The opportunities and challenges of gene therapy for treatment of inherited forms of vision and hearing loss.

Inherited forms of blindness and deafness are highly prevalent and severe conditions which significantly impact the lives of millions of people worldwide. The lack of therapeutic options for these conditions poses a major socioeconomic burden. Over the last decades, gene therapy has proven to be a life changing treatment for hereditary and acquired forms of diseases and extensive preclinical investigation in animal models of both retinal and inner ear disorders has highlighted promising translational opportunities for these disorders, too. This led to dozens of clinical trials investigating the efficiency of gene therapy-based approaches, with some of the products for retinal conditions successfully reaching Phase III of development or even market authorisation. However, challenges remain for the use of gene therapy, which are related to both the features of the delivery vehicles currently available, and characteristics of the retinal and inner ear disorders targeted. Therefore, further developments in gene therapy platforms' design, including exploitation of novel technologies such as genome editing, RNA-targeted therapies, and optogenetics, are actively ongoing, driving the field forward. Here, we will review the ongoing applications and achievements of gene therapy for treatment of inherited forms of blindness and deafness as well as the developments that are being pursued in the field to overcome the current limitations.