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Rühl P, Nair AG, Gawande N, Dehiwalage SNCW, Münster L, Schönherr R, Heinemann SH. An Ultrasensitive Genetically Encoded Voltage Indicator Uncovers the Electrical Activity of Non-Excitable Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307938. [PMID: 38526185 PMCID: PMC11132041 DOI: 10.1002/advs.202307938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 02/10/2024] [Indexed: 03/26/2024]
Abstract
Most animal cell types are classified as non-excitable because they do not generate action potentials observed in excitable cells, such as neurons and muscle cells. Thus, resolving voltage signals in non-excitable cells demands sensors with exceptionally high voltage sensitivity. In this study, the ultrabright, ultrasensitive, and calibratable genetically encoded voltage sensor rEstus is developed using structure-guided engineering. rEstus is most sensitive in the resting voltage range of non-excitable cells and offers a 3.6-fold improvement in brightness change for fast voltage spikes over its precursor ASAP3. Using rEstus, it is uncovered that the membrane voltage in several non-excitable cell lines (A375, HEK293T, MCF7) undergoes spontaneous endogenous alterations on a second to millisecond timescale. Correlation analysis of these optically recorded voltage alterations provides a direct, real-time readout of electrical cell-cell coupling, showing that visually connected A375 and HEK293T cells are also largely electrically connected, while MCF7 cells are only weakly coupled. The presented work provides enhanced tools and methods for non-invasive voltage imaging in living cells and demonstrates that spontaneous endogenous membrane voltage alterations are not limited to excitable cells but also occur in a variety of non-excitable cell types.
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Affiliation(s)
- Philipp Rühl
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, D-07745, Jena, Germany
| | - Anagha G Nair
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, D-07745, Jena, Germany
| | - Namrata Gawande
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, D-07745, Jena, Germany
| | - Sassrika N C W Dehiwalage
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, D-07745, Jena, Germany
| | - Lukas Münster
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, D-07745, Jena, Germany
| | - Roland Schönherr
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, D-07745, Jena, Germany
| | - Stefan H Heinemann
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital, D-07745, Jena, Germany
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Garg R, Sullivan J, Blair D, Wallerstein R. KCNK4-related channelopathy causing a neurodevelopmental syndrome. BMJ Case Rep 2023; 16:e253410. [PMID: 37931962 PMCID: PMC10632805 DOI: 10.1136/bcr-2022-253410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023] Open
Affiliation(s)
- Ria Garg
- Medical Genetics, University of California San Francisco, San Francisco, California, USA
| | - Joseph Sullivan
- Pediatric Neurology, University of California San Francisco, San Francisco, California, USA
| | - David Blair
- Medical Genetics, University of California San Francisco, San Francisco, California, USA
| | - Robert Wallerstein
- Medical Genetics, University of California San Francisco, San Francisco, California, USA
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3
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Cioclu MC, Mosca I, Ambrosino P, Puzo D, Bayat A, Wortmann SB, Koch J, Strehlow V, Shirai K, Matsumoto N, Sanders SJ, Michaud V, Legendre M, Riva A, Striano P, Muhle H, Pendziwiat M, Lesca G, Mangano GD, Nardello R, Lemke JR, Møller RS, Soldovieri MV, Rubboli G, Taglialatela M. KCNT2-Related Disorders: Phenotypes, Functional, and Pharmacological Properties. Ann Neurol 2023; 94:332-349. [PMID: 37062836 DOI: 10.1002/ana.26662] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 04/10/2023] [Accepted: 04/14/2023] [Indexed: 04/18/2023]
Abstract
OBJECTIVE Pathogenic variants in KCNT2 are rare causes of developmental epileptic encephalopathy (DEE). We herein describe the phenotypic and genetic features of patients with KCNT2-related DEE, and the in vitro functional and pharmacological properties of KCNT2 channels carrying 14 novel or previously untested variants. METHODS Twenty-five patients harboring KCNT2 variants were investigated: 12 were identified through an international collaborative network, 13 were retrieved from the literature. Clinical data were collected and included in a standardized phenotyping sheet. Novel variants were detected using exome sequencing and classified using ACMG criteria. Functional and pharmacological studies were performed by whole-cell electrophysiology in HEK-293 and SH-SY5Y cells. RESULTS The phenotypic spectrum encompassed: (a) intellectual disability/developmental delay (21/22 individuals with available information), ranging from mild to severe/profound; (b) epilepsy (15/25); (c) neurological impairment, with altered muscle tone (14/22); (d) dysmorphisms (13/20). Nineteen pathogenic KCNT2 variants were found (9 new, 10 reported previously): 16 missense, 1 in-frame deletion of a single amino acid, 1 nonsense, and 1 frameshift. Among tested variants, 8 showed gain-of-function (GoF), and 6 loss-of-function (LoF) features when expressed heterologously in vitro. Quinidine and fluoxetine blocked all GoF variants, whereas loxapine and riluzole activated some LoF variants while blocking others. INTERPRETATION We expanded the phenotypic and genotypic spectrum of KCNT2-related disorders, highlighting novel genotype-phenotype associations. Pathogenic KCNT2 variants cause GoF or LoF in vitro phenotypes, and each shows a unique pharmacological profile, suggesting the need for in vitro functional and pharmacological investigation to enable targeted therapies based on the molecular phenotype. ANN NEUROL 2023;94:332-349.
