However, due to the large gene size, gene replacement therapies may prove challenging in the case of CEP290, although lentiviral transfer of CEP290 has been employed successfully in patient cells27 and administration of multiple AAV intein vectors improves the retinal phenotype of LCA mice by reconstituting full-length CEP290 expression28. The gene discussed is CEP290; the disease is Leber congenital amaurosis.