Worldwide, there are more than 7,000 rare diseases for which 80 % are of genetic origin and for which the gene or genes are not yet all known. Although the interest in rare diseases has increased in recent years, there is a lack of therapeutic strategies for most of them. During my thesis, I focused on the identification and validation of new genes associated with neurosensory and neurodevelopmental diseases. The strategy I used during my thesis to identify new disease-causing genes is based primarily on the analysis of high-throughput sequencing data from patients, the confirmation of variants by Sanger sequencing, and the performance of functional experiments using patient cells and the zebrafish model to proof the pathogenicity of the novel gene mutations. Overall, I contributed to the identification of three novel disease genes associated with neurodevelopmental and neurosensory diseases. The results obtained in this thesis improve the understanding of the pathophysiology of these diseases and may help to find new therapeutic targets.