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Marini C, Romoli M, Parrini E, Costa C, Mei D, Mari F, Parmeggiani L, Procopio E, Metitieri T, Cellini E, Virdò S, De Vita D, Gentile M, Prontera P, Calabresi P, Guerrini R. Clinical features and outcome of 6 new patients carrying de novo KCNB1 gene mutations. NEUROLOGY-GENETICS 2017; 3:e206. [PMID: 29264397 PMCID: PMC5733250 DOI: 10.1212/nxg.0000000000000206] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 09/07/2017] [Indexed: 01/01/2023]
Abstract
Objective To describe electroclinical features and outcome of 6 patients harboring KCNB1 mutations. Methods Clinical, EEG, neuropsychological, and brain MRI data analysis. Targeted next-generation sequencing of a 95 epilepsy gene panel. Results The mean age at seizure onset was 11 months. The mean follow-up of 11.3 years documented that 4 patients following an infantile phase of frequent seizures became seizure free; the mean age at seizure offset was 4.25 years. Epilepsy phenotypes comprised West syndrome in 2 patients, infantile-onset unspecified generalized epilepsy, myoclonic and photosensitive eyelid myoclonia epilepsy resembling Jeavons syndrome, Lennox-Gastaut syndrome, and focal epilepsy with prolonged occipital or clonic seizures in each and every one. Five patients had developmental delay prior to seizure onset evolving into severe intellectual disability with absent speech and autistic traits in one and stereotypic hand movements with impulse control disorder in another. The patient with Jeavons syndrome evolved into moderate intellectual disability. Mutations were de novo, 4 missense and 2 nonsense, 5 were novel, and 1 resulted from somatic mosaicism. Conclusions KCNB1-related manifestations include a spectrum of infantile-onset generalized or focal seizures whose combination leads to early infantile epileptic encephalopathy including West, Lennox-Gastaut, and Jeavons syndromes. Long-term follow-up highlights that following a stormy phase, seizures subside or cease and treatment may be eased or withdrawn. Cognitive and motor functions are almost always delayed prior to seizure onset and evolve into severe, persistent impairment. Thus, KCNB1 mutations are associated with diffuse brain dysfunction combining seizures, motor, and cognitive impairment.
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Affiliation(s)
- Carla Marini
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Michele Romoli
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Elena Parrini
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Cinzia Costa
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Davide Mei
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Francesco Mari
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Lucio Parmeggiani
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Elena Procopio
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Tiziana Metitieri
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Elena Cellini
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Simona Virdò
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Dalila De Vita
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Mattia Gentile
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Paolo Prontera
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Paolo Calabresi
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
| | - Renzo Guerrini
- Pediatric Neurology Unit (C.M., E.P., D.M., F.M., T.M., E.C., S.V., D.D.V., R.G.), Neurogenetics and Neurobiology Laboratories, Neuroscience Department, A. Meyer Pediatric Hospital, University of Florence; Neurology Unit (M.R., C.C., P.C.), Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia; Child Neurology Service (L.P.), Hospital of Bolzano; Metabolic Unit (E.P.), A. Meyer Pediatric Hospital, Florence; Medical Genetics Unit (M.G.), Azienda Sanitaria Locale Bari; Neonatology Unit and Prenatal Diagnosis (P.P.), Medical Genetic Unit, Ospedale S. Maria della Misericordia, Perugia; Department of Experimental Neurosciences (P.C.), "Istituto di Ricovero e Cura a Carattere Scientifico," IRCCS Santa Lucia Foundation, Rome; and IRCCS Stella Maris Foundation (R.G.), Calambrone, Pisa, Italy
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Calhoun JD, Vanoye CG, Kok F, George AL, Kearney JA. Characterization of a KCNB1 variant associated with autism, intellectual disability, and epilepsy. NEUROLOGY-GENETICS 2017; 3:e198. [PMID: 29264390 PMCID: PMC5733249 DOI: 10.1212/nxg.0000000000000198] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 10/15/2017] [Indexed: 11/26/2022]
Abstract
Objective: To perform functional characterization of a potentially pathogenic KCNB1 variant identified by clinical exome sequencing of a proband with a neurodevelopmental disorder that included epilepsy and centrotemporal spikes on EEG. Methods: Whole-exome sequencing identified the KCNB1 variant c.595A>T (p.Ile199Phe). Biochemical and electrophysiologic experiments were performed to determine whether this variant affected protein expression, trafficking, and channel functional properties. Results: Biochemical characterization of the variant suggested normal protein expression and trafficking. Functional characterization revealed biophysical channel defects in assembled homotetrameric and heterotetrameric channels. Conclusions: The identification of the KCNB1 variant c.595A>T (p.Ile199Phe) in a neurodevelopmental disorder that included epilepsy with centrotemporal spikes expands the phenotypic spectrum of epilepsies associated with KCNB1 variants. The KCNB1-I199F variant exhibited partial loss of function relative to the wild-type channel. This defect is arguably less severe than previously reported KCNB1 variants, suggesting the possibility that the degree of KCNB1 protein dysfunction may influence disease severity.
