Core Viewpoint - A recent study by Southeast University, Beijing Institute of Technology, and Wuhan University demonstrates that precise and efficient DNA base editing can restore normal hearing in adult DFNB9 mouse models [4][12]. Group 1: Research Findings - The study focuses on the OTOF gene mutation, which causes autosomal recessive non-syndromic hearing loss (DFNB9), primarily affecting the auditory nerve's ability to transmit signals to the brain [6]. - The research team identified the best adenine base editor for repairing the pathogenic Otof c.2815C>T (p.Gln939*) mutation, with Nme2ABE8e showing superior editing efficiency [7][11]. - Treatment using AAV-mediated delivery of Nme2ABE8e to one-month-old adult Otof-deficient mice restored hearing function to near-normal levels, with effects lasting at least six months [8][11]. Group 2: Treatment Window and Safety - Successful treatment in four-month-old mice indicates a relatively wide therapeutic time window for DFNB9, suggesting that intervention can occur beyond the critical period of auditory system development [8][11]. - Safety assessments revealed no ototoxicity or neurological deficits, confirming the safety of the adenine base editing approach [11][12]. Group 3: Clinical Implications - The findings highlight the potential for gene therapy in DFNB9 patients, indicating that even adults can benefit from such treatments, as evidenced by a clinical trial where a 23.9-year-old patient showed encouraging auditory recovery [12].