Washington, Apr 28: Researchers from University of Pennsylvania have successfully restored vision among patients with a rare form of congenital blindness using gene therapy. Leber congenital amaurosis (LCA) is a group of inherited blinding diseases that damages light receptors in the retina. It usually begins stealing sight in early childhood and causes total blindness during a patient's twenties or thirties.
"This is the first gene therapy trial for a non-lethal pediatric condition," said Dr Albert M. Maguire, Associate Professor, Department of Ophthalmology, University of Pennsylvania School of Medicine and a physician at The Children's Hospital of Philadelphia. "Patients' vision improved from detecting hand movements to reading lines on an eye chart," he added
The study was conducted over three patients, aged 19, 26 and 26. Scientists used a vector, a genetically engineered adeno-associated virus, to carry a normal version of the gene, called RPE65 that is mutated in one form of LCA. The patients were given the gene therapy via a surgical procedure performed by Maguire between October 2007 and January 2008 at The Children's Hospital of Philadelphia.
The findings revealed that in the first two weeks after injections all three patients reported improved vision in the injected eye. "Standard vision tests showed significantly improved vision in the patients," said Dr Alberto Auricchio, a study leader from the Telethon Institute of Genetics and Medicine and University of Naples Federico II. Moreover, each injected eye became nearly three times more sensitive to light, and each was improved compared to the uninjected, previously better functioning eye.
Although the patients have not achieved normal eyesight researchers feel that the results would open up new avenues for further studies.
"The current clinical trial will continue with more patients and with ongoing follow-up to monitor results," said Bennett. "We expect improvements to be more pronounced if treatment occurs in childhood, before the disease progresses," said Dr Jean Bennett, Professor of Ophthalmology at Penn and Senior Investigator at the F.M. Kirby Centre for Molecular Ophthalmology at Penn's Scheie Eye Institute.
The international team led by The University of Pennsylvania, includes The Children's Hospital of Philadelphia, the Second University of Naples and the Telethon Institute of Genetics and Medicine (both in Italy), and several other American institutions
The findings appear in an online article in the New England Journal of Medicine.