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Affiliation(s)
- Jeffrey D Calhoun
- Department of Pharmacology (J.D.C., C.G.V., A.L.G., J.A.K.), Northwestern University Feinberg School of Medicine, Chicago, IL; Human Genome and Stem Cell Research Center (F.K.), Biosciences Institute, University of Sao Paulo, Brazil; and Mendelics Análise Genomica (F.K.), Sao Paulo, Brazil
| | - Carlos G Vanoye
- Department of Pharmacology (J.D.C., C.G.V., A.L.G., J.A.K.), Northwestern University Feinberg School of Medicine, Chicago, IL; Human Genome and Stem Cell Research Center (F.K.), Biosciences Institute, University of Sao Paulo, Brazil; and Mendelics Análise Genomica (F.K.), Sao Paulo, Brazil
| | - Fernando Kok
- Department of Pharmacology (J.D.C., C.G.V., A.L.G., J.A.K.), Northwestern University Feinberg School of Medicine, Chicago, IL; Human Genome and Stem Cell Research Center (F.K.), Biosciences Institute, University of Sao Paulo, Brazil; and Mendelics Análise Genomica (F.K.), Sao Paulo, Brazil
| | - Alfred L George
- Department of Pharmacology (J.D.C., C.G.V., A.L.G., J.A.K.), Northwestern University Feinberg School of Medicine, Chicago, IL; Human Genome and Stem Cell Research Center (F.K.), Biosciences Institute, University of Sao Paulo, Brazil; and Mendelics Análise Genomica (F.K.), Sao Paulo, Brazil
| | - Jennifer A Kearney
- Department of Pharmacology (J.D.C., C.G.V., A.L.G., J.A.K.), Northwestern University Feinberg School of Medicine, Chicago, IL; Human Genome and Stem Cell Research Center (F.K.), Biosciences Institute, University of Sao Paulo, Brazil; and Mendelics Análise Genomica (F.K.), Sao Paulo, Brazil
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de Kovel CGF, Syrbe S, Brilstra EH, Verbeek N, Kerr B, Dubbs H, Bayat A, Desai S, Naidu S, Srivastava S, Cagaylan H, Yis U, Saunders C, Rook M, Plugge S, Muhle H, Afawi Z, Klein KM, Jayaraman V, Rajagopalan R, Goldberg E, Marsh E, Kessler S, Bergqvist C, Conlin LK, Krok BL, Thiffault I, Pendziwiat M, Helbig I, Polster T, Borggraefe I, Lemke JR, van den Boogaardt MJ, Møller RS, Koeleman BPC. Neurodevelopmental Disorders Caused by De Novo Variants in KCNB1 Genotypes and Phenotypes. JAMA Neurol 2017; 74:1228-1236. [PMID: 28806457 DOI: 10.1001/jamaneurol.2017.1714] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Importance Knowing the range of symptoms seen in patients with a missense or loss-of-function variant in KCNB1 and how these symptoms correlate with the type of variant will help clinicians with diagnosis and prognosis when treating new patients. Objectives To investigate the clinical spectrum associated with KCNB1 variants and the genotype-phenotype correlations. Design, Setting, and Participants This study summarized the clinical and genetic information of patients with a presumed pathogenic variant in KCNB1. Patients were identified in research projects or during clinical testing. Information on patients from previously published articles was collected and authors contacted if feasible. All patients were seen at a clinic at one of the participating institutes because of presumed genetic disorder. They were tested in a clinical setting or included in a research project. Main Outcomes and Measures The genetic variant and its inheritance and information on the patient's symptoms and characteristics in a predefined format. All variants were identified with massive parallel sequencing and confirmed with Sanger sequencing in the patient. Absence of the variant in the parents could be confirmed with Sanger sequencing in all families except one. Results Of 26 patients (10 female, 15 male, 1 unknown; mean age at inclusion, 9.8 years; age range, 2-32 years) with developmental delay, 20 (77%) carried a missense variant in the ion channel domain of KCNB1, with a concentration of variants in region S5 to S6. Three variants that led to premature stops were located in the C-terminal and 3 in the ion channel domain. Twenty-one of 25 patients (84%) had seizures, with 9 patients (36%) starting with epileptic spasms between 3 and 18 months of age. All patients had developmental delay, with 17 (65%) experiencing severe developmental delay; 14 (82%) with severe delay had behavioral problems. The developmental delay was milder in 4 of 6 patients with stop variants and in a patient with a variant in the S2 transmembrane element rather than the S4 to S6 region. Conclusions and Relevance De novo KCNB1 missense variants in the ion channel domain and loss-of-function variants in this domain and the C-terminal likely cause neurodevelopmental disorders with or without seizures. Patients with presumed pathogenic variants in KCNB1 have a variable phenotype. However, the type and position of the variants in the protein are (imperfectly) correlated with the severity of the disorder.
