title: How common is childhood myasthenia? The UK incidence and prevalence of autoimmune and congenital myasthenia.
abstract: OBJECTIVE
  To ascertain the frequency of childhood myasthenia in the UK. Specifically, we aimed to identify the detected incidence of autoimmune myasthenia and the detected prevalence of genetically confirmed congenital myasthenic syndrome (CMS) in children.
  
  
  METHODS
  All children under 18 years of age on 31 December 2009 with a confirmed CMS genetic mutation were identified by the only UK laboratory undertaking CMS genetic testing. All cases with positive acetylcholine receptor (AChR) and muscle specific kinase (MuSK) receptor antibodies in the 5 years between 2003 and 2007 inclusive were identified by the testing laboratories. UK census data from 2001 were used as the denominator for analyses.
  
  
  RESULTS
  The UK detected prevalence of genetically confirmed CMS was 9.2 per million children under 18 years of age. CMS was equally prevalent in girls and boys. CHRNE, RAPSN and DOK7 were the most commonly identified mutations. Prevalence varied across geographical regions in England (between 2.8 and 14.8 per million children). The mean incidence of antibody-positive autoimmune myasthenia was 1.5 per million children per year over the period of the study. Girls were affected more frequently than boys; this difference persisted across the age range. Antibodies were identified during the neonatal period in 17 children.
  
  
  CONCLUSIONS
  This laboratory based study shows that childhood myasthenia is very rare. This condition is treatable, and these definitive detected incidence and prevalence data can be used to help plan diagnostic and supporting services for affected children and their families, and maximise research opportunities.
authors: Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, UK Department of Paediatrics, University of Oxford, Oxford, UK.
authors: Jeremy Ross
authors: JR
authors: Parr
authors: Department of Paediatrics, University of Oxford, Oxford, UK.
authors: Morag Jane
authors: MJ
authors: Andrew
authors: Department of Paediatrics, University of Oxford, Oxford, UK.
authors: Maria
authors: M
authors: Finnis
authors: The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors: David
authors: D
authors: Beeson
authors: The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors: Angela
authors: A
authors: Vincent
authors: Department of Paediatrics, University of Oxford, Oxford, UK.
authors: Sandeep
authors: S
authors: Jayawant
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D009154:Mutation; D020294:Myasthenic Syndromes, Congenital / Q000453:epidemiology* / Q000235:genetics / Q000276:immunology; D015995:Prevalence; D006113:United Kingdom / Q000453:epidemiology
keywords: Epidemiology; Neurology; Neuromuscular