed: 12/28/2022] Open
Abstract
X-linked intellectual disability (XLID) is known to contribute up to 10% of intellectual disability (ID) in males and could explain the increased ratio of affected males observed in patients with ID. Over the past decade, next-generation sequencing has clearly stimulated the gene discovery process and has become part of the diagnostic procedure. We have performed targeted next-generation sequencing of 82 XLID genes on 61 non-related male patients with suggestive non-syndromic XLID. These patients were initially referred to the molecular genetics laboratory to exclude Fragile X Syndrome. The cohort includes 47 male patients with suggestive X-linked family history of ID meaning that they had half-brothers or maternal cousins or uncles affected; and 14 male patients with ID and affected brothers whose mothers show skewed X-inactivation. Sequencing data analysis identified 17 candidate variants in 16 patients. Seven families could be re-contacted and variant segregation analysis of the respective eight candidate variants was performed: HUWE1, IQSEC2, MAOA, MED12, PHF8, SLC6A8, SLC9A6, and SYN1. Our results show the utility of targeted next-generation sequencing in unravelling the genetic origin of XLID, especially in retrospective cases. Variant segregation and additional studies like RNA sequencing and biochemical assays also helped in re-evaluating and further classifying the genetic variants found.
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Affiliation(s)
- Nekane Ibarluzea
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Ana Belén de la Hoz
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Olatz Villate
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - Isabel Llano
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - Intzane Ocio
- Department of Paediatric Neurology, Araba University Hospital, Osakidetza Basque Health Service, 01009 Gasteiz, Spain
| | - Itxaso Martí
- Department of Paediatric Neurology, Donostia University Hospital, Osakidetza Basque Health Service, 20014 Donostia, Spain
| | - Miriam Guitart
- Genetics Laboratory, Paediatric Unit, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, 08208 Sabadell, Spain
| | - Elisabeth Gabau
- Genetics Laboratory, Paediatric Unit, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, 08208 Sabadell, Spain
| | - Fernando Andrade
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Blanca Gener
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - María-Isabel Tejada
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
- Correspondence:
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12
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Choi MH, Yang JO, Min JS, Lee JJ, Jun SY, Lee YJ, Yoon JY, Jeon SJ, Byeon I, Kang JW, Kim NS. A Novel X-Linked Variant of IQSEC2 is Associated with Lennox-Gastaut Syndrome and Mild Intellectual Disability in Three Generations of a Korean Family. Genet Test Mol Biomarkers 2019; 24:54-58. [PMID: 31829726 DOI: 10.1089/gtmb.2019.0177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Aim: Lennox-Gastaut syndrome (LGS) is a severe type of childhood-onset epilepsy with multiple types of seizures, specific discharges on electroencephalography, and intellectual disability. However, LGS-related genes are largely unknown. To identify causative genes related to LGS, we collected and analyzed data from a three-generation Korean family in which one member had LGS and two had intellectual disability. Methods: Genomic DNAs were extracted from blood samples of all participants and used in whole-exome sequencing (WES). Genetic variants were detected by the Genome Analysis Toolkit and confirmed by Sanger sequencing. Variant pathogenicity was evaluated by prediction programs and the American College of Medical Genetics criteria. The LGS patient had generalized slow spike-and-wave discharges, multiple types of seizures, and developmental delay. Results: Analyses of the WES data from the family revealed a novel variant (c.1048G>A, p.Ala350Thr) in the IQ motif and Sec7 domain 2 (IQSEC2). This variant is within a highly evolutionarily conserved IQ-like motif, indicating a decrease in the calmodulin-binding capacity or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid transmission. The hemizygous variant in the male with LGS was a maternally inherited X-linked variant from the heterozygous maternal grandmother and mother, both of whom had intellectual disability. Conclusion: These findings indicate that the variant of IQSEC2 triggered both LGS and intellectual disability dependent on sex in this family. We report a novel X-linked inherited IQSEC2 variant for LGS and intellectual disability, which enhances the spectrum of variants in the IQ-like motif of IQSEC2.