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Affiliation(s)
- Maria Cristina Cioclu
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Biomedical, Metabolic, and Neural Science, University of Modena and Reggio Emilia, Modena, Italy
| | - Ilaria Mosca
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Paolo Ambrosino
- Dept. of Science and Technology, University of Sannio, Benevento, Italy
| | - Deborah Puzo
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Allan Bayat
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Saskia B Wortmann
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria
- Amalia Children's Hospital, Nijmegen, The Netherlands
| | - Johannes Koch
- University Children's Hospital, Paracelsus Medical University, Salzburg, Austria
| | - Vincent Strehlow
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Kentaro Shirai
- Department of Pediatrics, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Stephan J Sanders
- Department of Psychiatry and Behavioral Sciences, UCSF Weill Institute for Neurosciences, University of California, San Francisco, CA, USA
- Institute for Human Genetics, University of California, San Francisco, CA, USA
- Bakar Computational Health Sciences Institute, University of California, San Francisco, CA, USA
| | - Vincent Michaud
- Service de Génétique Médicale, Centre de Référence Anomalies du Développement et Syndrome Malformatifs, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Maladies rares: Génétique et Métabolisme (MRGM), INSERM U1211, Université de Bordeaux, Bordeaux, France
| | - Marine Legendre
- Service de Génétique Médicale, Centre de Référence Anomalies du Développement et Syndrome Malformatifs, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
| | - Antonella Riva
- IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Pasquale Striano
- IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Hiltrud Muhle
- Department of Neuropediatrics, University Medical Centre Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - Manuela Pendziwiat
- Department of Neuropediatrics, University Medical Centre Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Gaetan Lesca
- Pathophysiology and Genetics of Neuron and Muscle (PNMG), UCBL, CNRS UMR5261-INSERM U1315, Lyon, France
- Department of Medical Genetics, University Hospital of Lyon and Claude Bernard Lyon I University, Lyon, France
| | - Giuseppe Donato Mangano
- Department of Biomedicine, Neuroscience and Advanced Diagnostics, University of Palermo, Palermo, Italy
| | - Rosaria Nardello
- Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties "G. D'Alessandro", University of Palermo, Palermo, Italy
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Maria Virginia Soldovieri
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
| | - Guido Rubboli
- Department of Epilepsy Genetics and Personalized Medicine (member of ERN EpiCARE), Danish Epilepsy Centre, Dianalund, Denmark
- University of Copenhagen, Copenhagen, Denmark
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Happ HC, Sadleir LG, Zemel M, de Valles-Ibáñez G, Hildebrand MS, McConkie-Rosell A, McDonald M, May H, Sands T, Aggarwal V, Elder C, Feyma T, Bayat A, Møller RS, Fenger CD, Klint Nielsen JE, Datta AN, Gorman KM, King MD, Linhares ND, Burton BK, Paras A, Ellard S, Rankin J, Shukla A, Majethia P, Olson RJ, Muthusamy K, Schimmenti LA, Starnes K, Sedláčková L, Štěrbová K, Vlčková M, Laššuthová P, Jahodová A, Porter BE, Couque N, Colin E, Prouteau C, Collet C, Smol T, Caumes R, Vansenne F, Bisulli F, Licchetta L, Person R, Torti E, McWalter K, Webster R, Gerard EE, Lesca G, Szepetowski P, Scheffer IE, Mefford HC, Carvill GL. Neurodevelopmental and Epilepsy Phenotypes in Individuals With Missense Variants in the Voltage-Sensing and Pore Domains of KCNH5. Neurology 2023; 100:e603-e615. [PMID: 36307226 PMCID: PMC9946193 DOI: 10.1212/wnl.0000000000201492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 09/14/2022] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVES KCNH5 encodes the voltage-gated potassium channel EAG2/Kv10.2. We aimed to delineate the neurodevelopmental and epilepsy phenotypic spectrum associated with de novo KCNH5 variants. METHODS We screened 893 individuals with developmental and epileptic encephalopathies for KCNH5 variants using targeted or exome sequencing. Additional individuals with KCNH5 variants were identified through an international collaboration. Clinical history, EEG, and imaging data were analyzed; seizure types and epilepsy syndromes were classified. We included 3 previously published individuals including additional phenotypic details. RESULTS We report a cohort of 17 patients, including 9 with a recurrent de novo missense variant p.Arg327His, 4 with a recurrent missense variant p.Arg333His, and 4 additional novel missense variants. All variants were located in or near the functionally critical voltage-sensing or pore domains, absent in the general population, and classified as pathogenic or likely pathogenic using the American College of Medical Genetics and Genomics criteria. All individuals presented with epilepsy with a median seizure onset at 6 months. They had a wide range of seizure types, including focal and generalized seizures. Cognitive outcomes ranged from normal intellect to profound impairment. Individuals with the recurrent p.Arg333His variant had a self-limited drug-responsive focal or generalized epilepsy and normal intellect, whereas the recurrent p.Arg327His variant was associated with infantile-onset DEE. Two individuals with variants in the pore domain were more severely affected, with a neonatal-onset movement disorder, early-infantile DEE, profound disability, and childhood death. DISCUSSION We describe a cohort of 17 individuals with pathogenic or likely pathogenic missense variants in the voltage-sensing and pore domains of Kv10.2, including 14 previously unreported individuals. We present evidence for a putative emerging genotype-phenotype correlation with a spectrum of epilepsy and cognitive outcomes. Overall, we expand the role of EAG proteins in human disease and establish KCNH5 as implicated in a spectrum of neurodevelopmental disorders and epilepsy.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Heather C. Mefford
