Abstract

Epileptic encephalopathies are a phenotypically and genetically heterogeneous group of severe epilepsies accompanied by intellectual disability and other neurodevelopmental features1,2,3,4,5,6. Using next-generation sequencing, we identified four different de novo mutations in KCNA2, encoding the potassium channel KV1.2, in six isolated patients with epileptic encephalopathy (one mutation recurred three times independently). Four individuals presented with febrile and multiple afebrile, often focal seizure types, multifocal epileptiform discharges strongly activated by sleep, mild to moderate intellectual disability, delayed speech development and sometimes ataxia. Functional studies of the two mutations associated with this phenotype showed almost complete loss of function with a dominant-negative effect. Two further individuals presented with a different and more severe epileptic encephalopathy phenotype. They carried mutations inducing a drastic gain-of-function effect leading to permanently open channels. These results establish KCNA2 as a new gene involved in human neurodevelopmental disorders through two different mechanisms, predicting either hyperexcitability or electrical silencing of KV1.2-expressing neurons.

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Acknowledgements

We thank all patients and family members for their participation in this study, S. Grissmer (Ulm University) for providing the human cDNA clone of KCNA2, and F. Lang and his colleagues (University of Tübingen) for providing Xenopus oocytes. J.R.L. (32EP30_136042/1), J.M.S. (EUI-EURC2011-4325), H. Lerche (DFG Le1030/11-1), P.D.J. (G.A.136.11.N, FWO/ESF-ECRP), H.S.C. (TUBITAK 110S518) and I.H. (DFG HE 5415 3-1) received financial support within the EuroEPINOMICS RES and EuroEPINOMICS CoGIE networks (http://www.euroepinomics.org/), a Eurocores project of the European Science Foundation. R.S. received funding from the European Union (E-Rare JTC grants 01GM1408B and PIOF-GA-2012-326681). J.M.S. received further support from the Ministerio de Economía y Competitividad (SAF2010-18586). H. Lerche, S.B. and S. Maljevic received further support from the Federal Ministry for Education and Research (BMBF, program on rare diseases, IonNeurONet: 01GM1105A). S.Z. received support from the US National Institutes of Health (R01NS072248). S.M.S. received support from the Wellcome Trust (084730), National Institute for Health Research (NIHR) University College London Hospital Biomedical Research Centre and Epilepsy Society, UK. M. Synofzik received support from the Interdisciplinary Center for Clinical Research (IZKF) Tübingen (2191-0-0). A.S. received funding for a postdoctoral fellowship from the Fonds Wetenschappelijk Onderzoek. T. Djémié is a PhD fellow of the Institute of Science and Technology (IWT).

Author information

Author notes

    • Steffen Syrbe
    • , Ulrike B S Hedrich
    • , Erik Riesch
    •  & Tania Djémié

    These authors contributed equally to this work.

    • Johannes R Lemke
    • , Holger Lerche
    • , Sarah Weckhuysen
    • , Holger Lerche
    •  & Johannes R Lemke

    These authors jointly supervised this work.

Affiliations

  1. Department of Women and Child Health, Hospital for Children and Adolescents, University of Leipzig, Leipzig, Germany.

    • Steffen Syrbe
    • , Astrid Bertsche
    • , Matthias K Bernhard
    • , Andreas Merkenschlager
    • , Wieland Kiess
    •  & Johannes R Lemke
  2. Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.

    • Ulrike B S Hedrich
    • , Stephan Müller
    • , Heidrun Löffler
    • , Katja Detert
    • , Yvonne G Weber
    • , Holger Lerche
    •  & Snezana Maljevic
  3. Center for Genomics and Transcriptomics (CeGaT), Tübingen, Germany.

    • Erik Riesch
    •  & Saskia Biskup
  4. Division of Human Genetics, University Children's Hospital Inselspital, Bern, Switzerland.

    • Erik Riesch
    • , Sabina Gallati
    •  & Johannes R Lemke
  5. Swiss Epilepsy Center, Zürich, Switzerland.

    • Erik Riesch
    • , Thomas Dorn
    • , Heinrich Vogt
    •  & Günter Krämer
  6. Neurogenetics Group, Department of Molecular Genetics, VIB, Antwerp, Belgium.

    • Tania Djémié
    • , Peter De Jonghe
    • , Arvid Suls
    •  & Sarah Weckhuysen
  7. Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium.