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Affiliation(s)
- Min-Hyuk Choi
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Jin Ok Yang
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Ju-Sik Min
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Jeong-Ju Lee
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Soo-Young Jun
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Yong-Jae Lee
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Ji-Yong Yoon
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Su-Jin Jeon
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Iksu Byeon
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Joon-Won Kang
- Department of Pediatrics and Medical Science, Chungnam National University Hospital, College of Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Nam-Soon Kim
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
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13
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Rogers EJ, Jada R, Schragenheim-Rozales K, Sah M, Cortes M, Florence M, Levy NS, Moss R, Walikonis RS, Palty R, Shalgi R, Lichtman D, Kavushansky A, Gerges NZ, Kahn I, Umanah GKE, Levy AP. An IQSEC2 Mutation Associated With Intellectual Disability and Autism Results in Decreased Surface AMPA Receptors. Front Mol Neurosci 2019; 12:43. [PMID: 30842726 PMCID: PMC6391579 DOI: 10.3389/fnmol.2019.00043] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 02/01/2019] [Indexed: 12/30/2022] Open
Abstract
We have recently described an A350V mutation in IQSEC2 associated with intellectual disability, autism and epilepsy. We sought to understand the molecular pathophysiology of this mutation with the goal of developing targets for drug intervention. We demonstrate here that the A350V mutation results in interference with the binding of apocalmodulin to the IQ domain of IQSEC2. We further demonstrate that this mutation results in constitutive activation of the guanine nucleotide exchange factor (GEF) activity of IQSEC2 resulting in increased production of the active form of Arf6. In a CRISPR generated mouse model of the A350V IQSEC2 mutation, we demonstrate that the surface expression of GluA2 AMPA receptors in mouse hippocampal tissue was significantly reduced in A350V IQSEC2 mutant mice compared to wild type IQSEC2 mice and that there is a significant reduction in basal synaptic transmission in the hippocampus of A350V IQSEC2 mice compared to wild type IQSEC2 mice. Finally, the A350V IQSEC2 mice demonstrated increased activity, abnormal social behavior and learning as compared to wild type IQSEC2 mice. These findings suggest a model of how the A350V mutation in IQSEC2 may mediate disease with implications for targets for drug therapy. These studies provide a paradigm for a personalized approach to precision therapy for a disease that heretofore has no therapy.
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Affiliation(s)
- Eli J Rogers
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reem Jada
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | | | - Megha Sah
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Marisol Cortes
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Matthew Florence
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Nina S Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Rachel Moss
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Randall S Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Raz Palty
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reut Shalgi
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Daniela Lichtman
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Alexandra Kavushansky
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Nashaat Z Gerges
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Itamar Kahn
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - George K E Umanah
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
