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Bosch E, Güse E, Kirchner P, Winterpacht A, Walther M, Alders M, Kerkhof J, Ekici AB, Sticht H, Sadikovic B, Reis A, Vasileiou G. The missing link: ARID1B non-truncating variants causing Coffin-Siris syndrome due to protein aggregation. Hum Genet 2024; 143:965-978. [PMID: 39028335 PMCID: PMC11303441 DOI: 10.1007/s00439-024-02688-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 07/07/2024] [Indexed: 07/20/2024]
Abstract
ARID1B is the most frequently mutated gene in Coffin-Siris syndrome (CSS). To date, the vast majority of causative variants reported in ARID1B are truncating, leading to nonsense-mediated mRNA decay. In the absence of experimental data, only few ARID1B amino acid substitutions have been classified as pathogenic, mainly based on clinical data and their de novo occurrence, while most others are currently interpreted as variants of unknown significance. The present study substantiates the pathogenesis of ARID1B non-truncating/NMD-escaping variants located in the SMARCA4-interacting EHD2 and DNA-binding ARID domains. Overexpression assays in cell lines revealed that the majority of EHD2 variants lead to protein misfolding and formation of cytoplasmic aggresomes surrounded by vimentin cage-like structures and co-localizing with the microtubule organisation center. ARID domain variants exhibited not only aggresomes, but also nuclear aggregates, demonstrating robust pathological effects. Protein levels were not compromised, as shown by quantitative western blot analysis. In silico structural analysis predicted the exposure of amylogenic segments in both domains due to the nearby variants, likely causing this aggregation. Genome-wide transcriptome and methylation analysis in affected individuals revealed expression and methylome patterns consistent with those of the pathogenic haploinsufficiency ARID1B alterations in CSS cases. These results further support pathogenicity and indicate two approaches for disambiguation of such variants in everyday practice. The few affected individuals harbouring EHD2 non-truncating variants described to date exhibit mild CSS clinical traits. In summary, this study paves the way for the re-evaluation of previously unclear ARID1B non-truncating variants and opens a new era in CSS genetic diagnosis.
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Affiliation(s)
- Elisabeth Bosch
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Esther Güse
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Philipp Kirchner
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Andreas Winterpacht
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Mona Walther
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Marielle Alders
- Amsterdam University Medical Center, University of Amsterdam, Department of Human Genetics, Amsterdam Reproduction and Development Research Institute, Amsterdam, The Netherlands
| | - Jennifer Kerkhof
- Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, ON, Canada
| | - Arif B Ekici
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Bekim Sadikovic
- Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, ON, Canada
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
| | - André Reis
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany
- Centre for Rare Diseases Erlangen (ZSEER), Universitätsklinikum Erlangen, Erlangen, Germany
| | - Georgia Vasileiou
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054, Erlangen, Germany.
- Centre for Rare Diseases Erlangen (ZSEER), Universitätsklinikum Erlangen, Erlangen, Germany.
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Margot H, Pizano A, Amestoy A, Lacombe D, Berges C, Beneteau C, Innes AM. Investigations of an individual with a Marfanoid habitus, mild intellectual disability, and severe social anxiety identifies PCDHGA5 as a candidate neurodevelopmental disorder gene. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2024:e32087. [PMID: 38591859 DOI: 10.1002/ajmg.c.32087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 03/23/2024] [Accepted: 03/31/2024] [Indexed: 04/10/2024]
Abstract
Marfanoid habitus and intellectual disability (MHID) co-occur in multiple neurodevelopmental disorders (NDD). Among those, Lujan-Fryns, an X-linked genetic disorder associated with variants in MED12 was the first such syndrome identified. Accurate molecular diagnosis for these MHID syndromes remains a challenge due to significant clinical and genetic heterogeneity. We present a case report of a 20-year-old male patient with MHID and severe social anxiety. A comprehensive clinical evaluation, including morphotype assessment, cognitive, and psychometric and genetic testing, was conducted to provide a detailed understanding of the patient's complex clinical presentation. Psychometric assessments revealed severe social anxiety and various cognitive and emotional challenges. Despite some autism-like symptoms, the patient's clinical presentation was more aligned with mild intellectual disability. Exome sequencing was inconclusive but identified a heterozygous de novo missense variant in the PCDHGA5 gene. This gene is not known in human pathology yet, but we also report a second patient with a syndromic neurodevelopmental disorder and a rare de novo variant which leads us to propose this as a candidate gene. Our findings emphasize the importance of multidisciplinary approach in the diagnosis and management of MHID. This case report underscores the need for objective clinical evaluations and standardized tools to better understand the complex clinical profiles of patients with NDDs. The identification of novel PCDHGA5 gene variants adds this gene's candidacy to the genetic landscape of MHID-NDD, warranting further investigation to determine its potential contribution.