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Affiliation(s)
- Carolien G F de Kovel
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands.,Department of Language and Genetics, Max Planck Institute for Psycholinguistics, Nijmegen, the Netherlands
| | - Steffen Syrbe
- Division of Child Neurology and Inherited Metabolic Diseases, Department of General Pediatrics, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Eva H Brilstra
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Nienke Verbeek
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Bronwyn Kerr
- Institute of Evolution, Systems and Genomics, Faculty of Medical and Human Sciences, University of Manchester, Manchester, England.,Manchester Centre For Genomic Medicine, Central Manchester University Hospitals National Health Service Foundation Trust, Manchester, England.,Manchester Academic Health Science Centre, Manchester, England
| | - Holly Dubbs
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Allan Bayat
- Department of Pediatrics, University Hospital of Hvidovre, Copenhagen, Denmark
| | - Sonal Desai
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland
| | - Sakkubai Naidu
- Department of Neurology and Pediatrics, Johns Hopkins School of Medicine, Baltimore, Maryland.,Hugo Moser Research Institute, Kennedy Krieger Institute, Baltimore, Maryland
| | | | - Hande Cagaylan
- Department of Molecular Biology and Genetics, Bogaziçi University, Istanbul, Turkey
| | - Uluc Yis
- Division of Child Neurology, Department of Pediatrics, School of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Carol Saunders
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, Missouri.,Department of Pediatrics, Children's Mercy Hospital, Kansas City, Missouri.,Pediatric Pathology and Laboratory Medicine, University of Missouri-Kansas City School of Medicine, Kansas City
| | - Martin Rook
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Susanna Plugge
- Department of Biomedical Sciences, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Hiltrud Muhle
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian Albrechts University, Kiel, Germany
| | - Zaid Afawi
- Department of Physiology and Pharmacology, Tel Aviv University Medical School, Ramat Aviv, Israel
| | - Karl-Martin Klein
- Department of Neurology, Epilepsy Center Frankfurt Rhine-Main, Center of Neurology and Neurosurgery, University Hospital, Goethe-University Frankfurt, Frankfurt, Germany
| | - Vijayakumar Jayaraman
- Division of Genomic Diagnostics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Ramakrishnan Rajagopalan
- Division of Genomic Diagnostics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Ethan Goldberg
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Eric Marsh
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Sudha Kessler
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Christina Bergqvist
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Laura K Conlin
- Division of Genomic Diagnostics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Bryan L Krok
- Division of Genomic Diagnostics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Isabelle Thiffault
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, Missouri.,Department of Pediatrics, Children's Mercy Hospital, Kansas City, Missouri
| | - Manuela Pendziwiat
- Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian Albrechts University, Kiel, Germany
| | - Ingo Helbig
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,University Medical Center Schleswig-Holstein, Christian Albrechts University, Kiel, Germany
| | - Tilman Polster
- Epilepsiezentrum Bethel, Krankenhaus Mara, Kinderepileptologie, Bielefeld, Germany
| | - Ingo Borggraefe
- Department of Pediatric Neurology, Developmental Medicine and Social Pediatrics Dr. von Hauner's Children's Hospital, University of Munich, Munich, Germany
