Exploring Embryonic and Postnatal Gene Therapy Approaches for GJB2-Related Deafness: A Scoping Review

Purpose: Hearing loss (HL) is a prevalent condition significantly impairing quality of life, with genetic mutations accounting for a substantial proportion of congenital cases, notably those involving the GJB2 gene encoding connexin 26. This study aims to analyze the current knowledge, feasibility, and challenges of gene therapy targeting GJB2-related HL, emphasizing both embryonic and postnatal interventions. Methods: A comprehensive scoping review was conducted across electronic databases up to October 2025, including studies focusing on GJB2-associated HL, gene therapy approaches, and the timing of interventions. Data extraction encompassed mutation types, animal models, delivery strategies, outcomes, and ethical considerations. Results: The results indicated over 467 GJB2 variants which could impair cochlear ion homeostasis and development. Animal models, mainly murine, demonstrated early-onset degeneration with limited recovery following delayed gene therapy, while early postnatal intervention showed greater efficacy. Viral vectors like AAV have been employed for targeted gene delivery via cochlear injections, achieving partial restoration of connexin expression and cochlear function, yet they have faced limitations including transduction efficiency, immune responses, and long-term stability. Challenges in translating these findings to humans have been compounded by anatomical, immunological, ethical, and safety issues, particularly regarding embryonic gene therapy and germline modifications. Ethical frameworks can vary internationally, highlighting the necessity for careful regulation. Conclusions: While promising advances in gene therapy for GJB2-related HL have been achieved in preclinical studies, significant scientific, technical, and ethical barriers must be addressed before clinical application, especially during embryogenesis. A multidisciplinary, cautious approach is essential to realize the potential of gene therapy in restoring natural hearing while safeguarding individual and societal interests.