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14
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Mignot C, McMahon AC, Bar C, Campeau PM, Davidson C, Buratti J, Nava C, Jacquemont ML, Tallot M, Milh M, Edery P, Marzin P, Barcia G, Barnerias C, Besmond C, Bienvenu T, Bruel AL, Brunga L, Ceulemans B, Coubes C, Cristancho AG, Cunningham F, Dehouck MB, Donner EJ, Duban-Bedu B, Dubourg C, Gardella E, Gauthier J, Geneviève D, Gobin-Limballe S, Goldberg EM, Hagebeuk E, Hamdan FF, Hančárová M, Hubert L, Ioos C, Ichikawa S, Janssens S, Journel H, Kaminska A, Keren B, Koopmans M, Lacoste C, Laššuthová P, Lederer D, Lehalle D, Marjanovic D, Métreau J, Michaud JL, Miller K, Minassian BA, Morales J, Moutard ML, Munnich A, Ortiz-Gonzalez XR, Pinard JM, Prchalová D, Putoux A, Quelin C, Rosen AR, Roume J, Rossignol E, Simon MEH, Smol T, Shur N, Shelihan I, Štěrbová K, Vyhnálková E, Vilain C, Soblet J, Smits G, Yang SP, van der Smagt JJ, van Hasselt PM, van Kempen M, Weckhuysen S, Helbig I, Villard L, Héron D, Koeleman B, Møller RS, Lesca G, Helbig KL, Nabbout R, Verbeek NE, Depienne C. IQSEC2-related encephalopathy in males and females: a comparative study including 37 novel patients. Genet Med 2018; 21:837-849. [PMID: 30206421 PMCID: PMC6752297 DOI: 10.1038/s41436-018-0268-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/31/2018] [Indexed: 12/19/2022] Open
Abstract
Purpose Variants in IQSEC2, escaping X inactivation, cause X-linked intellectual disability with frequent epilepsy in males and females. We aimed to investigate sex-specific differences. Methods We collected the data of 37 unpublished patients (18 males and 19 females) with IQSEC2 pathogenic variants and 5 individuals with variants of unknown significance and reviewed published variants. We compared variant types and phenotypes in males and females and performed an analysis of IQSEC2 isoforms. Results IQSEC2 pathogenic variants mainly led to premature truncation and were scattered throughout the longest brain-specific isoform, encoding the synaptic IQSEC2/BRAG1 protein. Variants occurred de novo in females but were either de novo (2/3) or inherited (1/3) in males, with missense variants being predominantly inherited. Developmental delay and intellectual disability were overall more severe in males than in females. Likewise, seizures were more frequently observed and intractable, and started earlier in males than in females. No correlation was observed between the age at seizure onset and severity of intellectual disability or resistance to antiepileptic treatments. Conclusion This study provides a comprehensive overview of IQSEC2-related encephalopathy in males and females, and suggests that an accurate dosage of IQSEC2 at the synapse is crucial during normal brain development.
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Affiliation(s)
- Cyril Mignot
- INSERM, U 1127, CNRS UMR 7225, Sorbonne Universites, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle epiniere, ICM, Paris, France. .,APHP, Hôpital Pitie-Salpetriere, Departement de Genetique et de Cytogenetique; Centre de Reference Deficience Intellectuelle de Causes Rares; GRC UPMC «Deficience Intellectuelle et Autisme», Paris, France.
| | - Aoife C McMahon
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Claire Bar
- APHP, Reference Centre for Rare Epilepsies, Necker-Enfants Malades Hospital, Imagine Institute, Paris Descartes University, Paris, France.,INSERM U1163, Imagine Institute, Paris, France.,Paris Descartes University, Paris, France
| | - Philippe M Campeau
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and University of Montreal, Montreal, QC, Canada
| | - Claire Davidson
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Julien Buratti
- APHP, Hôpital Pitie-Salpetriere, Departement de Genetique et de Cytogenetique; Centre de Reference Deficience Intellectuelle de Causes Rares; GRC UPMC «Deficience Intellectuelle et Autisme», Paris, France
