A Natural History Study in Pediatric Participants With Hearing Loss Due to OTOF, GJB2, or GJB2/GJB6 Mutations

Inclusion Criteria:

• Participant is no older than 7 years (inclusive) at the time of the parent/legalguardian signing the informed consent form (ICF)

• Participant has 1 of the following genotypes and meets the associated audiologiccriteria based on physiologic and/or behavioral measures of inner ear function:

• Biallelic pathogenic or likely pathogenic OTOF mutations with severe to profoundsensorineural hearing loss (SNHL; ≥ 85 dB HL) and confirmed presence of OAEs

• Biallelic pathogenic and truncating GJB2 mutation(s) with moderate ormoderately-severe SNHL (≤41 to <71 dB HL)

• Digenic pathogenic or likely pathogenic mutations in GJB2 and GJB6 genes with mildor worse SNHL (>26 dB HL)

• Participant has at least 1 ear that has not received a cochlear implant (CI)

Exclusion Criteria:

• History of or active participation in an interventional trial related to hearingloss

• History or presence of any other permanent/untreatable hearing loss conditions,including genetic conditions other than those involving biallelic OTOF or GJB2mutations, or digenic GJB2/GJB6 mutations

• History of treatment with ototoxic drugs