(February 8, 2012 - Insidermedicine)

Gene therapy is helping those suffering from a hereditary congenital eye disease regain their vision. The research is published in Science Translational Medicine.

Here is some information about Leber congenital amaurosis, or LCA:

•    It is an eye disorder present from birth in which a genetic mutation impairs the production of an enzyme critical for proper vision

•    Individuals with LCA are often born with poor vision, and it can worsen over time

•    It is one of the most common causes of blindness in childhood, affecting 2 to 3 per 100,000 newborns

Researchers from The Children's Hospital of Philadelphia and the University of Pennsylvania injected the eyes of 3 adults suffering from LCA with a virus carrying a normal version of the very gene that was causing their vision loss. All of these patients had received the same treatment in 2009 in one eye, with good success. This time, their previously untreated eye was given the injection.

The investigators were concerned that a second injection could cause a vaccine-like reaction of the immune system, which might not only prevent the second treatment from working but also diminish the effects of the first treatment. Fortunately, no such reaction was noted. Instead, vision improved once again. Two of the three patients were able to navigate an obstacle course in dim light. Brain imaging revealed that the vision center of their brain was more intensely activated by visual stimuli such as flickering checkerboard pattern than it had been before treatment. Also, patients’ pupils responded more sensitively to changes in light intensity.

Today’s research offers a proof of principle that retinal disorders such as LCA can be treated with gene therapy. Longer, more detailed studies will determine if this therapy could have more widespread use.