Gene therapy saves from blindness

Gene therapy restores vision
Dmitry Safin, Compulenta

The first phase of clinical trials of a genetic therapeutic technique for restoring vision in patients who suffer from a rare hereditary retinal disease (Leber's amaurosis) has been successful.

Vision in patients with Leber's amaurosis worsens gradually, and complete blindness develops by the age of forty. One of the subtypes of this disease, LCA2, is associated with defects in the RPE65 gene, which is responsible for the production of the main visual pigment rhodopsin by photosensitive retinal cells.

In 2001, experts from the University of Pennsylvania (USA) proved that in dogs with a defective RPE65 gene, vision can be partially restored by injecting a "copy" of this gene. Two years ago, researchers conducted the first human trials and received encouraging results.

Recently, scientists and their colleagues from Belgium and Italy completed the first large-scale testing of the technique on twelve volunteers, including four children aged eight to eleven years. Injections of an adeno-associated virus were used to deliver the gene.

Gene therapy has proved particularly effective in the treatment of children who, unlike adult patients, still have a significant amount of intact retinal tissue. So, in adult patients, the sensitivity of the eyes to light increased "only" by an order of magnitude, and in children – by 3-4 orders of magnitude. One of the patients, nine-year-old Corey Haas, told reporters that the treatment gave him the opportunity to play baseball, read books with large print and ride a bike on his own.

Corey Haas, his parents and scientists from the University of Pennsylvania (photo by Daniel Burke).

The researchers' report is published in the journal The Lancet.

Prepared based on ScienceNOW materials.

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26.10.2009