There are more than 1500 gene therapy trials going on around the world to treat everything from Parkinson's to blindness to clogged arteries.

Could the key to healing be in the body's building blocks?

Here's a closer look at one gene therapy trial.

Dale turner was barely old enough to read when doctors told him his world would soon go dark.

"The doctors said I would be completely blind by age 10," says Dale.

He has an inherited form of blindness called Leber's congenital amaurosis. A defective gene prevents his retina from producing the nutrients his eyes need.

His vision was like looking down a gun barrel.

He got used to the fact he'd be legally blind for the rest of his life until his parents heard about an experimental therapy -- injecting new, healthy genes into the eye.

"You always have the hope that there will be something for your incurable condition. Growing up, there'll be something for my eyes, someday, that will allow me to see," says Dale.

In a trial, doctors injected hundreds of billions of copies of the working gene beneath the retina in the back of the eye.

Four out of six patients regained vision.

"The improvement in vision corresponded exactly where the genes were replacing the defective gene," says Dr. William Hauswirth, professor of ophthalmic molecular genetics at the University of Florida College of Medicine in Gainesville.

To test the success of the surgery, patients in a British study walked through a maze.

Before treatment, a legally blind man bumped into the wall six times and took almost a minute and a half to get through the course.

After surgery, no bumps and he finished in 14 seconds.

"It's likely it will last for a long time, if not for the life of these patients," says Dr. Hauswirth.

Dale will never forget the first time he went outside after surgery.

"I could see colors like never before, and it was just like a blue sky I've never seen before, and I had this feeling, like what have I been missing out on this whole time?" says Dale.

He's now working on a law degree and hooked on hobbies he thought were impossible.

HIV is one of the latest targets for gene therapy. In a recent trial, scientists found the injection of an anti-HIV gene could make the body resistant to the AIDS virus.

RESEARCH SUMMARY
TOPIC: NEW GENERATION OF HEALING: GENES TO THE RESCUE
REPORT: MB #3057

BACKGROUND: Leber's congenital amourosis (LCA) is a rare, inherited form of blindness that damages light receptors in the retina. The condition usually begins causing blindness in early childhood and leads to total blindness by young adulthood. LCA is most typically passed down through families when both parents have one gene for the disease paired with one normal gene. When that happens, each of their children has a 25 percent chance of inheriting the two LCA genes needed to cause the disorder. Unfortunately, it is currently impossible to determine who is a carrier for LCA until a child is born with the condition, according to the Foundation Fighting Blindness.

GENE THERAPY: For previously irreversible conditions like blindness, medicine is paving the way to cures using the body's own building blocks. In gene therapy, a "normal" gene is inserted into the genome to replace an "abnormal" gene. To deliver the gene, researchers rely on carrier molecules called vectors. So far, the most common vectors are viruses that have been genetically altered to carry normal human DNA (Source: Human Genome Project). Although the introduction of DNA directly into target cells is an option, use has been limited because it only works with certain tissues and requires large amounts of DNA.

The movement of gene therapy into clinical trials has been slow due to the amount of expertise required and the complexity of oversight at the government level, but several trials have showed promise. In an international clinical trial involving the Children's Hospital of Pittsburgh, the University of Pennsylvania, two Italian institutions and several other American institutions, researchers safely restored vision in three young adults with LCA2. Researchers noted it was the first gene therapy trial for a non-lethal condition in children. In an earlier trial, researchers successfully reversed blindness using gene therapy in dogs with the same type of blindness. In the human trial, scientists used a genetically engineered adeno-associated virus to carry a normal version of the gene that is mutated in one form of LCA blindness.

The patients received the injection between fall 2007 and January 2008. Researchers report starting two weeks after the treatment, all three participants reported improved vision in the eye that received the injection. Researchers report the gene therapy for LCA caused no inflammation in the retina or toxic side effects.

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