| | - Caroline Nava
- INSERM, U 1127, CNRS UMR 7225, Sorbonne Universites, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle epiniere, ICM, Paris, France.,APHP, Hôpital Pitie-Salpetriere, Departement de Genetique et de Cytogenetique; Centre de Reference Deficience Intellectuelle de Causes Rares; GRC UPMC «Deficience Intellectuelle et Autisme», Paris, France
| | | | - Marilyn Tallot
- CHU La Reunion-Groupe Hospitalier Sud Reunion, La Reunion, France
| | - Mathieu Milh
- APHM, Hôpital d'Enfants de La Timone, Service de Neurologie Pediatrique, centre de reference deficiences intellectuelles de cause rare, Marseille, France.,Aix Marseille University, INSERM, MMG, UMR-S 1251, Faculte de medecine, Marseille, France
| | - Patrick Edery
- Service de Genetique, Centre de Reference Anomalies du Developpement, Hospices Civils de Lyon, Bron, France.,INSERM U1028, CNRS UMR5292, Centre de Recherche en Neurosciences de Lyon, GENDEV Team, Universite Claude Bernard Lyon 1, Bron, France.,Claude Bernard Lyon I University, Lyon, France
| | - Pauline Marzin
- APHP, Hôpital Pitie-Salpetriere, Departement de Genetique et de Cytogenetique; Centre de Reference Deficience Intellectuelle de Causes Rares; GRC UPMC «Deficience Intellectuelle et Autisme», Paris, France
| | - Giulia Barcia
- INSERM U1163, Imagine Institute, Paris, France.,Paris Descartes University, Paris, France.,APHP, Service de genetique medicale, Necker-Enfants Malades Hospital, Imagine Institute, Paris Descartes University, Paris, France
| | - Christine Barnerias
- APHP, Unite fonctionnelle de Neurologie, Necker-Enfants Malades Hospital, Imagine Institute, Paris Descartes University, Paris, France
| | - Claude Besmond
- INSERM U1163, Imagine Institute, Paris, France.,Paris Descartes University, Paris, France
| | - Thierry Bienvenu
- APHP, Laboratoire de Genetique et Biologie Moleculaires, Hôpital Cochin, HUPC, Paris, France.,Universite Paris Descartes Paris, Institut de Psychiatrie et de Neurosciences de Paris, Inserm U894, Paris, France
| | - Ange-Line Bruel
- FHU-TRANSLAD, Universite de Bourgogne/CHU Dijon, Dijon, France.,INSERM UMR 1231 GAD team, Genetics of Developmental disorders, Universite de Bourgogne-Franche Comte, Dijon, France
| | - Ledia Brunga
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Berten Ceulemans
- Department of Pediatric Neurology, University Hospital and University of Antwerp, Antwerp, Belgium
| | - Christine Coubes
- Departement de Genetique Medicale, Maladies rares et Medecine Personnalisee, CHU de Montpellier, Montpellier, France
| | - Ana G Cristancho
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Fiona Cunningham
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | | | - Elizabeth J Donner
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Bénédicte Duban-Bedu
- Centre de Genetique Chromosomique, Hôpital St-Vincent-de-Paul, GHICL, Lille, France
| | - Christèle Dubourg
- CHU Rennes, Service de Genetique Moleculaire et Genomique, Rennes, France
| | - Elena Gardella
- Danish Epilepsy Centre Filadelfia, Dianalund, Denmark.,Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Julie Gauthier
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and University of Montreal, Montreal, QC, Canada
| | - David Geneviève
- Departement de Genetique Medicale, Maladies rares et Medecine Personnalisee, CHU de Montpellier, Montpellier, France.,INSERM U1183, Montpellier, France
| | - Stéphanie Gobin-Limballe
- APHP, Service de genetique medicale, Necker-Enfants Malades Hospital, Imagine Institute, Paris Descartes University, Paris, France
| | - Ethan M Goldberg
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Eveline Hagebeuk
- Stichting Epilepsie Instellingen Nederland, SEIN, Zwolle, The Netherlands
| | - Fadi F Hamdan
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and University of Montreal, Montreal, QC, Canada
| | - Miroslava Hančárová
- Department of Biology and Medical Genetics, Charles University 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic
