Gene therapy improves the vision of people with a genetic form of blindness, but does not stop the loss of the light-sensitive photoreceptor cells in the retina.

Childhood blindness as a result of Leber congenital amaurosis (LCA) occurs as a result of photoreceptor dysfunction and degeneration, owing to a mutation in the gene RPE65. In addition to fixing the dysfunction, researchers hoped therapy with a working copy of the gene would slow the loss of the cells. But, Artur Cideciyan at the University of Pennsylvania in Philadelphia and his group found that the loss continues. In dogs bearing the LCA mutation, those that were treated at a disease stage approximating to that in humans also showed photoreceptor deterioration.

The results suggest that treatment for this hereditary blindness also needs to address long-term protection of the light-sensing cells.

Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1218933110 (2013)