- From the Ken and Ruth Davee Department of Neurology (K.C.H., E.E.G., G.L.C.), Northwestern University Feinberg School of Medicine, Chicago, IL; University of Otago (L.G.S.), Wellington, New Zealand; University of Washington (M.Z.), Seattle; Department of Medicine (G.d.V.-I., R.W., I.E.S.), Epilepsy Research Centre, The University of Melbourne, Austin Health, Heidelberg, Victoria, Australia; Duke University Medical Center (A.M.-R., M.M.), Durham, NC; Institute for Genomic Medicine (H.M., T.S.), Columbia University Irving Medical Center, New York, NY; Departments of Pathology and Cell Biology (V.A.), and Neurology (C.E.), Columbia University Irving Medical Center, New York, NY; Gillette Children's Specialty Healthcare (T.F.), St. Paul, MN; Department of Epilepsy Genetics and Personalized Medicine (A.B., R.S.M., C.D.F.), Danish Epilepsy Center, Dianalund, Denmark; Institute of Regional Health Research (A.B., R.S.M.), University of Southern Denmark; Amplexa Genetics (C.D.F.), Odense, Denmark; Department of Clinical Medicine (J.E.K.N.), Zealand University Hospital, Roskilde, Denmark; University of British Columbia (A.N.D.), Vancouver, Canada; The Department of Neurology and Clinical Neurophysiology (K.M.G., M.D.K.), Children's Health Ireland at Temple St., Dublin 1, Ireland; School of Medicine and Medical Science (K.M.G., M.D.K.), University College Dublin, Ireland; Genuity Science (N.L.), Dublin, Ireland; Ann & Robert H. Lurie Children's Hospital of Chicago (B.K.B., A.P.), Chicago, IL; Department of Pediatrics (B.K.B., A.P., G.L.C.), Northwestern University Feinberg School of Medicine, Chicago, IL; Exeter Genomics Laboratory (S.E.), Royal Devon University Healthcare NHS Foundation Trust, Exeter, United Kingdom; Institute of Clinical and Biomedical Science (S.E.), University of Exeter, United Kingdom; Department Clinical Genetics (J.R.), Royal Devon University Healthcare NHS Foundation Trust, Exeter, United Kingdom; Department of Medical Genetics (A.S., P.M.), Kasturba Medical College, Manipal, Manipal Academy of Higher Education, India; Center for Individualized Medicine (R.J.O., K.M., L.A.S.), Mayo Clinic, Rochester, MN; Departments of Clinical Genomics (K.M., L.A.S.), and Neurology (K.S.), Mayo Clinic, Rochester, MN; Neurogenetic Laboratory (L.S., P.J.), Department of Pediatric Neurology, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Czech Republic; Epilepsy Research Centre Prague—EpiReC Consortium (L.S., K.S., M.V., P.L., A.J.); Motol University Hospital is a full member of the ERN EpiCARE; Department of Pediatric Neurology (K.S., A.J.), Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Czech Republic; Biology and Medical Genetics (M.V.), Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Czech Republic; Stanford University School of Medicine (B.E.P.), Palo Alto, CA; Laboratoire de Biologie médicale multisites Seqoia-FMG2025 (N.C., C.C.), Laboratoire Génétique Moléculaire Robert-Debré, Paris, France; Service de Génétique (E.C., C.P.), CHU d'Angers, Angers, France; University Lille (T.S.), CHU Lille, ULR7364—RADEME, Institut de Genetique Medicale, France; University Lille (R.C.), CHU Lille, ULR7364—RADEME, Clinique de Genetique, France; Univeristy Medical Center Groningen (F.V.), Groningen, the Netherlands; Department of Biomedical and NeuroMotor Sciences (F.B.), University of Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche di Bologna (F.B., L.L.), Full Member of the ERN EpiCARE Bologna, Italy; GeneDx (R.P., E.T., K.M.), Gaithersburg, MD; T.Y. Nelson Department of Neurology and Neurosurgery (R.W.), Children's Hospital at Westmead, Westmead, New South Wales, Australia; Department of Medical Genetics (G.L.), University Hospital of Lyon, Claude Bernard Lyon 1 University, France; INSERM, Aix-Marseille University (P.S.), INMED, France; Department of Neurology (I.E.S.), Royal Children's Hospital, Department of Paediatrics, The University of Melbourne, and Murdoch Children's Research Institute, Parkville, Victoria, Australia; The Florey Institute of Neuroscience and Mental Health (I.E.S.), Victoria, Australia; Center for Pediatric Neurological Disease Research (H.C.M.), St. Jude Children's Research Hospital, Memphis, TN; and Department of Pharmacology (G.L.C.), Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Gemma L. Carvill
- From the Ken and Ruth Davee Department of Neurology (K.C.H., E.E.G., G.L.C.), Northwestern University Feinberg School of Medicine, Chicago, IL; University of Otago (L.G.S.), Wellington, New Zealand; University of Washington (M.Z.), Seattle; Department of Medicine (G.d.V.-I., R.W., I.E.S.), Epilepsy Research Centre, The University of Melbourne, Austin Health, Heidelberg, Victoria, Australia; Duke University Medical Center (A.M.-R., M.M.), Durham, NC; Institute for Genomic Medicine (H.M., T.S.), Columbia University Irving Medical Center, New York, NY; Departments of Pathology and Cell Biology (V.A.), and Neurology (C.E.), Columbia University Irving Medical Center, New York, NY; Gillette Children's Specialty Healthcare (T.F.), St. Paul, MN; Department of Epilepsy Genetics and Personalized Medicine (A.B., R.S.M., C.D.F.), Danish Epilepsy Center, Dianalund, Denmark; Institute of Regional Health Research (A.B., R.S.M.), University of Southern Denmark; Amplexa Genetics (C.D.F.), Odense, Denmark; Department of Clinical Medicine (J.E.K.N.), Zealand University Hospital, Roskilde, Denmark; University of British Columbia (A.N.D.), Vancouver, Canada; The Department of Neurology and Clinical Neurophysiology (K.M.G., M.D.K.), Children's Health Ireland at Temple St., Dublin 1, Ireland; School of Medicine and Medical Science (K.M.G., M.D.K.), University College Dublin, Ireland; Genuity Science (N.L.), Dublin, Ireland; Ann & Robert H. Lurie Children's Hospital of Chicago (B.K.B., A.P.), Chicago, IL; Department of Pediatrics (B.K.B., A.P., G.L.C.), Northwestern University Feinberg School of Medicine, Chicago, IL; Exeter Genomics Laboratory (S.E.), Royal Devon University Healthcare NHS Foundation Trust, Exeter, United Kingdom; Institute of Clinical and Biomedical Science (S.E.), University of Exeter, United Kingdom; Department Clinical Genetics (J.R.), Royal