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany
| | | | - Rikke S Møller
- Danish Epilepsy Centre, Dianalund, Denmark.,Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Bobby P C Koeleman
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
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Trafficking of Kv2.1 Channels to the Axon Initial Segment by a Novel Nonconventional Secretory Pathway. J Neurosci 2017; 37:11523-11536. [PMID: 29042434 DOI: 10.1523/jneurosci.3510-16.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 09/09/2017] [Indexed: 02/07/2023] Open
Abstract
Kv2.1 is a major delayed-rectifier voltage-gated potassium channel widely expressed in neurons of the CNS. Kv2.1 localizes in high-density cell-surface clusters in the soma and proximal dendrites as well as in the axon initial segment (AIS). Given the crucial roles of both of these compartments in integrating signal input and then generating output, this localization of Kv2.1 is ideal for regulating the overall excitability of neurons. Here we used fluorescence recovery after photobleaching imaging, mutagenesis, and pharmacological interventions to investigate the molecular mechanisms that control the localization of Kv2.1 in these two different membrane compartments in cultured rat hippocampal neurons of mixed sex. Our data uncover a unique ability of Kv2.1 channels to use two molecularly distinct trafficking pathways to accomplish this. Somatodendritic Kv2.1 channels are targeted by the conventional secretory pathway, whereas axonal Kv2.1 channels are targeted by a nonconventional trafficking pathway independent of the Golgi apparatus. We further identified a new AIS trafficking motif in the C-terminus of Kv2.1, and show that putative phosphorylation sites in this region are critical for the restricted and clustered localization in the AIS. These results indicate that neurons can regulate the expression and clustering of Kv2.1 in different membrane domains independently by using two distinct localization mechanisms, which would allow neurons to precisely control local membrane excitability.SIGNIFICANCE STATEMENT Our study uncovered a novel mechanism that targets the Kv2.1 voltage-gated potassium channel to two distinct trafficking pathways and two distinct subcellular destinations: the somatodendritic plasma membrane and that of the axon initial segment. We also identified a distinct motif, including putative phosphorylation sites, that is important for the AIS localization. This raises the possibility that the destination of a channel protein can be dynamically regulated via changes in post-translational modification, which would impact the excitability of specific membrane compartments.
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55
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Maljevic S, Reid CA, Petrou S. Models for discovery of targeted therapy in genetic epileptic encephalopathies. J Neurochem 2017; 143:30-48. [PMID: 28742937 DOI: 10.1111/jnc.14134] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/14/2017] [Accepted: 07/19/2017] [Indexed: 12/20/2022]
Abstract
Epileptic encephalopathies are severe disorders emerging in the first days to years of life that commonly include refractory seizures, various types of movement disorders, and different levels of developmental delay. In recent years, many de novo occurring variants have been identified in individuals with these devastating disorders. To unravel disease mechanisms, the functional impact of detected variants associated with epileptic encephalopathies is investigated in a range of cellular and animal models. This review addresses efforts to advance and use such models to identify specific molecular and cellular targets for the development of novel therapies. We focus on ion channels as the best-studied group of epilepsy genes. Given the clinical and genetic heterogeneity of epileptic encephalopathy disorders, experimental models that can reflect this complexity are critical for the development of disease mechanisms-based targeted therapy. The convergence of technological advances in gene sequencing, stem cell biology, genome editing, and high throughput functional screening together with massive unmet clinical needs provides unprecedented opportunities and imperatives for precision medicine in epileptic encephalopathies.
