The variant NM_004086.3:c.259G>T in COCH is a missense variant predicted to cause substitution of Glycine to Tryptophan at amino acid 87 (p.Gly87Trp). The highest population minor allele frequency in gnomAD v4.1.1 is 0.00008474% (1/1180026 -European [non-Finnish], PM2_Supporting met). The in silico predictor REVEL yields a score of 0.911, which is above the threshold of 0.7 (PP3 met). This variant was identified in a Dutch family (PMID:16835921), in which it segregated with progressive, late-onset HL and concomitant vestibular dysfunction in 16 affected family members (PP1_Strong met). Given the highly specific phenotype of progressive hearing loss with vestibular dysfunction, the HL-VCEP decided to apply PP4 evidence criteria. Functional studies showed no alteration in protein secretion or aggregate formation; however, protein cleavage was not evaluated. Therefore, BS3_Supporting was not applied. In summary, based on the current evidence (PP1_Strong, PP4, PP3 & PM2_Supporting), the variant NM_004086.3(COCH):c.259G>T (p.Gly87Trp) is classified as Likely-Pathogenic for autosomal dominant non-syndromic SNHL based on the ACMG/AMP criteria applied, as specified by the ClinGen HL-VCEP (ClinGen Hearing Loss VCEP specifications version 2; 09/16/2026).