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Human gene therapy for RPE65 isomerase deficiency activates the retinoid cycle of vision but with slow rod kinetics
Journal article   Open access   Peer reviewed

Human gene therapy for RPE65 isomerase deficiency activates the retinoid cycle of vision but with slow rod kinetics

Artur V Cideciyan, Tomas S Aleman, Sanford L Boye, Sharon B Schwartz, Shalesh Kaushal, Alejandro J Roman, Ji-Jing Pang, Alexander Sumaroka, Elizabeth A M Windsor, James M Wilson, …
Proceedings of the National Academy of Sciences - PNAS, Vol.105(39), pp.15112-15117
09/30/2008
DOI: 10.1073/pnas.0807027105
PMCID: PMC2567501
PMID: 18809924
url
https://doi.org/10.1073/pnas.0807027105View
Published (Version of record) Open Access

Abstract

The RPE65 gene encodes the isomerase of the retinoid cycle, the enzymatic pathway that underlies mammalian vision. Mutations in RPE65 disrupt the retinoid cycle and cause a congenital human blindness known as Leber congenital amaurosis (LCA). We used adeno-associated virus-2-based RPE65 gene replacement therapy to treat three young adults with RPE65-LCA and measured their vision before and up to 90 days after the intervention. All three patients showed a statistically significant increase in visual sensitivity at 30 days after treatment localized to retinal areas that had received the vector. There were no changes in the effect between 30 and 90 days. Both cone- and rod-photoreceptor-based vision could be demonstrated in treated areas. For cones, there were increases of up to 1.7 log units (i.e., 50 fold); and for rods, there were gains of up to 4.8 log units (i.e., 63,000 fold). To assess what fraction of full vision potential was restored by gene therapy, we related the degree of light sensitivity to the level of remaining photoreceptors within the treatment area. We found that the intervention could overcome nearly all of the loss of light sensitivity resulting from the biochemical blockade. However, this reconstituted retinoid cycle was not completely normal. Resensitization kinetics of the newly treated rods were remarkably slow and required 8 h or more for the attainment of full sensitivity, compared with <1 h in normal eyes. Cone-sensitivity recovery time was rapid. These results demonstrate dramatic, albeit imperfect, recovery of rod- and cone-photoreceptor-based vision after RPE65 gene therapy.
Dependovirus - genetics Genetic Therapy Retinoids - metabolism Blindness - physiopathology Humans Blindness - pathology Retinal Cone Photoreceptor Cells - physiopathology Carrier Proteins - genetics Vision, Ocular - physiology Retinal Cone Photoreceptor Cells - enzymology Retinal Cone Photoreceptor Cells - pathology Retinal Rod Photoreceptor Cells - enzymology Isomerases - genetics Blindness - therapy Eye Proteins - genetics cis-trans-Isomerases Retinal Rod Photoreceptor Cells - pathology Retinal Rod Photoreceptor Cells - physiopathology

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