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Affiliation(s)
- Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia.,University of Melbourne, Melbourne, Australia
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56
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Pal LR, Kundu K, Yin Y, Moult J. CAGI4 SickKids clinical genomes challenge: A pipeline for identifying pathogenic variants. Hum Mutat 2017; 38:1169-1181. [PMID: 28512736 PMCID: PMC5577808 DOI: 10.1002/humu.23257] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 12/21/2022]
Abstract
Compared with earlier more restricted sequencing technologies, identification of rare disease variants using whole-genome sequence has the possibility of finding all causative variants, but issues of data quality and an overwhelming level of background variants complicate the analysis. The CAGI4 SickKids clinical genome challenge provided an opportunity to assess the landscape of variants found in a difficult set of 25 unsolved rare disease cases. To address the challenge, we developed a three-stage pipeline, first carefully analyzing data quality, then classifying high-quality gene-specific variants into seven categories, and finally examining each candidate variant for compatibility with the often complex phenotypes of these patients for final prioritization. Variants consistent with the phenotypes were found in 24 out of the 25 cases, and in a number of these, there are prioritized variants in multiple genes. Data quality analysis suggests that some of the selected variants are likely incorrect calls, complicating interpretation. The data providers followed up on three suggested variants with Sanger sequencing, and in one case, a prioritized variant was confirmed as likely causative by the referring physician, providing a diagnosis in a previously intractable case.
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Affiliation(s)
- Lipika R. Pal
- Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD 20850
| | - Kunal Kundu
- Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD 20850
- Computational Biology, Bioinformatics and Genomics, Biological Sciences Graduate Program, University of Maryland, College Park, MD 20742, USA
| | - Yizhou Yin
- Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD 20850
- Computational Biology, Bioinformatics and Genomics, Biological Sciences Graduate Program, University of Maryland, College Park, MD 20742, USA
| | - John Moult
- Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD 20850
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742
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57
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Prenatal diagnosis of complex phenotype in a 13-week-old fetus with an interstitial multigene deletion 20q13.13.-q13.2 by chromosomal microarray. Eur J Med Genet 2017; 60:589-594. [PMID: 28807863 DOI: 10.1016/j.ejmg.2017.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 05/29/2017] [Accepted: 08/10/2017] [Indexed: 11/21/2022]
Abstract
We report the first trimester three-dimensional ultrasonographic findings in a 13-week-old fetus with complex phenotype and a de novo 4.7 Mb multigene deletion encompassing chromosome region 20q13.13-q13.2 detected by chromosomal microarray. Fetal sonography detected radial-ray anomalies in the form of bilateral absence of thumbs and the left club hand deformity. The presence of single atrioventricular canal instead of the atrial septal defect typical for Holt-Oram syndrome pointed us to rather suspect the SALL4 related diseases. Central nervous system anomaly in the form of enlarged lateral brain ventricles with choroid plexus shifted backwards was not previously reported as a part of SALL4 related disorders. The pregnancy was terminated at 14 + 3 weeks of pregnancy and the autopsy confirmed ultrasonographic findings. Deleted region included 38 genes, where only SALL4, ADNP and KCNB1 heterozygote pathogenic variants were described to be cause of syndromic forms. Radial ray anomalies are common part of clinical picture of SALL4 related disorders. Despite the lack of prenatally described cases, we hypothesized that maldevelopment of lateral brain ventriculomegaly could be very early sonographic sign of disturbed ADNP expression causing Helsmoortel-Van der Aa syndrome, but in some extent also of KCNB1 related early-onset epileptic encephalopathy. Furthermore, the possible dosage-dependent influence of recessive genes located in this region cannot be also excluded. The use of genome-wide technologies enables the detection of subtle chromosomal imbalances and more precise familial genetic counseling regarding actual and future pregnancies.