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Affiliation(s)
- Henri Margot
- Univ. Bordeaux, MRGM INSERM U1211, CHU de Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - Adrien Pizano
- Aquitaine Autism Resources Centre, Centre Hospitalier Charles-Perrens, University Pole of Child and Adolescent Psychiatry, Bordeaux, France
| | - Anouck Amestoy
- Aquitaine Autism Resources Centre, Centre Hospitalier Charles-Perrens, University Pole of Child and Adolescent Psychiatry, Bordeaux, France
| | - Didier Lacombe
- Univ. Bordeaux, MRGM INSERM U1211, CHU de Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - Camille Berges
- Univ. Bordeaux, MRGM INSERM U1211, CHU de Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - Claire Beneteau
- Univ. Bordeaux, MRGM INSERM U1211, CHU de Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - A Micheil Innes
- Department of Medical Genetics and Pediatrics and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
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3
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Bhat S, Rousseau J, Michaud C, Lourenço CM, Stoler JM, Louie RJ, Clarkson LK, Lichty A, Koboldt DC, Reshmi SC, Sisodiya SM, Hoytema van Konijnenburg EMM, Koop K, van Hasselt PM, Démurger F, Dubourg C, Sullivan BR, Hughes SS, Thiffault I, Tremblay ES, Accogli A, Srour M, Blunck R, Campeau PM. Mono-allelic KCNB2 variants lead to a neurodevelopmental syndrome caused by altered channel inactivation. Am J Hum Genet 2024; 111:761-777. [PMID: 38503299 PMCID: PMC11023922 DOI: 10.1016/j.ajhg.2024.02.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 02/23/2024] [Accepted: 02/25/2024] [Indexed: 03/21/2024] Open
Abstract
Ion channels mediate voltage fluxes or action potentials that are central to the functioning of excitable cells such as neurons. The KCNB family of voltage-gated potassium channels (Kv) consists of two members (KCNB1 and KCNB2) encoded by KCNB1 and KCNB2, respectively. These channels are major contributors to delayed rectifier potassium currents arising from the neuronal soma which modulate overall excitability of neurons. In this study, we identified several mono-allelic pathogenic missense variants in KCNB2, in individuals with a neurodevelopmental syndrome with epilepsy and autism in some individuals. Recurrent dysmorphisms included a broad forehead, synophrys, and digital anomalies. Additionally, we selected three variants where genetic transmission has not been assessed, from two epilepsy studies, for inclusion in our experiments. We characterized channel properties of these variants by expressing them in oocytes of Xenopus laevis and conducting cut-open oocyte voltage clamp electrophysiology. Our datasets indicate no significant change in absolute conductance and conductance-voltage relationships of most disease variants as compared to wild type (WT), when expressed either alone or co-expressed with WT-KCNB2. However, variants c.1141A>G (p.Thr381Ala) and c.641C>T (p.Thr214Met) show complete abrogation of currents when expressed alone with the former exhibiting a left shift in activation midpoint when expressed alone or with WT-KCNB2. The variants we studied, nevertheless, show collective features of increased inactivation shifted to hyperpolarized potentials. We suggest that the effects of the variants on channel inactivation result in hyper-excitability of neurons, which contributes to disease manifestations.