Devon University Healthcare NHS Foundation Trust, Exeter, United Kingdom; Department of Medical Genetics (A.S., P.M.), Kasturba Medical College, Manipal, Manipal Academy of Higher Education, India; Center for Individualized Medicine (R.J.O., K.M., L.A.S.), Mayo Clinic, Rochester, MN; Departments of Clinical Genomics (K.M., L.A.S.), and Neurology (K.S.), Mayo Clinic, Rochester, MN; Neurogenetic Laboratory (L.S., P.J.), Department of Pediatric Neurology, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Czech Republic; Epilepsy Research Centre Prague—EpiReC Consortium (L.S., K.S., M.V., P.L., A.J.); Motol University Hospital is a full member of the ERN EpiCARE; Department of Pediatric Neurology (K.S., A.J.), Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Czech Republic; Biology and Medical Genetics (M.V.), Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Czech Republic; Stanford University School of Medicine (B.E.P.), Palo Alto, CA; Laboratoire de Biologie médicale multisites Seqoia-FMG2025 (N.C., C.C.), Laboratoire Génétique Moléculaire Robert-Debré, Paris, France; Service de Génétique (E.C., C.P.), CHU d'Angers, Angers, France; University Lille (T.S.), CHU Lille, ULR7364—RADEME, Institut de Genetique Medicale, France; University Lille (R.C.), CHU Lille, ULR7364—RADEME, Clinique de Genetique, France; Univeristy Medical Center Groningen (F.V.), Groningen, the Netherlands; Department of Biomedical and NeuroMotor Sciences (F.B.), University of Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche di Bologna (F.B., L.L.), Full Member of the ERN EpiCARE Bologna, Italy; GeneDx (R.P., E.T., K.M.), Gaithersburg, MD; T.Y. Nelson Department of Neurology and Neurosurgery (R.W.), Children's Hospital at Westmead, Westmead, New South Wales, Australia; Department of Medical Genetics (G.L.), University Hospital of Lyon, Claude Bernard Lyon 1 University, France; INSERM, Aix-Marseille University (P.S.), INMED, France; Department of Neurology (I.E.S.), Royal Children's Hospital, Department of Paediatrics, The University of Melbourne, and Murdoch Children's Research Institute, Parkville, Victoria, Australia; The Florey Institute of Neuroscience and Mental Health (I.E.S.), Victoria, Australia; Center for Pediatric Neurological Disease Research (H.C.M.), St. Jude Children's Research Hospital, Memphis, TN; and Department of Pharmacology (G.L.C.), Northwestern University Feinberg School of Medicine, Chicago, IL
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Birk-Barel Intellectual Disability Dimorphism and KCNK9 Imprinting Syndrome: Craniofacial Surgery Considerations for an Exceedingly Rare Syndrome. J Craniofac Surg 2023; 34:e25-e28. [PMID: 35949010 DOI: 10.1097/scs.0000000000008890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 06/06/2022] [Indexed: 01/11/2023] Open
Abstract
Birk-Barel intellectual disability dimorphism syndrome, also referred to as KCNK9 imprinting syndrome, is an exceedingly rare condition described in under 20 cases that presents with intellectual disability, hypotonia, scoliosis, dysphonia, dysphagia, and craniofacial dysmorphic features. The condition follows an autosomal dominant pattern of inheritance in the maternally expressed KCNK9 gene on chromosome 8. Due to the complexity of presentation, patients with Birk-Barel syndrome are optimally managed by a multidisciplinary team including a craniofacial surgeon. Previously described craniofacial dysmorphic features include micrognathia, cleft palate, dolichocephaly, broad nasal tip, and broad philtrum, among others. Here the authors describe a genetically confirmed case that has been managed in our institution's multidisciplinary cleft and craniofacial clinic. The authors aim to discuss Birk-Barel syndrome for a surgical and craniofacial audience with considerations for operative management in the context of a multidisciplinary team.
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Tian M, Li R, Yang F, Shu X, Li J, Chen J, Peng L, Yu X, Yang C. Phenotypic expansion of KCNH1-associated disorders to include isolated epilepsy and its associations with genotypes and molecular sub-regional locations. CNS Neurosci Ther 2022; 29:270-281. [PMID: 36285361 PMCID: PMC9804083 DOI: 10.1111/cns.14001] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/20/2022] [Accepted: 09/29/2022] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Genotype-phenotypic correlation of KCNH1 variant remains elusive. This study aimed to expand the phenotypic spectrum of KCNH1 and explore the correlations between epilepsy and molecular sub-regional locations. METHODS We performed whole-exome sequencing in a cohort of 98 patients with familiar febrile seizure (FS) or epilepsy with unexplained etiologies. The damaging effects of variants were predicted by protein modeling and multiple in silico tools. All reported patients with KCNH1 pathogenic variants with detailed neurological phenotypes were analyzed to evaluate the genotype-phenotype correlation. RESULTS Two novel KCNH1 variants were identified in three cases, including two patients with FS with inherited variant (p.Ile113Thr) and one boy with epilepsy with de novo variant (p.Arg357Trp). Variant Ile113Thr was located within the eag domain, and variant p.Arg357Trp was located in transmembrane domain 4 of KCNH1, respectively. Two patients experienced refractory status epilepticus (SE), of which one patient died of acute encephalopathy induced by SE. Further analysis of 30 variants in 51 patients demonstrated that de novo variants were associated with epileptic encephalopathy, while mosaic/somatic or germline variants cause isolated epilepsy/FS. All hotspot variants associated with epileptic encephalopathy clustered in transmembrane domain (S4 and S6), while those with isolated epilepsy/seizures or TBS/ZLS without epilepsy were scattered in the KCNH1. CONCLUSIONS We found two novel missense variants of KCNH1 in three individuals with isolated FS/epilepsy. Variants in the KCNH1 cause a spectrum of epileptic disorders ranging from a benign form of genetic isolated epilepsy/FS to intractable form of epileptic encephalopathy. The genotypes and variant locations help explaining the phenotypic variation of patients with KCNH1 variant.
