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Wednesday, January 28, 2009
At the end of the tunnel
By Olivier Uyttebrouck
Journal Staff Writer
Alisha Bacoccini didn't expect a miracle cure for a lifetime of progressive blindness when she volunteered for an experimental study last year.
But she believes her contribution one day will lead to new genetic therapies that could prevent blindness or restore sight for thousands, including herself.
"I don't have any doubt that there will be a cure for genetic diseases," Bacoccini, 21, said recently. "There will be a cure sometime."
Bacoccini's world has been one of encroaching darkness since she was diagnosed at 11 months with retinitis pigmentosa, a disease caused by a defective gene that damages her retinal cells. Bacoccini sees the world in shades of light and dark. She can read and write text messages if the screen is brightly lit.
Genetic testing identified the Albuquerque woman as a good candidate for an experimental treatment shown to improve sight in dogs with the same defective gene.
In May, researchers at the University of Pennsylvania injected 15 million healthy copies of the gene into Bacoccini's right eye, her weakest. She was only the fifth person enrolled in the study, said Dr. Jean Bennett, a molecular geneticist leading the study.
"I really think Alisha and the other individuals involved in this are incredible pioneers," Bennett said in an interview. "They knew that they might not benefit. In fact, they could suffer worse vision from participating in the study."
Retinitis pigmentosa is a catch-all term for a family of genetic disorders, Bennett said. Tests specified Bacoccini's illness as Leber's congenital amaurosis, caused by a defective gene called RPE65.
Researchers package the healthy RPE65 genes in a harmless virus that acts as a genetic delivery system, inserting the good genes into Bacoccini's retinal cells. Bacoccini's illness affects some 3,000 people in the United States.
"Even though it's rare, the general approach is one that could potentially be used for many inherited eye diseases," Bennett said. They include common disorders such as age-related macular degeneration, diabetic retinopathy and others, she said.
In Bacoccini's case, her right eye sees more light now than before the procedure.
"It's still blurry but there's a lot more light that's being processed to my brain," she said.
The additional light hasn't improved the sight in her right eye, she said, possibly because she can't interpret the images.
"It's sort of like my brain has more information but doesn't know what to do with it," she said. And bright sunlight can give her headaches.
Bacoccini was among three patients in the second phase of the study. Another patient in her group, a 9-year-old boy, showed more improvement and can now read a blackboard. Bennett said younger children may respond better because their brains can more easily learn to perceive images. Strangely, Bacoccini has experienced some visual improvement in her left eye, the stronger one, which was untouched by the procedure. There is a marked decrease in nystagmus, an involuntary jerking movement, improving her left eye's ability to focus.
"It's totally worth every bit of it," Bacoccini said of her five trips to Philadelphia. The improvements, though limited, give Bacoccini hope that future advances will help restore her sight. "That I have no doubt in."
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