CEP290 and Leber congenital amaurosis: Another limitation is the length of the cDNA that the AAV can package for delivery [27–30], which prevents replacement of very large genes, such as ATP-binding cassette subfamily a member 4 (ABCA4, ∼7.3 Kb), which causes Stargardt disease [31, 32] and centrosomal protein of 290 kDa (CEP290, ∼7.9 kb) which causes another form of LCA [33].