USH2A and Usher syndrome: Whilst suitable for a number of ciliopathy-related genes, such as RPGR (3.5 kb), many genes are beyond this capacity, including CEP290 (7.4 kb) and several of the Usher-syndrome-associated genes (MYO7A: 6.6 kb, CDH23: 10 kb, ADGRV1: 18.9 kb, USH2A: 15.6 kb).