Congenital deafness due to genetic factors affects 1 to 4 in 1,000 newborns. For certain conditions, gene therapy offers a promising therapeutic approach. The most commonly used vehicle for delivering the correct, or corrective, gene is the recombinant adeno-associated virus (rAAV). However, technical limitations make translation of promising research projects to the clinic difficult. One of those technical limitations is the inability to package large genes into rAAV to deliver them to the relevant cells of the patient. In this project we are developing an improved way to split a gene, which is too large to be packaged in rAAV, into two fragments. These fragments can be individually packaged into a rAAV and, after they are brought into the target cells, lead to the formation of the correct, full-length protein. Our improved approach leads to higher expression of the gene, which significantly increases the chances of hearing recovery in these young patients.