A gene therapy trial in China tested adeno-associated virus (AAV)-mediated delivery of a functional OTOF gene for autosomal recessive deafness 9 across children and young adults. Ten participants aged 1.5 to 23.9 years showed hearing improvements within one month, sustained at six months, with an average decibel improvement from 106 to 52. The therapy uses the Anc80L65 capsid injected via the cochlea’s round window membrane, marking a significant advance in genetic hearing loss treatment beyond pediatric populations.