    • Tania Djémié
    • , Peter De Jonghe
    • , Arvid Suls
    •  & Sarah Weckhuysen
  8. Danish Epilepsy Center, Dianalund, Denmark.

    • Rikke S Møller
    •  & Helle Hjalgrim
  9. Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark.

    • Rikke S Møller
  10. Department of Clinical and Experimental Epilepsy, University College London Institute of Neurology, Queen Square, London, UK.

    • Bridget Maher
    • , Laura Hernandez-Hernandez
    •  & Sanjay M Sisodiya
  11. Epilepsy Society, Chalfont-St-Peter, Bucks, UK.

    • Bridget Maher
    • , Laura Hernandez-Hernandez
    •  & Sanjay M Sisodiya
  12. Department of Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.

    • Matthis Synofzik
    • , Ludger Schöls
    •  & Rebecca Schüle
  13. German Research Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany.

    • Matthis Synofzik
    • , Ludger Schöls
    •  & Rebecca Schüle
  14. Department of Molecular Biology and Genetics, Boǧaziçi University, Istanbul, Turkey.

    • Hande S Caglayan
  15. Division of Child Neurology, Gulhane Military Medical School, Ankara, Turkey.

    • Mutluay Arslan
  16. Neurology Laboratory and Epilepsy Unit, Department of Neurology, Instituto de Investigatión Sanitaria–Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Madrid, Spain.

    • José M Serratosa
  17. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.

    • José M Serratosa
  18. Cologne Center for Genomics, University of Cologne, Cologne, Germany.

    • Michael Nothnagel
  19. Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg.

    • Patrick May
    • , Roland Krause
    •  & Rudi Balling
  20. Division of Pediatric Endocrinology, University Children's Hospital Inselspital, Bern, Switzerland.

    • Primus E Mullis
  21. Department of Pediatric Neurology, Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

    • Tarja Linnankivi
  22. Folkhälsan Institute of Genetics, Helsinki, Finland.

    • Anna-Elina Lehesjoki
  23. Neuroscience Center, University of Helsinki, Helsinki, Finland.

    • Anna-Elina Lehesjoki
  24. Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland.

    • Anna-Elina Lehesjoki
  25. Department of Child Neurology, 2nd Faculty of Medicine, Charles University, Motol Hospital, Prague, Czech Republic.

    • Katalin Sterbova
    •  & Vladimir Komarek
  26. Pediatric Neurology Clinic II, Department of Neurology, Pediatric Neurology, Psychiatry and Neurosurgery, ‘Carol Davila’ University of Medicine, Bucharest, Romania.

    • Dana C Craiu
  27. Pediatric Neurology Clinic, ‘Professor Doctor Alexandru Obregia’ Clinical Hospital, Bucharest, Romania.

    • Dana C Craiu
  28. Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland.

    • Dorota Hoffman-Zacharska
  29. Child and Adolescent Department, Pediatric Neurology, University Hospitals, Geneva, Switzerland.

    • Christian M Korff
  30. Division of Neuropediatrics, University Children's Hospital Inselspital, Bern, Switzerland.

    • Maja Steinlin
  31. Dr. J.T. MacDonald Department for Human Genetics, Hussman Institute for Human Genomics, University of Miami, Miami, Florida, USA.

    • Michael Gonzalez
    • , Stephan Züchner
    •  & Rebecca Schüle
  32. Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland.

    • Aarno Palotie
  33. Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK.

    • Padhraig Gormley
    •  & Aarno Palotie
  34. Psychiatric and Neurodevelopmental Genetics Unit, Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA.

    • Aarno Palotie
  35. Department of Neurology, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium.

    • Peter De Jonghe
  36. Department of Neuropediatrics, Christian Albrechts University of Kiel, Kiel, Germany.

    • Ingo Helbig
    • , Johanna Jähn
    • , Hiltrud Muhle
    • , Ulrich Stephani
    •  & Sarah von Spiczak
  37. Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.

    • Ingo Helbig
  38. Department of Neuropediatrics, University of Tübingen, Tübingen, Germany.

    • Markus Wolff
  39. Department of Neurology, University of Tübingen, Tübingen, Germany.

    • Holger Lerche
  40. Institute of Human Genetics, University of Leipzig, Leipzig, Germany.

    • Johannes R Lemke
  41. Department of Paediatrics, University of Zagreb, Medical School, University Hospital Centre Zagreb, Zagreb, Croatia.