| | - Laurence Hubert
- INSERM U1163, Imagine Institute, Paris, France.,Paris Descartes University, Paris, France
| | - Christine Ioos
- APHP, University Hospital of Paris ïle-de-France ouest, Raymond Poincare Hospital, Garches, France
| | - Shoji Ichikawa
- Department of Clinical Diagnostics, Ambry Genetics, Aliso Viejo, CA, USA
| | - Sandra Janssens
- Centre for Medical Genetics Ghent, Ghent University Hospital, C. Heymanslaan 10, Ghent, Belgium
| | - Hubert Journel
- Service de Genetique Medicale, Hôpital Chubert, Vannes, France
| | - Anna Kaminska
- APHP, Department of Clinical Neurophysiology, Necker-Enfants Malades Hospital, Paris, France
| | - Boris Keren
- APHP, Hôpital Pitie-Salpetriere, Departement de Genetique et de Cytogenetique; Centre de Reference Deficience Intellectuelle de Causes Rares; GRC UPMC «Deficience Intellectuelle et Autisme», Paris, France
| | - Marije Koopmans
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Caroline Lacoste
- Departement de Genetique Medicale, APHM, Hopital d'Enfants de La Timone, Marseille, France
| | - Petra Laššuthová
- Child Neurology Department, 2nd Faculty of Medicine, Charles University and Motol Hospital, Prague, Czech Republic
| | - Damien Lederer
- Centre de Genetique Humaine, Institut de Pathologie et de Genetique, Gosselies, Belgium
| | - Daphné Lehalle
- FHU-TRANSLAD, Universite de Bourgogne/CHU Dijon, Dijon, France.,Unite fonctionnelle de genetique clinique, Centre Hospitalier Intercommunal de Creteil, Creteil, France
| | | | - Julia Métreau
- APHP, Service de neurologie pediatrique, Hôpital Universitaire Bicetre, Le Kremlin-Bicetre, France
| | - Jacques L Michaud
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and University of Montreal, Montreal, QC, Canada
| | - Kathryn Miller
- Department of Pediatrics, Albany Medical Center, Albany, NY, USA
| | - Berge A Minassian
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Joannella Morales
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Marie-Laure Moutard
- APHP, Hôpital Trousseau, service de neuropediatrie, Paris, France.,Sorbonne Universite, GRC n°19, pathologies Congenitales du Cervelet-LeucoDystrophies, APHP, Hôpital Armand Trousseau, Paris, France
| | - Arnold Munnich
- INSERM U1163, Imagine Institute, Paris, France.,Paris Descartes University, Paris, France.,APHP, Service de genetique medicale, Necker-Enfants Malades Hospital, Imagine Institute, Paris Descartes University, Paris, France
| | | | - Jean-Marc Pinard
- Division of Neuropediatrics, CHU Raymond Poincare (APHP), Garches, France
| | - Darina Prchalová
- Department of Biology and Medical Genetics, Charles University 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic
| | - Audrey Putoux
- Service de Genetique, Centre de Reference Anomalies du Developpement, Hospices Civils de Lyon, Bron, France.,INSERM U1028, CNRS UMR5292, Centre de Recherche en Neurosciences de Lyon, GENDEV Team, Universite Claude Bernard Lyon 1, Bron, France.,Claude Bernard Lyon I University, Lyon, France
| | - Chloé Quelin
- Service de Genetique Medicale, CLAD Ouest CHU Hôpital Sud, Rennes, France
| | - Alyssa R Rosen
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Joelle Roume
- Unite de Genetique Medicale, Centre de Reference des Maladies rares du Developpement (AnD DI Rares), CHI Poissy-St Germain en Laye, Poissy, France
| | - Elsa Rossignol
- Departments of Pediatrics and Neurosciences, CHU Sainte-Justine and University of Montreal, Montreal, Canada
| | - Marleen E H Simon
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Thomas Smol
- Institut de Genetique Medicale, CHRU Lille, Universite de Lille, Lille, France
| | - Natasha Shur
- Department of Pediatrics, Albany Medical Center, Albany, NY, USA
| | - Ivan Shelihan
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and University of Montreal, Montreal, QC, Canada
| | - Katalin Štěrbová
