Data availability Participant data are de-identified and available in the text, figures and tables. The statistical analysis plan is included in the clinical trial protocol, which is available in  Supplementary Information . Requests for more information should be communicated to the corresponding author Y.S.  Source data are provided with this paper. Code availability This work does not include any new code or software. References Yasunaga, S. et al. A mutation in OTOF , encoding otoferlin, a FER-1-like protein, causes DFNB9, a nonsyndromic form of deafness. Nat. Genet. 21 , 363–369 (1999). Article   CAS   PubMed   Google Scholar   Lv, J. et al. AAV1-hOTOF gene therapy for autosomal recessive deafness 9: a single-arm trial. Lancet 403 , 2317–2325 (2024). Article   CAS   PubMed   Google Scholar   Wang, H. et al. Bilateral gene therapy in children with autosomal recessive deafness 9: single-arm trial results. Nat. Med. 30 , 1898–1904 (2024).…