title: Vestibular dysfunction is a clinical feature of the Jervell and Lange-Nielsen Syndrome.
abstract: OBJECTIVE
  To investigate the possible association between Jervell and Lange-Nielsen Syndrome (JLNS) genotype and vestibular dysfunction.
  
  
  METHODS
  In 15 cases with JLNS, clinical data obtained from a semi-structured interview and full medical records were reviewed and post-rotatory nystagmus testing was performed.
  
  
  RESULTS
  All genotyped cases (n = 14) had double KCNQ1 mutations. Symptoms of impaired balance were reported in 14/14 deaf JLNS cases. Gross motor developmental delay (not walking without support at 18 months of age) was seen in 11/12 cases with available data (mean age for walking: 24 months). A pathologic post-rotatory test was seen in 9/9 tested subjects, and in 3 subjects clinical testing had been performed showing complete lack of vestibular function. Vestibular dysfunction was seen in deaf JLNS cases with (n = 5) and without (n = 9) cochlear implants, including subjective symptoms (5/5 vs. 9/9) and gross motor developmental delay (5/5 vs. 6/8).
  
  
  CONCLUSIONS
  We identified a high frequency of symptoms and signs associated with vestibular dysfunction in deaf JLNS cases, irrespective of previous cochlear implantation. Disruption of endolymph homeostasis in the inner ear, including cochlea and vestibular system, by profound KCNQ1 function loss is the proposed mechanism.
authors.affiliation: Department of Clinical Sciences, Pediatrics, Umeå University , Umeå , Sweden.
authors.forename: Annika
authors.initials: A
authors.lastname: Winbo
authors.forename: Annika
authors.initials: A
authors.lastname: Rydberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D019929:Cochlear Implantation; D003638:Deafness / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology / Q000628:therapy; D004710:Endolymph; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007223:Infant; D029593:Jervell-Lange Nielsen Syndrome / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009154:Mutation; D009759:Nystagmus, Pathologic / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D010641:Phenotype; D004856:Postural Balance; D013548:Sweden; D015837:Vestibular Diseases / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D014722:Vestibule, Labyrinth / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human
keywords: Jervell and Lange-Nielsen Syndrome; KCNQ1 mutations; gross motor developmental delay; phenotype; vestibular dysfunction