title: Investigation for RAPSN and DOK-7 mutations in a cohort of seronegative myasthenia gravis patients.
abstract: BACKGROUND
  Myasthenia gravis (MG) is an autoimmune disease. Patients without detectable antibodies against the nicotinic acetylcholine receptor or the muscle-specific tyrosine kinase are referred to as seronegative MG (SNMG). Because late-onset congenital myasthenic syndromes (CMSs) due to RAPSN or DOK7 mutations may be mistaken for SNMG, we investigated their frequency in a nationwide SNMG cohort.
  
  
  METHODS
  We performed sequencing of RAPSN and DOK7 in all Norwegian SNMG patients (n = 74) and 37 healthy controls, examining for the N88K and c.1124_1127dupTGCC mutations, respectively.
  
  
  RESULTS
  We found 1 patient homozygous for N88K and 2 carriers of the N88K mutation. Sequencing of DOK7 revealed no mutations.
  
  
  CONCLUSIONS
  This study confirms that rapsn CMS can be mistaken for SNMG. In addition, the frequency of rapsn CMS in our nationwide SNMG cohort was found to be low. SNMG patients with an atypical clinical presentation and pediatric cases should be tested for the N88K mutation before initiation of immunosuppressive drug treatment or thymectomy.
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway. espen.alseth@nevro.uib.no.
authors.forename: Espen Homleid
authors.initials: EH
authors.lastname: Alseth
authors.forename: Angelina Hatlø
authors.initials: AH
authors.lastname: Maniaol
authors.forename: Ahmed
authors.initials: A
authors.lastname: Elsais
authors.forename: Hanne Linda
authors.initials: HL
authors.lastname: Nakkestad
authors.forename: Chantal
authors.initials: C
authors.lastname: Tallaksen
authors.forename: Nils Erik
authors.initials: NE
authors.lastname: Gilhus
authors.forename: Geir Olve
authors.initials: GO
authors.lastname: Skeie
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D015331:Cohort Studies; D030561:Databases, Nucleic Acid; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D009157:Myasthenia Gravis / Q000097:blood* / Q000235:genetics*; D055815:Young Adult
chemical_list: C511692:DOK7 protein, human; D009124:Muscle Proteins; C051609:peripheral membrane protein 43K