Multiple laboratories have effectively used this split vector approach in preclinical models: first for the delivery of the erythropoietin genomic locus [115], but later for retinal disease genes caused by variants in the MYO7A gene (Usher syndrome, type 1B) [116,117] and the ABCA4 gene (Stargardt disease) [117]. The gene discussed is EPO; the disease is Stargardt disease.