title: Homozygous mutation in TXNRD1 is associated with genetic generalized epilepsy.
abstract: Increased oxidative stress has been widely implicated in the pathogenesis in various forms of human epilepsy. Here, we report a homozygous mutation in TXNRD1 (thioredoxin reductase 1) in a family with genetic generalized epilepsy. TXNRD1 is an essential selenium-containing enzyme involved in detoxification of reactive oxygen species (ROS) and redox signaling. The TXNRD1 mutation p.Pro190Leu affecting a highly conserved amino acid residue was identified by whole-exome sequencing of blood DNA from the index patient. The detected mutation and its segregation within the family - all siblings of the index patient were homozygous and the parents heterozygous - were confirmed by Sanger sequencing. TXNRD1 activity was determined in subcellular fractions from a skeletal muscle biopsy and skin fibroblasts of the index patient and the expression levels of the mutated protein were assessed by75Se labeling and Western blot analysis. As result of the mutation, the activity of TXNRD1 was reduced in the patient's fibroblasts and skeletal muscle (to 34±3% and 16±8% of controls, respectively). In fibroblasts, we detected reduced75Se-labeling of the enzyme (41±3% of controls). An in-depth in vitro kinetic analysis of the recombinant mutated TXNRD1 indicated 30-40% lowered kcat/Se values. Therefore, a reduced activity of the enzyme in the patient's tissue samples is explained by (i) lower enzyme turnover and (ii) reduced abundance of the mutated enzyme as confirmed by Western blotting and75Se labeling. The mutant fibroblasts were also found to be less resistant to a hydrogen peroxide challenge. Our data agree with a potential role of insufficient ROS detoxification for disease manifestation in genetic generalized epilepsy.
authors.affiliation: Department of Epileptology and Life & Brain Center, University of Bonn, Bonn, Germany. Electronic address: alexei_kudin@yahoo.com.
authors.forename: Alexei P
authors.initials: AP
authors.lastname: Kudin
authors.affiliation: Department of Epileptology and Life & Brain Center, University of Bonn, Bonn, Germany. Electronic address: brain21@gmx.net.
authors.forename: Gregor
authors.initials: G
authors.lastname: Baron
authors.affiliation: Department of Epileptology and Life & Brain Center, University of Bonn, Bonn, Germany. Electronic address: gabor.zsurka@ukb.uni-bonn.de.
authors.forename: Gábor
authors.initials: G
authors.lastname: Zsurka
authors.affiliation: Department of Epileptology and Life & Brain Center, University of Bonn, Bonn, Germany. Electronic address: kevin.hampel@gmx.de.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Hampel
authors.affiliation: Department of Epileptology and Life & Brain Center, University of Bonn, Bonn, Germany. Electronic address: christian.elger@ukb.uni-bonn.de.
authors.forename: Christian E
authors.initials: CE
authors.lastname: Elger
authors.affiliation: Department of Neurosurgery, University of Bonn, Bonn, Germany. Electronic address: alexander.grote@ukb.uni-bonn.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Grote
authors.affiliation: Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany. Electronic address: yvonne.weber@uni-tuebingen.de.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Weber
authors.affiliation: Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany. Electronic address: holger.lerche@uni-tuebingen.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Lerche
authors.affiliation: Cologne Center for Genomics, University of Cologne, Cologne, Germany. Electronic address: holger.thiele@uni-koeln.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Thiele
authors.affiliation: Cologne Center for Genomics, University of Cologne, Cologne, Germany. Electronic address: nuernberg@uni-koeln.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Nürnberg
authors.affiliation: Cologne Center for Genomics, University of Cologne, Cologne, Germany. Electronic address: herbert.schulz@uni-koeln.de.
authors.forename: Herbert
authors.initials: H
authors.lastname: Schulz
authors.affiliation: Cologne Center for Genomics, University of Cologne, Cologne, Germany.
authors.forename: Ann-Kathrin
authors.initials: AK
authors.lastname: Ruppert
authors.affiliation: Cologne Center for Genomics, University of Cologne, Cologne, Germany. Electronic address: sandert@uni-koeln.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Sander
authors.affiliation: Division of Biochemistry, Dept. Medical Biochemistry and Biophysics (MBB), Karolinska Institutet, Stockholm, Sweden. Electronic address: Qing.Cheng@ki.se.
authors.forename: Qing
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: Division of Biochemistry, Dept. Medical Biochemistry and Biophysics (MBB), Karolinska Institutet, Stockholm, Sweden. Electronic address: elias.arner@ki.se.
authors.forename: Elias Sj
authors.initials: ES
authors.lastname: Arnér
authors.affiliation: Institute of Experimental Endocrinology, Charité-Universitätsmedizin, Berlin, Germany. Electronic address: lutz.schomburg@charite.de.
authors.forename: Lutz
authors.initials: L
authors.lastname: Schomburg
authors.affiliation: Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany. Electronic address: seeher@gmx.de.
authors.forename: Sandra
authors.initials: S
authors.lastname: Seeher
authors.affiliation: Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany. Electronic address: nfradejas@uni-bonn.de.
authors.forename: Noelia
authors.initials: N
authors.lastname: Fradejas-Villar
authors.affiliation: Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany. Electronic address: uschweiz@uni-bonn.de.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schweizer
authors.affiliation: Department of Epileptology and Life & Brain Center, University of Bonn, Bonn, Germany. Electronic address: wolfram.kunz@ukb.uni-bonn.de.
authors.forename: Wolfram S
authors.initials: WS
authors.lastname: Kunz
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004829:Epilepsy, Generalized / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D020022:Genetic Predisposition to Disease; D005978:Glutathione / Q000378:metabolism; D006720:Homozygote; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009154:Mutation; D018384:Oxidative Stress / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D054481:Thioredoxin Reductase 1 / Q000235:genetics*; D000073359:Exome Sequencing
chemical_list: D017382:Reactive Oxygen Species; C516124:TXNRD1 protein, human; D054481:Thioredoxin Reductase 1; D005978:Glutathione
keywords: Epilepsy; Generalized seizures; Oxidative stress; TXNRD1