- Child Neurology Department, 2nd Faculty of Medicine, Charles University and Motol Hospital, Prague, Czech Republic
| | - Emílie Vyhnálková
- Department of Biology and Medical Genetics, Charles University 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic
| | - Catheline Vilain
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium.,Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium.,Interuniversity Institute of Bioinformatics in Brussels, Universite Libre de Bruxelles, Brussels, Belgium
| | - Julie Soblet
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium.,Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium.,Interuniversity Institute of Bioinformatics in Brussels, Universite Libre de Bruxelles, Brussels, Belgium
| | - Guillaume Smits
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium.,Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Universite Libre de Bruxelles, Brussels, Belgium.,Interuniversity Institute of Bioinformatics in Brussels, Universite Libre de Bruxelles, Brussels, Belgium
| | - Samuel P Yang
- Clinical Genomics & Predictive Medicine, Providence Medical Group, Dayton, WA, USA
| | | | - Peter M van Hasselt
- Department of Metabolic Diseases, Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands
| | - Marjan van Kempen
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Sarah Weckhuysen
- Neurogenetics Group, Center of Molecular Neurology, VIB, Antwerp, Belgium.,Neurology Department, University Hospital Antwerp, Antwerp, Belgium
| | - Ingo Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Laurent Villard
- Aix Marseille University, INSERM, MMG, UMR-S 1251, Faculte de medecine, Marseille, France.,Departement de Genetique Medicale, APHM, Hopital d'Enfants de La Timone, Marseille, France
| | - Delphine Héron
- APHP, Hôpital Pitie-Salpetriere, Departement de Genetique et de Cytogenetique; Centre de Reference Deficience Intellectuelle de Causes Rares; GRC UPMC «Deficience Intellectuelle et Autisme», Paris, France
| | - Bobby Koeleman
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Rikke S Møller
- CHU Rennes, Service de Genetique Moleculaire et Genomique, Rennes, France.,Danish Epilepsy Centre Filadelfia, Dianalund, Denmark
| | - Gaetan Lesca
- Service de Genetique, Centre de Reference Anomalies du Developpement, Hospices Civils de Lyon, Bron, France.,INSERM U1028, CNRS UMR5292, Centre de Recherche en Neurosciences de Lyon, GENDEV Team, Universite Claude Bernard Lyon 1, Bron, France.,Claude Bernard Lyon I University, Lyon, France
| | - Katherine L Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Rima Nabbout
- APHP, Reference Centre for Rare Epilepsies, Necker-Enfants Malades Hospital, Imagine Institute, Paris Descartes University, Paris, France.,INSERM U1163, Imagine Institute, Paris, France.,Paris Descartes University, Paris, France
| | - Nienke E Verbeek
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Christel Depienne
- INSERM, U 1127, CNRS UMR 7225, Sorbonne Universites, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle epiniere, ICM, Paris, France. .,IGBMC, CNRS UMR 7104/INSERM U964/Universite de Strasbourg, Illkirch, France. .,Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
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15
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Zipper R, Baine SD, Genizi J, Maoz H, Levy NS, Levy AP. Developmental progression of intellectual disability, autism, and epilepsy in a child with an IQSEC2 gene mutation. Clin Case Rep 2017; 5:1639-1643. [PMID: 29026562 PMCID: PMC5628232 DOI: 10.1002/ccr3.1139] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/27/2017] [Indexed: 01/17/2023] Open
Abstract
The neurodevelopmental progression of a school‐aged child with a spontaneous IQSEC2 mutation has demonstrated apparent regression of milestones and language. Seizures associated with the disorder have been refractory to medical treatment. Late treatment of autism in this child has led to improved social skills.
