Vision Improvement 1 Year after Gene Therapy in Leber’s Amaurosis
August 20, 2009
One year after three young adults with Leber’s Congenital Amaurosis (LCA) were treated with gene therapy, researchers announced that the patients are still experiencing the same level of visual improvement that was originally noted a few weeks after treatment. This is the first report that documents safety and efficacy results in treating 3 adults with LCA 1 year after gene therapy. These results were reported in Human Gene Therapy, now online, and in a letter in the New England Journal of Medicine (NEJM) this week.
The three patients have a specific type of LCA caused by a genetic mutation in the RPE65 gene. This gene normally makes a critical protein in the visual cycle. Without this RPE65 protein, light-sensitive photoreceptor cells are starved of a retina-specific form of vitamin A and cannot function.
To correct this genetic defect, the researchers targeted retinal regions which contained impaired, but intact, photoreceptors and injected healthy copies of the RPE65 gene under the retina. One year after the single injection, the healthy genes continue to make this critical protein, increasing the retina’s sensitivity to light.
One of the patients reported that she was able to read an illuminated clock for the first time; this was not due to any increase in light sensitivity (which has not changed since the first month of the study). An examination of this patient found that the patient’s fixation of gaze shifted to the region of the treated retina.
As more results of ocular gene therapy in hereditary blindness emerge, the details of treatment can be further determined.
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