title: Audiologic presentation of enlargement of the vestibular aqueduct according to the SLC26A4 genotypes.
abstract: OBJECTIVE
  To determine the distribution of the number and types of mutant alleles of SLC26A4 and their correlations with hearing phenotypes in Korean bilateral enlargement of vestibular aqueduct (EVA) patients.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  To determine the number and type of mutant alleles, Sanger sequencing of coding region of SLC26A4 was performed for 56 patients with bilateral EVA who were consecutively recruited. Their correlations with hearing phenotypes were analyzed based on 0.5-, 1-, 2-, and 3-kHz air conduction averages of pure-tone audiometry.
  
  
  RESULTS
  Most patients with bilateral EVA (83.9%) carried two mutant alleles of SLC26A4 (M2), and all others (16.1%) had only one detectable mutant allele of SLC26A4 (M1) in the Korean population. There were no cases with zero mutations. p.H723R/p.H723R was the most frequently observed mutant allelic pair (34%), followed by p.H723R/c.919-2A>G (20%). There was no significant difference in hearing threshold, progression, or fluctuation of hearing level between the M1 and M2 groups. However, focusing on the type of mutations exclusively in the M2 group, cases with p.H723R/c.919-2A>G were associated with more frequent progression of hearing loss during the follow-up period. The cases with p.H723R/c.919-2A>G tended to show slightly better hearing than p.H723R homozygotes, although the difference was not statistically significant. There appears to be a different genotype-auditory phenotype correlation among ethnicities.
  
  
  CONCLUSIONS
  Our data suggest that the auditory phenotype of Korean bilateral EVA patients is more strongly correlated with the type rather than the number of mutations in SLC26A4.
  
  
  METHODS
  NA.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul.
authors.forename: Yoon C
authors.initials: YC
authors.lastname: Rah
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul.
authors.forename: Ah R
authors.initials: AR
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea.
authors.forename: Ja-Won
authors.initials: JW
authors.lastname: Koo
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul.
authors.forename: Jun H
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul.
authors.forename: Seung-Ha
authors.initials: SH
authors.lastname: Oh
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea.
authors.forename: Byung Y
authors.initials: BY
authors.lastname: Choi
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006309:Hearing; D006801:Humans; D007223:Infant; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D009154:Mutation; D010641:Phenotype; D011446:Prospective Studies; D000076988:Sulfate Transporters; D014723:Vestibular Aqueduct; D015837:Vestibular Diseases / Q000235:genetics* / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D026901:Membrane Transport Proteins; C085609:SLC26A4 protein, human; D000076988:Sulfate Transporters
keywords: SLC26A4; enlarged vestibular aqueduct; hearing