Cited by 164Epilepsy research and treatmentIon channel regulation and functionCardiac electrophysiology and arrhythmias

Clinical spectrum and genotype–phenotype associations of KCNA2-related encephalopathies

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Masnada, Silvia, Hedrich, Ulrike B S, Gardella, Elena, Schubert, Julian, Kaiwar, Charu, Klee, Eric W, Lanpher, Brendan C, Gavrilova, Ralitza H +35 more·2017·Brain

Abstract

Recently, de novo mutations in the gene KCNA2, causing either a dominant-negative loss-of-function or a gain-of-function of the voltage-gated K+ channel Kv1.2, were described to cause a new molecular entity within the epileptic encephalopathies. Here, we report a cohort of 23 patients (eight previously described) with epileptic encephalopathy carrying either novel or known KCNA2 mutations, with the aim to detail the clinical phenotype associated with each of them, to characterize the functional effects of the newly identified mutations, and to assess genotype-phenotype associations. We identified five novel and confirmed six known mutations, three of which recurred in three, five and seven patients, respectively. Ten mutations were missense and one was a truncation mutation; de novo occurrence could be shown in 20 patients. Functional studies using a Xenopus oocyte two-microelectrode voltage clamp system revealed mutations with only loss-of-function effects (mostly dominant-negative current amplitude reduction) in eight patients or only gain-of-function effects (hyperpolarizing shift of voltage-dependent activation, increased amplitude) in nine patients. In six patients, the gain-of-function was diminished by an additional loss-of-function (gain-and loss-of-function) due to a hyperpolarizing shift of voltage-dependent activation combined with either decreased amplitudes or an additional hyperpolarizing shift of the inactivation curve. These electrophysiological findings correlated with distinct phenotypic features. The main differences were (i) predominant focal (loss-of-function) versus generalized (gain-of-function) seizures and corresponding epileptic discharges with prominent sleep activation in most cases with loss-of-function mutations; (ii) more severe epilepsy, developmental problems and ataxia, and atrophy of the cerebellum or even the whole brain in about half of the patients with gain-of-function mutations; and (iii) most severe early-onset phenotypes, occasionally with neonatal onset epilepsy and developmental impairment, as well as generalized and focal seizures and EEG abnormalities for patients with gain- and loss-of-function mutations. Our study thus indicates well represented genotype-phenotype associations between three subgroups of patients with KCNA2 encephalopathy according to the electrophysiological features of the mutations.

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  1. [11]11. Epi4K Consortium & Epilepsy Phenome/Genome Project. De novo mutations in epileptic encephalopathies. Nature 2013; 501, 217-21.

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Authors
Masnada, S., Hedrich, U. B. S., Gardella, E., Schubert, J., Kaiwar, C., Klee, E. W., Lanpher, B. C., Gavrilova, R. H., Synofzik, M., Bast, T., Gorman, K., King, M. D., Allen, N. M., Conroy, J., Ben Zeev, B., Tzadok, M., Korff, C., Dubois, F., Ramsey, K., Narayanan, V., Serratosa, J. M., Giraldez, B. G., Helbig, I., Marsh, E., O’Brien, M., Bergqvist, C. A., Binelli, A., Porter, B., Zaeyen, E., Horovitz, D. D., Wolff, M., Marjanovic, D., Caglayan, H. S., Arslan, M., Pena, S. D. J., Sisodiya, S. M., Balestrini, S., Syrbe, S., Veggiotti, P., Lemke, J. R., Møller, R. S., Lerche, H., & Rubboli, G.
Affiliations
  • University of Pavia (IT)
  • Hertie Institute for Clinical Brain Research (DE)
  • University of Southern Denmark (DK)
  • Mayo Clinic (US)
  • German Center for Neurodegenerative Diseases (DE)
  • Diakonie Kork (DE)
  • University College Dublin (IE)
  • Sackler school of medicine Tel Aviv University, Tel Aviv, Israel
  • Sheba Medical Center (IL)
  • University Hospital of Geneva (CH)
  • Centre Hospitalier Universitaire de Grenoble (FR)
  • Translational Genomics Research Institute (US)
  • Neurology Laboratory and Epilepsy Unit, Department of Neurology, IIS- Fundación Jiménez Díaz, UAM, Madrid, Spain
  • Children's Hospital of Philadelphia (US)
  • Hospital Pedro de Elizalde (AR)
  • Stanford University (US)
  • Neuropediatrics Committee of State of Rio De Janeiro, Rio De Janeiro, Brazil
  • Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira (BR)
  • University Children's Hospital Tübingen (DE)
  • Danish Epilepsy Centre, Dianalund, Denmark
  • Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
  • Department of Pediatric Neurology, Gulhane Military Medical School, Ankara, Turkey
  • GENE – Núcleo de Genética Médica, Belo Horizonte, MG, Brazil
  • UCL Queen Square Institute of Neurology (GB)
  • University Hospital Heidelberg (DE)
  • University Hospital Leipzig (DE)
  • University of Copenhagen (DK)
Corresponding author
Rubboli, Guido
Venue
Brain
Published
2017-08-24
Volume
140
Issue
9
Pages
2337-2354
ISSN
  • 0006-8950 (ISSN-L)
  • 1460-2156
OpenAlex
W2749761816
Cited by
164
References
42
Citations by year
2026: 12 · 2025: 15 · 2024: 29 · 2023: 20 · 2022: 18 · 2021: 23 · 2020: 22 · 2019: 12 · 2018: 13
FWCI
10.56
Type
journal article
Language
en
Licence
other-oa
Locations
  • Brain (publishedVersion)
  • PubMed (publishedVersion)
  • Archive ouverte UNIGE (University of Geneva) (publishedVersion)
  • University of Southern Denmark Research Portal (University of Southern Denmark) (submittedVersion, other-oa)
  • UCL Discovery (University College London) (submittedVersion)
  • Florence Research (University of Florence) (submittedVersion)
  • DZNE Pub (submittedVersion)
  • Research at the University of Copenhagen (University of Copenhagen) (submittedVersion)
  • Archive ouverte UNIGE (University of Geneva) (submittedVersion, cc-by)
Funders
  • German Research Foundation (HE5415/3‐1, DFG, HE5415/5‐1, HE5415/6‐1)
  • European Science Foundation (Le1030/11‐2)
Topics
  • Health Sciences › Medicine › Psychiatry and Mental health › Epilepsy research and treatment
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Ion channel regulation and function
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac electrophysiology and arrhythmias
Keywords
KCNA2, epileptic encephalopathy, genotype-phenotype correlation, de novo mutations, loss-of-function mutations, gain-of-function mutations, dominant negative effect, developmental disabilities, cerebellar atrophy, neonatal-onset epilepsy, EEG abnormalities
MeSH terms
Animals, Brain Diseases, Epilepsy, Mutation, Oocytes, Phenotype, Xenopus, Kv1.2 Potassium Channel, Genetic Association Studies

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