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Affiliation(s)
- Mao‐Qiang Tian
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
| | - Ren‐Ke Li
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
| | | | - Xiao‐Mei Shu
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
| | - Juan Li
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
| | - Jing Chen
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
| | - Long‐Ying Peng
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
| | - Xiao‐Hua Yu
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
| | - Chang‐Jian Yang
- Department of PediatricsAffiliated Hospital of Zunyi Medical UniversityZunyiChina,Department of PediatricsGuizhou Children's HospitalZunyiChina
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7
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McClenaghan C, Nichols CG. Kir6.1 and SUR2B in Cantú syndrome. Am J Physiol Cell Physiol 2022; 323:C920-C935. [PMID: 35876283 PMCID: PMC9467476 DOI: 10.1152/ajpcell.00154.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/07/2022] [Accepted: 07/07/2022] [Indexed: 12/25/2022]
Abstract
Kir6.1 and SUR2 are subunits of ATP-sensitive potassium (KATP) channels expressed in a wide range of tissues. Extensive study has implicated roles of these channel subunits in diverse physiological functions. Together they generate the predominant KATP conductance in vascular smooth muscle and are the target of vasodilatory drugs. Roles for Kir6.1/SUR2 dysfunction in disease have been suggested based on studies of animal models and human genetic discoveries. In recent years, it has become clear that gain-of-function (GoF) mutations in both genes result in Cantú syndrome (CS)-a complex, multisystem disorder. There is currently no targeted therapy for CS, but studies of mouse models of the disease reveal that pharmacological reversibility of cardiovascular and gastrointestinal pathologies can be achieved by administration of the KATP channel inhibitor, glibenclamide. Here we review the function, structure, and physiological and pathological roles of Kir6.1/SUR2B channels, with a focus on CS. Recent studies have led to much improved understanding of the underlying pathologies and the potential for treatment, but important questions remain: Can the study of genetically defined CS reveal new insights into Kir6.1/SUR2 function? Do these reveal new pathophysiological mechanisms that may be important in more common diseases? And is our pharmacological armory adequately stocked?
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Affiliation(s)
- Conor McClenaghan
- Department of Cell Biology and Physiology, Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St. Louis, Missouri
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St. Louis, Missouri
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8
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Bauer CK, Holling T, Horn D, Laço MN, Abdalla E, Omar OM, Alawi M, Kutsche K. Clinically Relevant KCNQ1 Variants Causing KCNQ1-KCNE2 Gain-of-Function Affect the Ca2+ Sensitivity of the Channel. Int J Mol Sci 2022; 23:ijms23179690. [PMID: 36077086 PMCID: PMC9456291 DOI: 10.3390/ijms23179690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
Dominant KCNQ1 variants are well-known for underlying cardiac arrhythmia syndromes. The two heterozygous KCNQ1 missense variants, R116L and P369L, cause an allelic disorder characterized by pituitary hormone deficiency and maternally inherited gingival fibromatosis. Increased K+ conductance upon co-expression of KCNQ1 mutant channels with the beta subunit KCNE2 is suggested to underlie the phenotype; however, the reason for KCNQ1-KCNE2 (Q1E2) channel gain-of-function is unknown. We aimed to discover the genetic defect in a single individual and three family members with gingival overgrowth and identified the KCNQ1 variants P369L and V185M, respectively. Patch-clamp experiments demonstrated increased constitutive K+ conductance of V185M-Q1E2 channels, confirming the pathogenicity of the novel variant. To gain insight into the pathomechanism, we examined all three disease-causing KCNQ1 mutants. Manipulation of the intracellular Ca2+ concentration prior to and during whole-cell recordings identified an impaired Ca2+ sensitivity of the mutant KCNQ1 channels. With low Ca2+, wild-type KCNQ1 currents were efficiently reduced and exhibited a pre-pulse-dependent cross-over of current traces and a high-voltage-activated component. These features were absent in mutant KCNQ1 channels and in wild-type channels co-expressed with calmodulin and exposed to high intracellular Ca2+. Moreover, co-expression of calmodulin with wild-type Q1E2 channels and loading the cells with high Ca2+ drastically increased Q1E2 current amplitudes, suggesting that KCNE2 normally limits the resting Q1E2 conductance by an increased demand for calcified calmodulin to achieve effective channel opening. Our data link impaired Ca2+ sensitivity of the KCNQ1 mutants R116L, V185M and P369L to Q1E2 gain-of-function that is associated with a particular KCNQ1 channelopathy.
