PCDH15 and deafness: Since then, significant progress has been made in gene therapy for hereditary deafness caused by mutations of genes such as including Otof, Tmc1, and Pcdh15, and some treatments have restored the hearing of mouse models to wild‐type levels.[5, 6, 7, 8, 9, 10, 11, 12, 13] Notably, in clinical trials of gene therapy for treating autosomal recessive deafness 9 (DFNB9), the patients' hearing was recovered without evident adverse reactions.[14, 15, 16] Nevertheless, numerous challenges persist in using gene therapy for treating deafness due to the intricate structure of the cochlea.