Genetic Basis of Hearing Loss in Mongolian Patients: A Next-Generation Sequencing Study

Background/Objective: The genetic landscape of sensorineural hearing impairment (SNHI) varies across populations. In Mongolia, previous studies have shown a lower prevalence of GJB2 mutations and a higher frequency of variants in other deafness-related genes. This study aimed to investigate the genetic variants associated with idiopathic SNHI in Mongolian patients. Methods: We utilized the next-generation sequencing for investigating the causative mutations in 99 Mongolian patients with SNHI. Results: We identified pathogenic variants in 53 of the 99 SNHI patients (54%), with SLC26A4 being the most frequently mutated gene. The c.919-2A>G variant in SLC26A4 was the most prevalent, accounting for 46.2% of the mutant alleles. In addition, we identified 19 other known and 21 novel mutations in a total of 21 SNHI genes in autosomal recessive or dominant inheritance patterns. Conclusions: Our findings expand the understanding of the genetic landscape of SNHI in Mongolia and highlight the importance of considering population-specific variations in genetic testing and counseling for SNHI.