For example, in RPE65 gene augmentation therapy for Leber Congenital Amaurosis improved visual function can be detected in the absence of an ERG improvement both in human patients in phase I/II clinical trials, but also in the dog model when receiving a low dose of therapeutic vector (Bainbridge et al., 2008, 2015; Hauswirth et al., 2008; Maguire et al., 2008). This evidence concerns the gene RPE65 and Leber congenital amaurosis.