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Affiliation(s)
- Christiane K. Bauer
- Department of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- Correspondence:
| | - Tess Holling
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Denise Horn
- Department of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin and Berlin Institute of Health, 13353 Berlin, Germany
| | - Mário Nôro Laço
- Medical Genetics Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, 3004-561 Coimbra, Portugal
| | - Ebtesam Abdalla
- Department of Human Genetics, Medical Research Institute, Alexandria University, Alexandria 5422031, Egypt
- Genetics Department, Armed Forces College of Medicine (AFCM), Cairo 4460015, Egypt
| | - Omneya Magdy Omar
- Department of Pediatrics, Faculty of Medicine, Alexandria University, Alexandria 5422031, Egypt
| | - Malik Alawi
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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9
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DeLorenzo L, DeBrock V, Carmona Baez A, Ciccotto PJ, Peterson EN, Stull C, Roberts NB, Roberts RB, Powder KE. Morphometric and Genetic Description of Trophic Adaptations in Cichlid Fishes. BIOLOGY 2022; 11:biology11081165. [PMID: 36009792 PMCID: PMC9405370 DOI: 10.3390/biology11081165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/28/2022] [Accepted: 07/30/2022] [Indexed: 11/16/2022]
Abstract
Since Darwin, biologists have sought to understand the evolution and origins of phenotypic adaptations. The skull is particularly diverse due to intense natural selection on feeding biomechanics. We investigated the genetic and molecular origins of trophic adaptation using Lake Malawi cichlids, which have undergone an exemplary evolutionary radiation. We analyzed morphological differences in the lateral and ventral head shape among an insectivore that eats by suction feeding, an obligate biting herbivore, and their F2 hybrids. We identified variation in a series of morphological traits—including mandible width, mandible length, and buccal length—that directly affect feeding kinematics and function. Using quantitative trait loci (QTL) mapping, we found that many genes of small effects influence these craniofacial adaptations. Intervals for some traits were enriched in genes related to potassium transport and sensory systems, the latter suggesting co-evolution of feeding structures and sensory adaptations for foraging. Despite these indications of co-evolution of structures, morphological traits did not show covariation. Furthermore, phenotypes largely mapped to distinct genetic intervals, suggesting that a common genetic basis does not generate coordinated changes in shape. Together, these suggest that craniofacial traits are mostly inherited as separate modules, which confers a high potential for the evolution of morphological diversity. Though these traits are not restricted by genetic pleiotropy, functional demands of feeding and sensory structures likely introduce constraints on variation. In all, we provide insights into the quantitative genetic basis of trophic adaptation, identify mechanisms that influence the direction of morphological evolution, and provide molecular inroads to craniofacial variation.
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Affiliation(s)
- Leah DeLorenzo
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Victoria DeBrock
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Aldo Carmona Baez
- Department of Biological Sciences and Genetics and Genomics Academy, North Carolina State University, Raleigh, NC 27695, USA
| | - Patrick J Ciccotto
- Department of Biological Sciences and Genetics and Genomics Academy, North Carolina State University, Raleigh, NC 27695, USA
- Department of Biology, Warren Wilson College, Swannanoa, NC 28778, USA
| | - Erin N Peterson
- Department of Biological Sciences and Genetics and Genomics Academy, North Carolina State University, Raleigh, NC 27695, USA
| | - Clare Stull
- Department of Biological Sciences and Genetics and Genomics Academy, North Carolina State University, Raleigh, NC 27695, USA
| | - Natalie B Roberts
- Department of Biological Sciences and Genetics and Genomics Academy, North Carolina State University, Raleigh, NC 27695, USA
| | - Reade B Roberts
- Department of Biological Sciences and Genetics and Genomics Academy, North Carolina State University, Raleigh, NC 27695, USA
| | - Kara E Powder
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
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10
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Nichols CG, McClenaghan C. Bridging Personal and Population in Excitability Diseases: Will Studies of Rare Diseases Bring Generalizable Mechanisms From Monogenic Channelopathies? FUNCTION (OXFORD, ENGLAND) 2022; 3:zqab072. [PMID: 35402918 PMCID: PMC8991026 DOI: 10.1093/function/zqab072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 12/29/2021] [Accepted: 12/21/2021] [Indexed: 01/07/2023]
Affiliation(s)
| | - Conor McClenaghan
- Center for the Investigation of Membrane Excitability Diseases, and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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11
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Schwarz M, Ryba L, Křepelová A, Moslerová V, Zelinová M, Turnovec M, Martinková J, Kratochvílová L, Drahanský M, Macek M, Havlovicová M. Zimmermann-Laband syndrome in monozygotic twins with a mild neurobehavioral phenotype lacking gingival overgrowth-A case report of a novel KCNN3 gene variant. Am J Med Genet A 2021; 188:1083-1087. [PMID: 34907639 DOI: 10.1002/ajmg.a.62616] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 11/08/2022]
Abstract
Zimmermann-Laband syndrome is a rare, heterogeneous disorder characterized by gingival hypertrophy or fibromatosis, aplastic/hypoplastic nails, hypoplasia of the distal phalanges, hypertrichosis, various degrees of intellectual disability, and distinctive facial features. Three genes are considered causative for ZLS: KCNH1, KCNN3, and ATP6V1B2. We report on a pair of female concordant monozygotic twins, both carrying a novel pathogenic variant in the KCNN3 gene, identified using exome sequencing. Only six ZLS patients with the KCNN3 pathogenic variant have been reported so far. The twins show facial dysmorphism, hypoplastic distal phalanges, aplasia or hypoplasia of nails, and hypertrichosis. During infancy, they showed mild developmental delays, mainly speech. They successfully completed secondary school education and are socio-economically independent. Gingival overgrowth is absent in both individuals. Our patients exhibited an unusually mild phenotype compared to published cases, which is an important diagnostic finding for proper genetic counseling for Zimmermann-Laband syndrome patients and their families.