    • Nina Barisic
  42. INSERM UMR 975, Institut du Cerveau et de la Moelle Epinière, Hôpital Pitié-Salpêtrière, Paris, France.

    • Stéphanie Baulac
    • , Christel Depienne
    •  & Eric LeGuern
  43. CNRS 7225, Hôpital Pitié-Salpêtrière, Paris, France.

    • Stéphanie Baulac
    •  & Eric LeGuern
  44. Université Pierre et Marie Curie–Paris 6 (UPMC), UMRS 975, Paris, France.

    • Stéphanie Baulac
    • , Christel Depienne
    •  & Eric LeGuern
  45. Institut für Humangenetik, Universität Würzburg, Würzburg, Germany.

    • Christel Depienne
  46. Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer, University of Florence, Florence, Italy.

    • Renzo Guerrini
    •  & Carla Marini
  47. Epilepsy Center Hessen, Department of Neurology, University Hospitals Marburg and Philipps, University Marburg, Marburg, Germany.

    • Karl Martin Klein
    •  & Felix Rosenow
  48. Department of Medical Genetics, University Medical Center Utrecht, Utrecht, the Netherlands.

    • Bobby P C Koeleman
  49. Assistance Publique–Hôpitaux de Paris (AP-HP), Hôpital Pitié-Salpêtrière, Département de Génétique et de Cytogénétique, Unité Fonctionnelle de Neurogénétique Moléculaire et Cellulaire, Paris, France.

    • Eric LeGuern
  50. Department of Clinical Neuroscience, Institute of Psychiatry, King's College London, London, UK.

    • Deb Pal
  51. Department of Medical Genetics, Oslo University Hospital, Oslo, Norway.

    • Kaja Selmer
  52. Institute of Medical Genetics, University of Oslo, Oslo, Norway.

    • Kaja Selmer
  53. Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, ‘G Gaslini Institute’, Genova, Italy.

    • Pasquale Striano
  54. Department of Pediatrics, University of Tartu, Tartu, Estonia.

    • Tiina Talvik
  55. Department of Neurology and Neurorehabilitation, Children's Clinic, Tartu University Hospital, Tartu, Estonia.

    • Tiina Talvik
  56. Laboratory of Neurogenetics, Department of Neurosciences, Gaslini Institute, Genova, Italy.

    • Federico Zara

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Contributions

Study design: S.S., U.B.S.H., S.W., H. Lerche and J.R.L. Subject ascertainment and phenotyping: S.S., E.R., R.S.M., B.M., L.H.-H., H.S.C., M.A., J.M.S., T. Dorn, H.V., G.K., M. Synofzik, L.S., P.E.M., T.L., A.-E.L., K.S., D.C.C., D.H.-Z., C.M.K., Y.G.W., M. Steinlin, S.G., A.B., M.K.B., A.M., W.K., A.P., A.S., P.D.J., I.H., S.B., M.W., S.M.S., S.W., H. Lerche, J.R.L. and the EuroEPINOMICS RES Consortium. Mutation and CNV analysis: E.R., T. Djémié, B.M., L.H.-H., R.S., M.G., S.Z., A.S., P.D.J., S.B., S.M.S., S.W., H. Lerche and J.R.L. Statistical analysis: M.N., P.M., R.K., H. Lerche and J.R.L. Functional analysis: U.B.S.H., S. Müller, H. Löffler, K.D., S. Maljevic and H. Lerche. Interpretation of data: S.S., U.B.S.H., M.W., S. Maljevic, S.M.S., S.W., H. Lerche and J.R.L. Writing of the manuscript: S.S., U.B.S.H., T. Djémié, M.N., P.M., S. Maljevic, S.M.S., S.W., H. Lerche and J.R.L. Revision of the manuscript: all authors.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Johannes R Lemke or Holger Lerche or Holger Lerche or Johannes R Lemke.

Integrated supplementary information

Supplementary information

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  1. 1.

    Supplementary Text and Figures

    Supplementary Figures 1–5 and Supplementary Note.

Excel files

  1. 1.

    Supplementary Table 1

    List of all variants detected in patients 1, 3 and 5 by panel analysis.

  2. 2.

    Supplementary Table 2

    Prediction of the pathogenicity of all KCNA2 variants detected within this study as well as of all nonsynonymous KCNA2 variants reported in the ExAC database.

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DOI

https://doi.org/10.1038/ng.3239

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