The influence of mutations in the SLC26A4 gene on the temporal bone in a population with enlarged vestibular aqueduct

Abstract

Objective: To correlate genetic and audiometric findings with a detailed radiologic analysis of the temporal bone in patients with enlarged vestibular aqueduct (EVA) to ascertain the contribution of SLC26A4 gene mutations to this phenotype. Design: A retrospective review of patients with EVA identified in a database of pediatric hearing-impaired patients. Setting: A tertiary care pediatric referral center. Patients: Seventy-one children with EVA and screening results for SLC26A4 mutations. Main Outcome Measures: Genetic screening results, audiometric thresholds, and radiographic temporal bone measurements. Results: Seventy-one children with EVA were screened for SLC26A4 mutations. Mutations were found in 27% of children overall, while only 8% had biallelic mutations. The mean initial pure-tone average (PTA) was 59 dB; the mean final PTA was 67 dB. A bilateral EVA was found in 48 (67%) of the children; a unilateral EVA was found in 23 (33%). Progressive hearing loss (in at least 1 ear) was seen in 29 (41%) of the patients. The strongest genotype-phenotype interaction was seen in children with a bilateral EVA. Among children with SLC26A4 mutations, there was a significantly wider vestibular aqueduct at the midpoint and a wider vestibule width (P