2. Academic Validation
  3. Variant Intestinal-Cell Kinase in Juvenile Myoclonic Epilepsy

Variant Intestinal-Cell Kinase in Juvenile Myoclonic Epilepsy

  • N Engl J Med. 2018 Mar 15;378(11):1018-1028. doi: 10.1056/NEJMoa1700175.
Julia N Bailey 1,  Laurence de Nijs 1,  Dongsheng Bai 1,  Toshimitsu Suzuki 1,  Hiroyuki Miyamoto 1,  Miyabi Tanaka 1,  Christopher Patterson 1,  Yu-Chen Lin 1,  Marco T Medina 1,  María E Alonso 1,  José M Serratosa 1,  Reyna M Durón 1,  Viet H Nguyen 1,  Jenny E Wight 1,  Iris E Martínez-Juárez 1,  Adriana Ochoa 1,  Aurelio Jara-Prado 1,  Laura Guilhoto 1,  Yolly Molina 1,  Elsa M Yacubian 1,  Minerva López-Ruiz 1,  Yushi Inoue 1,  Sunao Kaneko 1,  Shinichi Hirose 1,  Makiko Osawa 1,  Hirokazu Oguni 1,  Shinji Fujimoto 1,  Thierry M Grisar 1,  John M Stern 1,  Kazuhiro Yamakawa 1,  Bernard Lakaye 1,  Antonio V Delgado-Escueta 1
Affiliations

Affiliation

  • 1 From the Epilepsy Genetics-Genomics Lab, Neurology and Research Services, Veterans Affairs Greater Los Angeles Healthcare System (J.N.B., D.B., M.T., C.P., Y.-C.L., J.M. Serratosa, R.M.D., V.H.N., J.E.W., A.V.D.-E.), the Department of Neurology, David Geffen School of Medicine at UCLA (D.B., M.T., J.M. Serratosa, J.M. Stern, A.V.D.-E.), and the Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles (J.N.B.), Los Angeles, and Chapman University, Irvine (V.H.N.) - all in California; Grappe Interdisciplinaire de Génoprotéomique Appliquée Neurosciences, University of Liege, Liege, Belgium (L.N., T.M.G., B.L.); RIKEN Brain Science Institute, Saitama (T.S., H.M., K.Y.), Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka (Y.I.), Hirosaki University Graduate School of Medicine, Hirosaki (S.K.), Fukuoka University, Fukuoka (S.H.), Tokyo Women's Medical University, Tokyo (M.O., H.O.), Nagoya City University, Nagoya (S.F.), and Tsutsujigaoka Children's Clinic, Aichi (S.F.) - all in Japan; National Autonomous University of Honduras (M.T.M., Y.M.) and Universidad Tecnológica Centroamericana (R.M.D.), Tegucigalpa; National Institute of Neurology and Neurosurgery Manuel Velasco Suarez (M.E.A., I.E.M.-J., A.O., A.J.-P.) and General Hospital of Mexico (M.L.-R.), Mexico City; Universidade Federal de São Paulo, São Paulo (L.G., E.M.Y.); and the Instituto de Investigación Sanitaria-Jiménez Díaz Foundation, Autonomous University of Madrid and Biomedical Research Network Center on Rare Diseases, Madrid (J.M. Serratosa).
PMID: 29539279 DOI: 10.1056/NEJMoa1700175
Abstract

Background: In juvenile myoclonic epilepsy, data are limited on the genetic basis of networks promoting convulsions with diffuse polyspikes on electroencephalography (EEG) and the subtle microscopic brain dysplasia called microdysgenesis.

Methods: Using Sanger Sequencing, we sequenced the exomes of six members of a large family affected with juvenile myoclonic epilepsy and confirmed cosegregation in all 37 family members. We screened an additional 310 patients with this disorder for variants on DNA melting-curve analysis and targeted real-time DNA Sequencing of the gene encoding intestinal-cell kinase ( ICK). We calculated Bayesian logarithm of the odds (LOD) scores for cosegregating variants, odds ratios in case-control associations, and allele frequencies in the Genome Aggregation Database. We performed functional tests of the effects of variants on mitosis, Apoptosis, and radial neuroblast migration in vitro and conducted video-EEG studies in mice lacking a copy of Ick.

Results: A variant, K305T (c.914A→C), cosegregated with epilepsy or polyspikes on EEG in 12 members of the family affected with juvenile myoclonic epilepsy. We identified 21 pathogenic ICK variants in 22 of 310 additional patients (7%). Four strongly linked variants (K220E, K305T, A615T, and R632X) impaired mitosis, cell-cycle exit, and radial neuroblast migration while promoting Apoptosis. Tonic-clonic convulsions and polyspikes on EEG resembling seizures in human juvenile myoclonic epilepsy occurred more often in knockout heterozygous mice than in wild-type mice (P=0.02) during light sleep with isoflurane anesthesia.

Conclusions: Our data provide evidence that heterozygous variants in ICK caused juvenile myoclonic epilepsy in 7% of the patients included in our analysis. Variant ICK affects cell processes that help explain microdysgenesis and polyspike networks observed on EEG in juvenile myoclonic epilepsy. (Funded by the National Institutes of Health and Others.).

Figures