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Affiliation(s)
- Martin Schwarz
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Lukáš Ryba
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Anna Křepelová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Veronika Moslerová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Michaela Zelinová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Marek Turnovec
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Júlia Martinková
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Lenka Kratochvílová
- Department of Stomatology, Motol University Hospital, Prague, Czech Republic
| | - Martin Drahanský
- Department of Intelligent Systems, Faculty of Information Technology, Brno University of Technology, Brno, Czech Republic
| | - Milan Macek
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Markéta Havlovicová
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
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12
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KCNG1-Related Syndromic Form of Congenital Neuromuscular Channelopathy in a Crossbred Calf. Genes (Basel) 2021; 12:genes12111792. [PMID: 34828398 PMCID: PMC8618021 DOI: 10.3390/genes12111792] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 10/29/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Inherited channelopathies are a clinically and heritably heterogeneous group of disorders that result from ion channel dysfunction. The aim of this study was to characterize the clinicopathologic features of a Belgian Blue x Holstein crossbred calf with paradoxical myotonia congenita, craniofacial dysmorphism, and myelodysplasia, and to identify the most likely genetic etiology. The calf displayed episodes of exercise-induced generalized myotonic muscle stiffness accompanied by increase in serum potassium. It also showed slight flattening of the splanchnocranium with deviation to the right side. On gross pathology, myelodysplasia (hydrosyringomielia and segmental hypoplasia) in the lumbosacral intumescence region was noticed. Histopathology of the muscle profile revealed loss of the main shape in 5.3% of muscle fibers. Whole-genome sequencing revealed a heterozygous missense variant in KCNG1 affecting an evolutionary conserved residue (p.Trp416Cys). The mutation was predicted to be deleterious and to alter the pore helix of the ion transport domain of the transmembrane protein. The identified variant was present only in the affected calf and not seen in more than 5200 other sequenced bovine genomes. We speculate that the mutation occurred either as a parental germline mutation or post-zygotically in the developing embryo. This study implicates an important role for KCNG1 as a member of the potassium voltage-gated channel group in neurodegeneration. Providing the first possible KCNG1-related disease model, we have, therefore, identified a new potential candidate for related conditions both in animals and in humans. This study illustrates the enormous potential of phenotypically well-studied spontaneous mutants in domestic animals to provide new insights into the function of individual genes.
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13
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Monitoring of compound resting membrane potentials of cell cultures with ratiometric genetically encoded voltage indicators. Commun Biol 2021; 4:1164. [PMID: 34620975 PMCID: PMC8497494 DOI: 10.1038/s42003-021-02675-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 09/13/2021] [Indexed: 11/29/2022] Open
Abstract
The cellular resting membrane potential (Vm) not only determines electrical responsiveness of excitable cells but also plays pivotal roles in non-excitable cells, mediating membrane transport, cell-cycle progression, and tumorigenesis. Studying these processes requires estimation of Vm, ideally over long periods of time. Here, we introduce two ratiometric genetically encoded Vm indicators, rArc and rASAP, and imaging and analysis procedures for measuring differences in average resting Vm between cell groups. We investigated the influence of ectopic expression of K+ channels and their disease-causing mutations involved in Andersen-Tawil (Kir2.1) and Temple-Baraitser (KV10.1) syndrome on median resting Vm of HEK293T cells. Real-time long-term monitoring of Vm changes allowed to estimate a 40–50 min latency from induction of transcription to functional Kir2.1 channels in HEK293T cells. The presented methodology is readily implemented with standard fluorescence microscopes and offers deeper insights into the role of the resting Vm in health and disease. Rühl et al. report the generation of ratiometric genetically encoded voltage indicators (GEVIs) and establish that they can be used in high-throughput automated imaging to measure compound membrane potential (Vm) in mammalian cells. This method is implementable with standard fluorescence microscopes and has the potential to offer insights into the role of the resting Vm in health and disease.
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14
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Zhang Y, Tachtsidis G, Schob C, Koko M, Hedrich UBS, Lerche H, Lemke JR, Haeringen A, Ruivenkamp C, Prescott T, Tveten K, Gerstner T, Pruniski B, DiTroia S, VanNoy GE, Rehm HL, McLaughlin H, Bolz HJ, Zechner U, Bryant E, McDonough T, Kindler S, Bähring R. KCND2 variants associated with global developmental delay differentially impair Kv4.2 channel gating. Hum Mol Genet 2021; 30:2300-2314. [PMID: 34245260 DOI: 10.1093/hmg/ddab192] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 11/13/2022] Open
Abstract
Here, we report on six unrelated individuals, all presenting with early-onset global developmental delay, associated with impaired motor, speech and cognitive development, partly with developmental epileptic encephalopathy and physical dysmorphisms. All individuals carry heterozygous missense variants of KCND2, which encodes the voltage-gated potassium (Kv) channel α-subunit Kv4.2. The amino acid substitutions associated with the variants, p.(Glu323Lys) (E323K), p.(Pro403Ala) (P403A), p.(Val404Leu) (V404L) and p.(Val404Met) (V404M), affect sites known to be critical for channel gating. To unravel their likely pathogenicity, recombinant mutant channels were studied in the absence and presence of auxiliary β-subunits under two-electrode voltage-clamp in Xenopus oocytes. All channel mutants exhibited slowed and incomplete macroscopic inactivation, and the P403A variant in addition slowed activation. Co-expression of KChIP2 or DPP6 augmented the functional expression of both wild-type and mutant channels, however, the auxiliary β-subunit-mediated gating modifications differed from wild-type and among mutants. To simulate the putative setting in the affected individuals, heteromeric Kv4.2 channels (wild-type + mutant) were studied as ternary complexes (containing both KChIP2 and DPP6). In the heteromeric ternary configuration, the E323K variant exhibited only marginal functional alterations compared to homomeric wild-type ternary, compatible with mild loss-of-function. By contrast, the P403A, V404L and V404M variants displayed strong gating impairment in the heteromeric ternary configuration, compatible with loss or gain-of-function. Our results support the etiological involvement of Kv4.2 channel gating impairment in early-onset monogenic global developmental delay. In addition, they suggest that gain-of-function mechanisms associated with a substitution of V404 increase epileptic seizure susceptibility.
