Inflammation and Oxidative-Stress Pathways Are Associated with Idiopathic Sudden Hearing Loss: A Genome-Wide Association Study in 15,494 Japanese Individuals

The etiology of idiopathic sudden sensorineural hearing loss (iSSNHL) remains unclear, and genome-wide genetic evidence is limited. We conducted a multicenter Japanese case–control genome-wide association study including 192 clinically defined iSSNHL cases and 15,302 controls aged ≥80 years without a history of hearing loss. After cross-platform SNP harmonization and imputation (Eagle/Minimac4), association testing was performed using dosage-based logistic regression in PLINK 2.0, adjusting for sex and principal components (PC1–PC10). Gene- and pathway-level analyses were conducted using MAGMA and the PANTHER overrepresentation test. Genomic inflation was modest (λ_GC = 1.04). Eight loci reached genome-wide significance (p < 5 × 10−8), led by FHIT, with additional loci near LHX2, TRMT1L, MEGF10, SPATS1, SAMD5, MYT1L, and ID4; 21 loci met the suggestive threshold (p < 1 × 10−6). MAGMA identified eight genes at FDR < 0.05 (FHIT, TRMT1L, MEGF10, RNF2, SWT1, VAMP1, TAPBPL, and C9orf3). These findings suggest that immune-inflammatory and cellular stress–homeostasis mechanisms may contribute to iSSNHL susceptibility and provide candidate loci for future replication and functional studies.