title: Myoclonus in childhood-onset neurogenetic disorders: The importance of early identification and treatment.
abstract: BACKGROUND
  In clinical practice, myoclonus in childhood-onset neurogenetic disorders frequently remains unrecognized, because it is often overshadowed by other neurological features. Since treatment can lead to significant functional improvement, accurate phenotyping is essential. To demonstrate the importance of early identification and treatment, we report on four patients with various childhood-onset neurogenetic disorders suffering from myoclonus.
  
  
  METHODS
  We evaluated four patients with established childhood-onset neurogenetic disorders and involuntary jerky movements, who visited our young-onset movement disorder outpatient clinic.
  
  
  RESULTS
  We present the clinical data of four patients (aged 8-21 years) with childhood-onset neurogenetic disorders, including ataxia-telangiectasia, Coffin-Lowry syndrome and epileptic encephalopathy due to SCN1A mutations. All four suffered from jerky movements that hampered normal daily activities and that had gone unrecognized for several years. The presence of multifocal myoclonus was confirmed by polymyography. In all patients, treatment resulted in marked improvement of both myoclonus and overall functioning.
  
  
  CONCLUSIONS
  These cases highlight the relevance of actively searching for myoclonus in childhood-onset neurogenetic disorders, even when a molecular diagnosis has already been established. To further improve the awareness and recognition of myoclonus in children, we provide a list of childhood-onset neurogenetic disorders with myoclonus as important associated feature.
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands. Electronic address: m.e.van.egmond@umcg.nl.
authors.forename: Martje E
authors.initials: ME
authors.lastname: van Egmond
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands.
authors.forename: Jan Willem J
authors.initials: JW
authors.lastname: Elting
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands.
authors.forename: Anouk
authors.initials: A
authors.lastname: Kuiper
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands.
authors.forename: Rodi
authors.initials: R
authors.lastname: Zutt
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands.
authors.forename: Kirsten R
authors.initials: KR
authors.lastname: Heineman
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands.
authors.forename: Oebele F
authors.initials: OF
authors.lastname: Brouwer
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Pediatrics, Groningen, The Netherlands.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Sival
authors.affiliation: Radboud University Medical Center, Department of Pediatric Neurology, Nijmegen, The Netherlands.
authors.forename: Michel A
authors.initials: MA
authors.lastname: Willemsen
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, The Netherlands.
authors.forename: Marina A J
authors.initials: MA
authors.lastname: Tijssen
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Pediatrics, Groningen, The Netherlands; University of Groningen, University Medical Center Groningen, Department of Genetics, Groningen, The Netherlands.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: de Koning
mesh_terms: D000927:Anticonvulsants / Q000627:therapeutic use; D001260:Ataxia Telangiectasia / Q000209:etiology / Q000235:genetics; D001927:Brain Diseases / Q000150:complications / Q000235:genetics; D002648:Child; D038921:Coffin-Lowry Syndrome / Q000209:etiology / Q000235:genetics; D042241:Early Diagnosis; D004576:Electromyography; D004831:Epilepsies, Myoclonic / Q000235:genetics; D004827:Epilepsy / Q000209:etiology / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D009069:Movement Disorders / Q000209:etiology / Q000235:genetics; D009207:Myoclonus / Q000188:drug therapy / Q000209:etiology*; D062550:NAV1.1 Voltage-Gated Sodium Channel / Q000235:genetics; D009422:Nervous System Diseases / Q000150:complications* / Q000188:drug therapy / Q000235:genetics*; D055815:Young Adult
chemical_list: D000927:Anticonvulsants; D062550:NAV1.1 Voltage-Gated Sodium Channel; C568242:SCN1A protein, human
keywords: Movement disorders; Myoclonus; Neurogenetic disorders