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Affiliation(s)
- Rachelle Zipper
- Technion Faculty of Medicine Technion Israel Institute of Technology Haifa Israel
| | - Sherri D Baine
- Department of Pediatrics North York General Hospital University of Toronto Toronto Ontario Canada
| | - Jacob Genizi
- Technion Faculty of Medicine Technion Israel Institute of Technology Haifa Israel.,Pediatric Neurology Unit Bnai Zion Medical Center Haifa Israel
| | - Hen Maoz
- Kiryat Shmona Regional Unit for Child Development Kiryat Shmona Israel
| | - Nina S Levy
- Technion Faculty of Medicine Technion Israel Institute of Technology Haifa Israel
| | - Andrew P Levy
- Technion Faculty of Medicine Technion Israel Institute of Technology Haifa Israel
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16
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Helm BM, Powis Z, Prada CE, Casasbuenas-Alarcon OL, Balmakund T, Schaefer GB, Kahler SG, Kaylor J, Winter S, Zarate YA, Schrier Vergano SA. The role of IQSEC2 in syndromic intellectual disability: Narrowing the diagnostic odyssey. Am J Med Genet A 2017; 173:2814-2820. [PMID: 28815955 DOI: 10.1002/ajmg.a.38404] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 07/03/2017] [Accepted: 07/20/2017] [Indexed: 01/16/2023]
Abstract
While X-linked intellectual disability (XLID) syndromes pose a diagnostic challenge for clinicians, an increasing number of recognized disorders and their genetic etiologies are providing answers for patients and their families. The availability of clinical exome sequencing is broadening the ability to identify mutations in genes previously unrecognized as causing XLID. In recent years, the IQSEC2 gene, located at Xp11.22, has emerged as the cause of multiple cases of both nonsyndromic and syndromic XLID. Herein we present a case series of six individuals (five males, one female) with intellectual disability and seizures found to have alterations in IQSEC2. In all cases, the diagnostic odyssey was extensive and expensive, often including invasive testing such as muscle biopsies, before ultimately reaching the diagnosis. We report these cases to demonstrate the exhaustive work-up prior to finding the changes in IQSEC2 gene, recommend that this gene be considered earlier in the diagnostic evaluation of individuals with global developmental delay, microcephaly, and severe, intractable epilepsy, and support the use of intellectual disability panels including IQSEC2 in the first-line evaluation of these patients.
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Affiliation(s)
- Benjamin M Helm
- Department of Medical and Molecular Genetics, Indiana University School of Medicine and Riley Hospital for Children at IU Health, Indianapolis, Indiana
| | - Zoe Powis
- Ambry Genetics, Department of Clinical Genomics, Aliso Viejo, California
| | - Carlos E Prada
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio.,Centro de Medicina Genomica y Metabolismo, Fundación Cardiovascular de Colombia, Floridablanca, Colombia
| | | | - Tonya Balmakund
- Division of Neurology, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - G B Schaefer
- Section of Genetics and Metabolism, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Stephen G Kahler
- Section of Genetics and Metabolism, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Julie Kaylor
- Arkansas Children's Hospital, Little Rock, Arkansas
| | - Susan Winter
- Valley Children's Hospital, Department of Genetic Medicine and Metabolism, Madera, California
| | - Yuri A Zarate
- Section of Genetics and Metabolism, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Samantha A Schrier Vergano
- Division of Medical Genetics and Metabolism, Children's Hospital of The King's Daughters, Norfolk, Virginia.,Department of Pediatrics, Eastern Virginia Medical School, Norfolk, Virginia
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17
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Kalscheuer VM, James VM, Himelright ML, Long P, Oegema R, Jensen C, Bienek M, Hu H, Haas SA, Topf M, Hoogeboom AJM, Harvey K, Walikonis R, Harvey RJ. Novel Missense Mutation A789V in IQSEC2 Underlies X-Linked Intellectual Disability in the MRX78 Family. Front Mol Neurosci 2016; 8:85. [PMID: 26793055 PMCID: PMC4707274 DOI: 10.3389/fnmol.2015.00085] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 12/14/2015] [Indexed: 12/04/2022] Open
Abstract
Disease gene discovery in neurodevelopmental disorders, including X-linked intellectual disability (XLID) has recently been accelerated by next-generation DNA sequencing approaches. To date, more than 100 human X chromosome genes involved in neuronal signaling pathways and networks implicated in cognitive function have been identified. Despite these advances, the mutations underlying disease in a large number of XLID families remained unresolved. We report the resolution of MRX78, a large family with six affected males and seven affected females, showing X-linked inheritance. Although a previous linkage study had mapped the locus to the short arm of chromosome X (Xp11.4-p11.23), this region contained too many candidate genes to be analyzed using conventional approaches. However, our X-chromosome exome resequencing, bioinformatics analysis and inheritance testing revealed a missense mutation (c.C2366T, p.A789V) in IQSEC2, encoding a neuronal GDP-GTP exchange factor for Arf family GTPases (ArfGEF) previously implicated in XLID. Molecular modeling of IQSEC2 revealed that the A789V substitution results in the insertion of a larger side-chain into a hydrophobic pocket in the catalytic Sec7 domain of IQSEC2. The A789V change is predicted to result in numerous clashes with adjacent amino acids and disruption of local folding of the Sec7 domain. Consistent with this finding, functional assays revealed that recombinant IQSEC2A789V was not able to catalyze GDP-GTP exchange on Arf6 as efficiently as wild-type IQSEC2. Taken together, these results strongly suggest that the A789V mutation in IQSEC2 is the underlying cause of XLID in the MRX78 family.