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58
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Venom-derived peptide inhibitors of voltage-gated potassium channels. Neuropharmacology 2017; 127:124-138. [PMID: 28689025 DOI: 10.1016/j.neuropharm.2017.07.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/02/2017] [Accepted: 07/04/2017] [Indexed: 12/11/2022]
Abstract
Voltage-gated potassium channels play a key role in human physiology and pathology. Reflecting their importance, numerous channelopathies have been characterised that arise from mutations in these channels or from autoimmune attack on the channels. Voltage-gated potassium channels are also the target of a broad range of peptide toxins from venomous organisms, including sea anemones, scorpions, spiders, snakes and cone snails; many of these peptides bind to the channels with high potency and selectivity. In this review we describe the various classes of peptide toxins that block these channels and illustrate the broad range of three-dimensional structures that support channel blockade. The therapeutic opportunities afforded by these peptides are also highlighted. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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59
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Terragni B, Scalmani P, Franceschetti S, Cestèle S, Mantegazza M. Post-translational dysfunctions in channelopathies of the nervous system. Neuropharmacology 2017; 132:31-42. [PMID: 28571716 DOI: 10.1016/j.neuropharm.2017.05.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/12/2017] [Accepted: 05/26/2017] [Indexed: 12/23/2022]
Abstract
Channelopathies comprise various diseases caused by defects of ion channels. Modifications of their biophysical properties are common and have been widely studied. However, ion channels are heterogeneous multi-molecular complexes that are extensively modulated and undergo a maturation process comprising numerous steps of structural modifications and intracellular trafficking. Perturbations of these processes can give rise to aberrant channels that cause pathologies. Here we review channelopathies of the nervous system associated with dysfunctions at the post-translational level (folding, trafficking, degradation, subcellular localization, interactions with associated proteins and structural post-translational modifications). We briefly outline the physiology of ion channels' maturation and discuss examples of defective mechanisms, focusing in particular on voltage-gated sodium channels, which are implicated in numerous neurological disorders. We also shortly introduce possible strategies to develop therapeutic approaches that target these processes. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Benedetta Terragni
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Paolo Scalmani
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Silvana Franceschetti
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Sandrine Cestèle
- Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 06560, Valbonne-Sophia Antipolis, France; University Côte d'Azur (UCA), 06560, Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 06560, Valbonne-Sophia Antipolis, France; University Côte d'Azur (UCA), 06560, Valbonne-Sophia Antipolis, France.
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60
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Ion Channel Genes and Epilepsy: Functional Alteration, Pathogenic Potential, and Mechanism of Epilepsy. Neurosci Bull 2017; 33:455-477. [PMID: 28488083 DOI: 10.1007/s12264-017-0134-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 02/20/2017] [Indexed: 01/29/2023] Open
Abstract
Ion channels are crucial in the generation and modulation of excitability in the nervous system and have been implicated in human epilepsy. Forty-one epilepsy-associated ion channel genes and their mutations are systematically reviewed. In this paper, we analyzed the genotypes, functional alterations (funotypes), and phenotypes of these mutations. Eleven genes featured loss-of-function mutations and six had gain-of-function mutations. Nine genes displayed diversified funotypes, among which a distinct funotype-phenotype correlation was found in SCN1A. These data suggest that the funotype is an essential consideration in evaluating the pathogenicity of mutations and a distinct funotype or funotype-phenotype correlation helps to define the pathogenic potential of a gene.
