MONDAY, Oct. 26 (HealthDay News) -- Gene therapy for a rare inherited sight disorder in which severely impaired vision in childhood usually results in blindness in adulthood can substantially improve vision, particularly in children, according to a study published online Oct. 24 in The Lancet.

As part of a Phase I trial, Albert M. Maguire, M.D., from the University of Pennsylvania in Philadelphia, and colleagues treated 12 patients with incurable inherited retinal degeneration due to Leber's congenital amaurosis with a single subretinal injection in the worst eye of a virus carrying the RPE65 gene, which is mutated in the disease and encodes a protein needed for the isomerohydrolase activity of the retinal pigment epithelium. The disease has been traced to mutations in any of 13 genes, and this particular mutation accounts for about 6 percent of cases, they note.

The researchers found that the virus was well tolerated and led to sustained improvements in five subjective and objective measures of vision. Patients also showed an increase of at least 100-fold in pupillary light responses. Children (aged 8 to 11 years) improved the most, with all gaining ambulatory vision allowing them to walk unaided even in dim light.

The study "will further boost gene therapy trials and provide hope for patients with inherited blindness and other genetic disorders," write the authors of an accompanying editorial. "As novel therapeutic strategies are being developed for each of the separate genetic defects, ascertaining and genotyping the corresponding patients will be the real challenge in the coming decade."

Several authors reported financial and consulting relationships with drug companies, although this often did not involve retinal research. Two authors are co-inventors of a pending patent for a method to treat or slow the development of blindness, but have waived any financial interest in the technology.

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