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Affiliation(s)
- Vera M Kalscheuer
- Department of Human Molecular Genetics, Max Planck Institute for Molecular GeneticsBerlin, Germany; Research Group Development and Disease, Max Planck Institute for Molecular GeneticsBerlin, Germany
| | | | - Miranda L Himelright
- Department of Physiology and Neurobiology, University of Connecticut Storrs, CT, USA
| | - Philip Long
- Department of Pharmacology, UCL School of Pharmacy London, UK
| | - Renske Oegema
- Department of Clinical Genetics, Erasmus MC University Medical Center Rotterdam Rotterdam, Netherlands
| | - Corinna Jensen
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics Berlin, Germany
| | - Melanie Bienek
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics Berlin, Germany
| | - Hao Hu
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics Berlin, Germany
| | - Stefan A Haas
- Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics Berlin, Germany
| | - Maya Topf
- Department of Biological Sciences, Institute for Structural and Molecular Biology, Birkbeck College London, UK
| | - A Jeannette M Hoogeboom
- Department of Clinical Genetics, Erasmus MC University Medical Center Rotterdam Rotterdam, Netherlands
| | - Kirsten Harvey
- Department of Pharmacology, UCL School of Pharmacy London, UK
| | - Randall Walikonis
- Department of Physiology and Neurobiology, University of Connecticut Storrs, CT, USA
| | - Robert J Harvey
- Department of Pharmacology, UCL School of Pharmacy London, UK
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18
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Fieremans N, Van Esch H, de Ravel T, Van Driessche J, Belet S, Bauters M, Froyen G. Microdeletion of the escape genes KDM5C and IQSEC2 in a girl with severe intellectual disability and autistic features. Eur J Med Genet 2015; 58:324-7. [PMID: 25858702 DOI: 10.1016/j.ejmg.2015.03.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/23/2015] [Indexed: 10/23/2022]
Abstract
Intellectual disability (ID) is a very heterogeneous disorder with over 100 ID genes located on the X chromosome alone. Of these, KDM5C and IQSEC2 are located adjacent to each other at the Xp11.22 locus. While mutations in either of these genes are associated with severe ID in males, female carriers are mostly unaffected. Here, we report on a female patient with severe ID and autistic features carrying a de novo 0.4 Mb deletion containing six coding genes including KDM5C and IQSEC2. X-inactivation analysis revealed skewing in a lymphocyte-derived cell line from this patient with preferential inactivation of the mutant X chromosome. As the brain-expressed KDM5C and IQSEC2 genes escape X-inactivation, deletion of these alleles could still be detrimental despite skewing of X-inactivation. Indeed, mutations in either of both genes have been reported in a few female ID patients. Expression analysis in the patients' cell line revealed decreased KDM5C mRNA levels compared to female controls. IQSEC2 levels could not be compared due to very low expression in blood. Overall, our data suggest that heterozygous loss-of-function of the escape genes KDM5C and/or IQSEC2 can contribute to severe ID in female patients and should be taken into account in diagnostics.
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Affiliation(s)
- Nathalie Fieremans
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium; Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Hilde Van Esch
- Department of Human Genetics, University Hospitals Leuven, Leuven, Belgium
| | - Thomy de Ravel
- Department of Human Genetics, University Hospitals Leuven, Leuven, Belgium
| | | | - Stefanie Belet
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium; Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Marijke Bauters
- Human Genome Laboratory, VIB Center for the Biology of Disease, Leuven, Belgium; Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Guy Froyen
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, Belgium.
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