RPE65 and Abnormal retinal morphology: Supplemental gene therapy is successfully applied in other inherited retinal diseases due to, for example, mutations in RPE65. 8 The US Food and Drug Administration and the European Medicines Agency recently approved the first gene therapy drug for inherited retinal diseases caused by variants in RPE65. 9 The primary targets for RPE65 gene therapy are cells of the retinal pigment epithelium.