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61
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Noebels J. Precision physiology and rescue of brain ion channel disorders. J Gen Physiol 2017; 149:533-546. [PMID: 28428202 PMCID: PMC5412535 DOI: 10.1085/jgp.201711759] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/24/2017] [Indexed: 11/20/2022] Open
Abstract
Ion channel genes, originally implicated in inherited excitability disorders of muscle and heart, have captured a major role in the molecular diagnosis of central nervous system disease. Their arrival is heralded by neurologists confounded by a broad phenotypic spectrum of early-onset epilepsy, autism, and cognitive impairment with few effective treatments. As detection of rare structural variants in channel subunit proteins becomes routine, it is apparent that primary sequence alone cannot reliably predict clinical severity or pinpoint a therapeutic solution. Future gains in the clinical utility of variants as biomarkers integral to clinical decision making and drug discovery depend on our ability to unravel complex developmental relationships bridging single ion channel structure and human physiology.
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Affiliation(s)
- Jeffrey Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030 .,Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
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62
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Oxidation of KCNB1 potassium channels triggers apoptotic integrin signaling in the brain. Cell Death Dis 2017; 8:e2737. [PMID: 28383553 PMCID: PMC5477583 DOI: 10.1038/cddis.2017.160] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/10/2017] [Accepted: 03/13/2017] [Indexed: 12/20/2022]
Abstract
Oxidative modification of the voltage-gated potassium (K+) channel KCNB1 promotes apoptosis in the neurons of cortex and hippocampus through a signaling pathway mediated by Src tyrosine kinases. How oxidation of the channel is transduced into Src recruitment and activation, however, was not known. Here we show that the apoptotic signal originates from integrins, which form macromolecular complexes with KCNB1 channels. The initial stimulus is transduced to Fyn and possibly other Src family members by focal adhesion kinase (FAK). Thus KCNB1 and integrin alpha chain V (integrin-α5) coimmunoprecipitated in the mouse brain and these interactions were retained upon channel's oxidation. Pharmacological inhibition of integrin signaling or FAK suppressed apoptosis induced by oxidation of KCNB1, as well as FAK and Src/Fyn activation. Most importantly, the activation of the integrin-FAK-Src/Fyn cascade was negligible in the presence of non-oxidizable C73A KCNB1 mutant channels, even though they normally interacted with integrin-α5. This leads us to conclude that the transition between the non-oxidized and oxidized state of KCNB1 activates integrin signaling. KCNB1 oxidation may favor integrin clustering, thereby facilitating the recruitment and activation of FAK and Src/Fyn kinases.
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63
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Parrini E, Marini C, Mei D, Galuppi A, Cellini E, Pucatti D, Chiti L, Rutigliano D, Bianchini C, Virdò S, De Vita D, Bigoni S, Barba C, Mari F, Montomoli M, Pisano T, Rosati A, Guerrini R. Diagnostic Targeted Resequencing in 349 Patients with Drug-Resistant Pediatric Epilepsies Identifies Causative Mutations in 30 Different Genes. Hum Mutat 2016; 38:216-225. [DOI: 10.1002/humu.23149] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 11/13/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Elena Parrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Carla Marini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Davide Mei
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Anna Galuppi
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Elena Cellini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Daniela Pucatti
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Laura Chiti
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Domenico Rutigliano
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Claudia Bianchini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Simona Virdò
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Dalila De Vita
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Stefania Bigoni
- UOL of Medical Genetics; Ferrara University Hospital; Ferrara Italy
| | - Carmen Barba
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Francesco Mari
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Martino Montomoli
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Tiziana Pisano
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Anna Rosati
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Department; A Meyer Children's Hospital; University of Florence; Florence Italy
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Latypova X, Matsumoto N, Vinceslas-Muller C, Bézieau S, Isidor B, Miyake N. Novel KCNB1 mutation associated with non-syndromic intellectual disability. J Hum Genet 2016; 62:569-573. [PMID: 27928161 DOI: 10.1038/jhg.2016.154] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/22/2016] [Accepted: 11/03/2016] [Indexed: 11/09/2022]
Abstract
Potassium voltage-gated channel subfamily B member 1 (KCNB1) encodes Kv2.1 potassium channel of crucial role in hippocampal neuron excitation homeostasis. KCNB1 mutations are known to cause early-onset infantile epilepsy. To date, 10 KCNB1 mutations have been described in 11 patients. Using whole-exome sequencing, we identified a novel de novo missense (c.1132G>C, p.V378L) KCNB1 mutation in a patient with global developmental delay, intellectual disability, severe speech impairment, but no episode of epilepsy until the lastly examined age of 6 years old. Furthermore, she showed neuropsychiatric symptoms including hyperactivity with irritability, heteroaggressiveness, psychomotor instability and agitation. Our observation might expand the phenotypic spectrum of KCNB1-related phenotypes and raises the issue of the occurrence of the epileptic phenotype.
