Scientists from the Institut Pasteur, Inserm, CNRS, and many other universities have collaborated to restore hearing in adult mice of DFNB9 deafness. Someone who has DFNB9 deafness are deficient in the gene coding for otoferlin, which is a protein that transmits sound information. The scientists restored the auditory synapase threshold, which receives the sound information, to a near-normal level. DFNB9 deafness is the same for humans and mice, that is why mice are used as models to test the efficiency of gene therapy. Scientists came up with a Adeno-associated virus (AAV) approach, known as the dual AAV strategy becuase it uses two different recombinant vecotrs. An intracochlear injection of the vector pair was injected in adult mice to reconstruct the otoferlin coding region, resulting to a long-term restoration of otoferlin. With these findings, scientists can help individuals with DFNB9 deafness, to restore their hearing and also discover other types of deafness and hopefully be able to cure the other types of deafness.