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Affiliation(s)
- Shreyas Bhat
- Center for Interdisciplinary Research on Brain and Learning (CIRCA), Department of Physics and Department of Pharmacology and Physiology, Université de Montréal, Montréal, QC, Canada
| | - Justine Rousseau
- Centre de Recherche Du Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC H3T 1C5, Canada
| | - Coralie Michaud
- Centre de Recherche Du Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC H3T 1C5, Canada
| | | | - Joan M Stoler
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | | | | | - Angie Lichty
- Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Daniel C Koboldt
- Steve and Cindy Rasmussen Institute for Genomic Medicine at Nationwide Children's Hospital, Columbus, OH, USA
| | - Shalini C Reshmi
- Steve and Cindy Rasmussen Institute for Genomic Medicine at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London WC1N 3BG, UK
| | | | - Klaas Koop
- Department of Metabolic Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Peter M van Hasselt
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - Christèle Dubourg
- Department of Molecular Genetics and Genomics, Rennes University Hospital, Rennes, France; Université de Rennes, CNRS, IGDR, UMR 6290 Rennes, France
| | - Bonnie R Sullivan
- Division of Clinical Genetics, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Susan S Hughes
- Division of Clinical Genetics, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Isabelle Thiffault
- Departments of Pediatrics and of Pathology and Laboratory Medicine, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Elisabeth Simard Tremblay
- Department of Neurology and Neurosurgery, McGill University Health Centre, Montréal, QC, Canada; Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montréal, QC, Canada
| | - Andrea Accogli
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Centre, Montréal, QC, Canada; Department of Human Genetics, Faculty of Medicine, McGill University, Montral, QC H3A 1B1, Canada
| | - Myriam Srour
- Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montréal, QC, Canada; Department of Human Genetics, Faculty of Medicine, McGill University, Montral, QC H3A 1B1, Canada
| | - Rikard Blunck
- Center for Interdisciplinary Research on Brain and Learning (CIRCA), Department of Physics and Department of Pharmacology and Physiology, Université de Montréal, Montréal, QC, Canada.
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Fahey L, Ali D, Donohoe G, Ó Broin P, Morris DW. Genes positively regulated by Mef2c in cortical neurons are enriched for common genetic variation associated with IQ and educational attainment. Hum Mol Genet 2023; 32:3194-3203. [PMID: 37672226 PMCID: PMC10630234 DOI: 10.1093/hmg/ddad142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 09/07/2023] Open
Abstract
The myocyte enhancer factor 2 C (MEF2C) gene encodes a transcription factor important for neurogenesis and synapse development and contains common variants associated with intelligence (IQ) and educational attainment (EA). Here, we took gene expression data from the mouse cortex of a Mef2c mouse model with a heterozygous DNA binding-deficient mutation of Mef2c (Mef2c-het) and combined these data with MEF2C ChIP-seq data from cortical neurons and single-cell data from the mouse brain. This enabled us to create a set of genes that were differentially regulated in Mef2c-het mice, represented direct target genes of MEF2C and had elevated in expression in cortical neurons. We found this gene-set to be enriched for genes containing common genetic variation associated with IQ and EA. Genes within this gene-set that were down-regulated, i.e. have reduced expression in Mef2c-het mice versus controls, were specifically significantly enriched for both EA and IQ associated genes. These down-regulated genes were enriched for functionality in the adenylyl cyclase signalling system, which is known to positively regulate synaptic transmission and has been linked to learning and memory. Within the adenylyl cyclase signalling system, three genes regulated by MEF2C, CRHR1, RGS6, and GABRG3, are associated at genome-wide significant levels with IQ and/or EA. Our results indicate that genetic variation in MEF2C and its direct target genes within cortical neurons contribute to variance in cognition within the general population, and the molecular mechanisms involved include the adenylyl cyclase signalling system's role in synaptic function.
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Affiliation(s)
- Laura Fahey
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
- Discipline of Bioinformatics, School of Mathematical and Statistical Sciences, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Deema Ali
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Gary Donohoe
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Pilib Ó Broin
- Discipline of Bioinformatics, School of Mathematical and Statistical Sciences, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Derek W Morris
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
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Olivati C, Favilla BP, Freitas EL, Santos B, Melaragno MI, Meloni VA, Piazzon F. Allan-Herndon-Dudley syndrome in a female patient and related mechanisms. Mol Genet Metab Rep 2022; 31:100879. [PMID: 35782622 PMCID: PMC9248228 DOI: 10.1016/j.ymgmr.2022.100879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 11/30/2022] Open
Abstract
Allan-Herndon-Dudley syndrome (AHDS) is characterized by neuropsychomotor developmental delay/intellectual disability, neurological impairment with a movement disorder, and an abnormal thyroid hormone profile. This disease is an X-linked disorder that mainly affects men. We described a female patient with a de novo variant in the SLC16A2 gene, a milder AHDS phenotype, and a skewed X chromosome inactivation profile. We discuss the mechanisms associated with the expression of the phenotypic characteristics in female patients, including SLC16A2 gene variants and cytogenomic alterations, as well as preferential inactivation of the normal X chromosome.