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Affiliation(s)
- Yongqiang Zhang
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,Southeast University, Nanjing, China
| | - Georgios Tachtsidis
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Claudia Schob
- Institute for Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Mahmoud Koko
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Ulrike B S Hedrich
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Johannes R Lemke
- University Center for Rare Diseases, Institute for Human Genetics, University Hospital, Leipzig, Germany
| | - Arie Haeringen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Claudia Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Trine Prescott
- Department of Medical Genetics, Telemark Hospital Trust, Skien, Norway
| | - Kristian Tveten
- Department of Medical Genetics, Telemark Hospital Trust, Skien, Norway
| | - Thorsten Gerstner
- Department of Child Neurology and Rehabilitation and Department of Pediatrics, Hospital of Southern Norway, Arendal, Norway
| | - Brianna Pruniski
- Division of Genetics & Metabolism, Phoenix Children's Medical Group, Phoenix, AZ, USA
| | - Stephanie DiTroia
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Grace E VanNoy
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Heidi L Rehm
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | | | - Hanno J Bolz
- Senckenberg Centre for Human Genetics, Frankfurt/Main, Germany.,Institute of Human Genetics, University Hospital of Cologne, Cologne, Germany
| | - Ulrich Zechner
- Senckenberg Centre for Human Genetics, Frankfurt/Main, Germany.,Institute of Human Genetics, University Medical Center Mainz, Mainz, Germany
| | - Emily Bryant
- Ann & Robert H Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg Scool of Medicine, Chicago, IL, USA
| | - Tiffani McDonough
- Ann & Robert H Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg Scool of Medicine, Chicago, IL, USA
| | - Stefan Kindler
- Institute for Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Robert Bähring
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany
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15
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Gripp KW, Smithson SF, Scurr IJ, Baptista J, Majumdar A, Pierre G, Williams M, Henderson LB, Wentzensen IM, McLaughlin H, Leeuwen L, Simon MEH, van Binsbergen E, Dinulos MBP, Kaplan JD, McRae A, Superti-Furga A, Good JM, Kutsche K. Syndromic disorders caused by gain-of-function variants in KCNH1, KCNK4, and KCNN3-a subgroup of K + channelopathies. Eur J Hum Genet 2021; 29:1384-1395. [PMID: 33594261 PMCID: PMC8440610 DOI: 10.1038/s41431-021-00818-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/18/2021] [Accepted: 01/22/2021] [Indexed: 12/13/2022] Open
Abstract
Decreased or increased activity of potassium channels caused by loss-of-function and gain-of-function (GOF) variants in the corresponding genes, respectively, underlies a broad spectrum of human disorders affecting the central nervous system, heart, kidney, and other organs. While the association of epilepsy and intellectual disability (ID) with variants affecting function in genes encoding potassium channels is well known, GOF missense variants in K+ channel encoding genes in individuals with syndromic developmental disorders have only recently been recognized. These syndromic phenotypes include Zimmermann–Laband and Temple–Baraitser syndromes, caused by dominant variants in KCNH1, FHEIG syndrome due to dominant variants in KCNK4, and the clinical picture associated with dominant variants in KCNN3. Here we review the presentation of these individuals, including five newly reported with variants in KCNH1 and three additional individuals with KCNN3 variants, all variants likely affecting function. There is notable overlap in the phenotypic findings of these syndromes associated with dominant KCNN3, KCNH1, and KCNK4 variants, sharing developmental delay and/or ID, coarse facial features, gingival enlargement, distal digital hypoplasia, and hypertrichosis. We suggest to combine the phenotypes and define a new subgroup of potassium channelopathies caused by increased K+ conductance, referred to as syndromic neurodevelopmental K+ channelopathies due to dominant variants in KCNH1, KCNK4, or KCNN3.
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Affiliation(s)
- Karen W Gripp
- Division of Medical Genetics, Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Sarah F Smithson
- Department of Clinical Genetics, University Hospitals Bristol and Weston, Bristol, UK
| | - Ingrid J Scurr
- Department of Clinical Genetics, University Hospitals Bristol and Weston, Bristol, UK
| | - Julia Baptista
- Exeter Genomics Laboratory, Royal Devon & Exeter NHS Foundation Trust, Exeter, UK.,College of Medicine and Health, University of Exeter, Exeter, UK
| | - Anirban Majumdar
- Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK
| | - Germaine Pierre
- Department of Paediatric Metabolic Medicine, Bristol Royal Hospital for Children, Bristol, UK
| | - Maggie Williams
- Bristol Genetics Laboratory, North Bristol NHS Trust, Bristol, UK
| | | | | | | | - Lisette Leeuwen
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marleen E H Simon
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ellen van Binsbergen
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mary Beth P Dinulos
- Section of Genetics and Child Development, Children's Hospital at Dartmouth, Lebanon, NH, USA
| | - Julie D Kaplan
- Division of Medical Genetics, Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Anne McRae
- Division of Genetics, Birth Defects and Metabolism, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Andrea Superti-Furga
- Division of Genetic Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Jean-Marc Good
- Division of Genetic Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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