Bialellic mutations in SLC26A4 Are Associated With Additional Inner Ear Abnormalities

Abstract

Objectives/Hypothesis: To identify and characterize potential correlations between the SLC26A4 (PDS) genotype and longitudinal hearing loss in a cohort of patients with enlarged vestibular aqueduct (EVA) with or without additional inner ear anomalies. Study Design:Retrospective chart review at a tertiary care children's hospital.Methods: 53 individuals, aged 2 to 30 years with EVA in at least one ear were studied (84 affected ears). All subjects underwent genetic testing for SLC26A4. Statistical correlation between hearing loss, as measured by four-frequency pure tone average (500, 1000, 2000, and 4000 Hz), number of mutant SLC26A4 alleles and presence of inner ear anomalies detected by computed tomography or magnetic resonance imaging was undertaken. The median follow-up time was 18 months with a standard deviation of 14 months.Results: There were 18 males (34%) and 35 females (66%). 5 subjects (9.4%) had two pathogenic SLC26A4 mutations, 8 (15.1%) had one pathogenic mutation, and 40 had no mutations (75.5%). GEE model showed that biallelic SLC26A4 mutations were significantly correlated with a higher number of additional inner ear abnormalities (mean=3.1) compared to patients with one (mean=1.5) or no mutations (mean=1.63) (P=0.01). There was no correlation between the number of mutations and progression of hearing loss (P=0.28). Fluctuating hearing loss was not correlated with the presence of additional inner ear abnormalities (P=0.80) or the number of mutant alleles of SLC26A4 (P=0.43). Conclusions:The number of mutant alleles of SLC26A4 is significantly associated with the presence of additional inner ear anomalies but not with changes in hearing.