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Affiliation(s)
- Caroline Olivati
- Rare Rosy Clinic, São Paulo, Brazil
- Fleury Medicina e Saúde, São Paulo, Brazil
- Corresponding author at: Rare Rosy Clinic, Rua Borges Lagoa, 1080, CEP 04038-020 São Paulo, SP, Brazil.
| | - Bianca Pereira Favilla
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil
| | | | | | - Maria Isabel Melaragno
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Vera Ayres Meloni
- Rare Rosy Clinic, São Paulo, Brazil
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Flavia Piazzon
- Rare Rosy Clinic, São Paulo, Brazil
- Neuromuscular Reference Center, Department of Pediatrics, University Hospital Liège & University of Liège, Belgium
- Neurometabolic Unit, University of São Paulo, São Paulo, Brazil
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Comprehensive Genetic Testing for Pediatric Hypertrophic Cardiomyopathy Reveals Clinical Management Opportunities and Syndromic Conditions. Pediatr Cardiol 2022; 43:616-623. [PMID: 34714385 PMCID: PMC8554517 DOI: 10.1007/s00246-021-02764-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) has historically been diagnosed phenotypically. Through genetic testing, identification of a molecular diagnosis (MolDx) is increasingly common but the impact on pediatric patients is unknown. This was a retrospective study of next-generation sequencing data for 602 pediatric patients with a clinician-reported history of HCM. Diagnostic yield was stratified by gene and self-reported race/ethnicity. A MolDx of HCM was identified in 242 (40%) individuals. Sarcomeric genes were the highest yielding, but pathogenic and/or likely pathogenic (P/LP) variants in syndromic genes were found in 36% of individuals with a MolDx, often in patients without documented clinical suspicion for a genetic syndrome. Among all MolDx, 73% were in genes with established clinical management recommendations and 2.9% were in genes that conferred eligibility for clinical trial enrollment. Black patients were the least likely to receive a MolDx. In the current era, genetic testing can impact management of HCM, beyond diagnostics or prognostics, through disease-specific guidelines or clinical trial eligibility. Genetic testing frequently can help identify syndromes in patients for whom syndromes may not be suspected. These findings highlight the importance of pursuing broad genetic testing, independent of suspicion based on phenotype. Lower rates of MolDx in Black patients may contribute to health inequities. Further research is needed evaluating the genetics of HCM in underrepresented/underserved populations. Additionally, research related to the impact of genetic testing on clinical management of other diseases is warranted.
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Larrigan S, Shah S, Fernandes A, Mattar P. Chromatin Remodeling in the Brain-a NuRDevelopmental Odyssey. Int J Mol Sci 2021; 22:ijms22094768. [PMID: 33946340 PMCID: PMC8125410 DOI: 10.3390/ijms22094768] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 04/27/2021] [Indexed: 01/07/2023] Open
Abstract
During brain development, the genome must be repeatedly reconfigured in order to facilitate neuronal and glial differentiation. A host of chromatin remodeling complexes facilitates this process. At the genetic level, the non-redundancy of these complexes suggests that neurodevelopment may require a lexicon of remodelers with different specificities and activities. Here, we focus on the nucleosome remodeling and deacetylase (NuRD) complex. We review NuRD biochemistry, genetics, and functions in neural progenitors and neurons.
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Affiliation(s)
- Sarah Larrigan
- Department of Cell and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (S.L.); (S.S.); (A.F.)
- Ottawa Health Research Institute (OHRI), Ottawa, ON K1H 8L6, Canada
| | - Sujay Shah
- Department of Cell and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (S.L.); (S.S.); (A.F.)
- Ottawa Health Research Institute (OHRI), Ottawa, ON K1H 8L6, Canada
| | - Alex Fernandes
- Department of Cell and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (S.L.); (S.S.); (A.F.)
- Ottawa Health Research Institute (OHRI), Ottawa, ON K1H 8L6, Canada
| | - Pierre Mattar
- Department of Cell and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; (S.L.); (S.S.); (A.F.)
- Ottawa Health Research Institute (OHRI), Ottawa, ON K1H 8L6, Canada
- Correspondence:
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