Gene therapy has been used to restore sight in people with Leber congenital amaurosis (LCA), a rare inherited eye disease that causes severe vision loss or blindness.
Artur Cideciyan and colleagues used a virus to deliver the RPE65 gene to the retinas of three young adults affected by the condition. Results showed a statistically significant increase in visual sensitivity just 30 days after treatment. Dramatic improvements in rod and cone cell function were observed and tests showed that the gene therapy restored nearly all of the loss of light sensitivity caused by LCA. However, the treated rod cells were slow to adapt to low light levels – requiring 8 h or more to reach full sensitivity, compared with less than 1 hour in healthy eyes.
The authors conclude: “These results demonstrate dramatic, albeit imperfect, recovery of rod- and cone-photoreceptor-based vision after RPE65 gene therapy.”
It is thought that the gene therapy could be ready to treat specific inherited diseases of the retina within just two years, and will be ready for testing on people with age-related macular degeneration within three years.
Cideciyan A, Aleman TS, Boye SL, Schwartz SB, Kausal S, Roman AJ, et al. Human gene therapy for RPE65 isomerase deficiency activates the retinoid cycle of vision but with slow rod kinetics. PNAS Published September 22, 2008. doi:10.1073/pnas.0807027105