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Affiliation(s)
- Xénia Latypova
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Cécile Vinceslas-Muller
- Service de Pédiatrie, Hôpital Mère-Enfant, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Stéphane Bézieau
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Bertrand Isidor
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France.,INSERM, UMR-957, Laboratoire de Physiopathologie de la Résorption Osseuse et thérapie des tumeurs osseuses primitives, Nantes, France
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
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65
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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66
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Naranjo D, Moldenhauer H, Pincuntureo M, Díaz-Franulic I. Pore size matters for potassium channel conductance. J Gen Physiol 2016; 148:277-91. [PMID: 27619418 PMCID: PMC5037345 DOI: 10.1085/jgp.201611625] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/10/2016] [Indexed: 01/31/2023] Open
Abstract
Ion channels are membrane proteins that mediate efficient ion transport across the hydrophobic core of cell membranes, an unlikely process in their absence. K+ channels discriminate K+ over cations with similar radii with extraordinary selectivity and display a wide diversity of ion transport rates, covering differences of two orders of magnitude in unitary conductance. The pore domains of large- and small-conductance K+ channels share a general architectural design comprising a conserved narrow selectivity filter, which forms intimate interactions with permeant ions, flanked by two wider vestibules toward the internal and external openings. In large-conductance K+ channels, the inner vestibule is wide, whereas in small-conductance channels it is narrow. Here we raise the idea that the physical dimensions of the hydrophobic internal vestibule limit ion transport in K+ channels, accounting for their diversity in unitary conductance.
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Affiliation(s)
- David Naranjo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Playa Ancha, Valparaíso 2360103, Chile
| | - Hans Moldenhauer
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Playa Ancha, Valparaíso 2360103, Chile
| | - Matías Pincuntureo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Playa Ancha, Valparaíso 2360103, Chile Programa de Doctorado en Ciencias, mención Biofísica y Biología Computacional, Universidad de Valparaíso, Valparaíso 2360103, Chile
| | - Ignacio Díaz-Franulic
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Playa Ancha, Valparaíso 2360103, Chile Center for Bioinformatics and Integrative Biology, Universidad Andrés Bello, Santiago 8370146, Chile Fraunhofer Chile Research, Las Condes 7550296, Chile
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67
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Jiang X, Lachance M, Rossignol E. Involvement of cortical fast-spiking parvalbumin-positive basket cells in epilepsy. PROGRESS IN BRAIN RESEARCH 2016; 226:81-126. [PMID: 27323940 DOI: 10.1016/bs.pbr.2016.04.012] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
GABAergic interneurons of the parvalbumin-positive fast-spiking basket cells subtype (PV INs) are important regulators of cortical network excitability and of gamma oscillations, involved in signal processing and cognition. Impaired development or function of PV INs has been associated with epilepsy in various animal models of epilepsy, as well as in some genetic forms of epilepsy in humans. In this review, we provide an overview of some of the experimental data linking PV INs dysfunction with epilepsy, focusing on disorders of the specification, migration, maturation, synaptic function, or connectivity of PV INs. Furthermore, we reflect on the potential therapeutic use of cell-type specific stimulation of PV INs within active networks and on the transplantation of PV INs precursors in the treatment of epilepsy and its comorbidities.
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Affiliation(s)
- X Jiang
- Université de Montréal, Montréal, QC, Canada; CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - M Lachance
- CHU Ste-Justine Research Center, Montréal, QC, Canada
| | - E Rossignol
- Université de Montréal, Montréal, QC, Canada; CHU Ste-Justine Research Center, Montréal, QC, Canada.
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