Conclusion: In children with enlarged vestibular aqueduct syndrome (EVAS), their hearing was more related to genotype than VA size, and VA size was related to genotype.
Objective: To study genotypes of the SLC26A4 gene, types and levels of hearing loss, and vestibular aqueduct (VA) size in children with EVAS.
Methods: A total of 271 children with nonsyndromic sensorineural hearing loss and EVA underwent SLC26A4 gene screening. According to genotype typing, the phenotypes including pure tone average (PTA), distribution of subjects, and diameters of the external aperture and middle portion of the VA, were compared by t test or Pearson's χ(2) tests. Further, divided by the dilated level of the VA, subject distribution in different hearing loss levels was compared by Pearson's χ(2) test.
Results: In all, 66 types of mutations were identified and 2 were novel (c.665G >T and c.1639G >A). Biallelic genotype was found in 207 subjects, monoallelic in 56, and no mutation in 8. The hearing loss was more stable in the subjects with monoallelic mutation than in other genotype groups. An air-bone gap was more frequently found in subjects with biallelic missense mutations than in other groups. The patients with no mutation had the most slightly enlarged VA. There was no dominant correlation between hearing loss level and VA size, and between VA size and different genotypes.