Two studies regarding the effects of gene therapy on the retina have been published. This is a first step in curing a congenital retinal disease, called Leber’s congenital amaurosis (LCA), a remarkable success in the fields of Genetics and Ophthalmology.
LCA is a inherited disease of the retina, that affects 1 in 80,000 people. The disease has an early onset, appearing at birth or in the first few months of life and its main symptom is, as the name describes, amaurosis. This means the loss of sight that is not associated with a lesion.
The studies were conducted at the University College London’s Institute of Ophthalmology and at the University of Pennsylvania’s Scheie Eye Institute in the US. The principle of the study was injecting healthy genes in the affected retinal area of LCA patients.
Previous gene therapy programmes have been conducted in regards to LCA, using an adeno-associated virus on the RPE65 gene, the mutated gene that causes LCA. While this course of treatment has shown promising results, it still has not reached the point where it may be widely used.
These two studies focusing on injecting healthy genes in the retina have proven to be successful to a certain extent, but as the method is at the moment, it only has a temporary effect on the patients’ sight. An effect has been observed in the night vision of the twelve patients in the study. The improvement observed peeked at six to twelve months post-treatment and then started to decline up to the point where it disappeared completely.
“Within days of the injections, some patients reported increases in their ability to see dim lights they had never seen before. It was remarkable for us to get this feedback that things were indeed changing positively,” said Dr. Jacobson, M.D., Ph.D., who conducted the clinical trial at the University of Pennsylvania’s Scheie Eye Institute.
The studies provided six years of data on the effects of gene therapy on LCA. Aside from the rapid effect on the greater light sensitivity, some patients showed a longer term improvement as well. They managed to make use of the area near the injection site for seeing letters, function for which the fovea is normally responsible. The fovea is a component of the eye that has a high density of photoreceptors and therefore provides detailed sight.
This ground-breaking study will be the base line of future research on the matter, as gene therapy has shown tremendous results. “As with any application of a novel therapy, it now needs to be fine-tuned.”, said Dr. Paul A. Sieving, M.D., Ph.D., director of the National Eye Institute.
While not having cured LCA completely, this newest version of gene therapy is the first step in curing a congenital retinal disease. Researchers are looking for a more potent gene-therapy treatment plan, based on the results of these two studies, in the hope that soon enough diseases like LCA will be history.
Image Source: eyeworld.org