Genetic landscapes and audiological trajectories in pediatric asymmetric hearing loss and interaural asymmetry.

Abstract

Objectives.: To delineate the genetic landscapes and audiological trajectories of pediatric asymmetric hearing loss (AHL) and interaural asymmetry (IA) using a systematic multi-tiered genetic testing strategy extending to whole-genome sequencing (WGS), and to assess the clinical implications for individualized auditory rehabilitation.

Methods.: The study was a retrospective cohort study of pediatric patients (≤18 years) with sensorineural hearing loss (SNHL) who underwent comprehensive genetic testing at a tertiary cochlear implantation (CI) center between March 2021 and February 2025. AHL was defined as better-ear pure-tone audiometry (PTA) of 30-60 dB HL, and worse-ear PTA >70 dB HL on two consecutive baseline audiograms. IA was defined as an interaural difference of >15 dB, and subclassified as mild (15-30 dB) or severe (>30 dB). Longitudinal changes in better-ear thresholds and progression to CI were evaluated.

Results.: Of 551 pediatric patients with SNHL, 486 pediatric patients met the above inclusion criteria. AHL was present in 29/486 (6.0%), and mild and severe IA were observed in 45/486 (9.3%) and 40/486 (8.2%), respectively. Genetic diagnostic yield did not differ between AHL and symmetric SNHL (55.1% vs 62.1%, p=0.462), whereas it decreased with increasing IA (0-15 dB: 64.3%; 15-30 dB: 60.0%; >30 dB: 37.5%; p=0.004), The genetic landscape of AHL/IA was heterogeneous but converged on two recurrent deafness genes (SLC26A4 and GJB2), with SLC26A4 variants the most frequent. Genetically diagnosed patients exhibited progressive deterioration in better-ear thresholds across most frequencies, whereas genetically undiagnosed patients showed minimal change. Specifically, SLC26A4-related DFNB4 patients had the highest progression to CI in the better ear.

Conclusion.: Genetically diagnosed cases show progressive better-ear deterioration. This is particularly evident in SLC26A4-related DFNB4, which has a higher rate of progression to CI than other AHL/IA-associated genes. These findings support etiology-based prognostication and individualized rehabilitation planning.