Summary Mutations in USH2A (usherin) are common causes of autosomal recessive blinding diseases in non-syndromic retinitis pigmentosa as well as syndromic Usher syndrome type II that manifests congenital hearing loss as well. There is no effective therapy for these diseases. How usherin contributes to photoreceptor health is poorly understood. An usherin-deficient animal model that exhibits severe retinal degeneration as in human patients is essential for understanding the pathological mechanisms and for development of effective therapies to preserve or restore vision. This project is aimed at generating an usherin-deficient model that recapitulates the phenotypes found in human patients.