First Gene Associated With Most Common Form of Macular Degeneration Identified
09/29/08 Portland, Ore.
Disease is the leading cause of vision impairment in the U.S.
Researchers have identified a gene associated with the dry form of age-related macular degeneration (AMD), the most common form of the disease. Several genes have been associated with the disease, but this is the first to be associated solely with the dry form.
Researchers Michael Klein, M.D. and Peter Francis, M.D., Ph.D. from the Macular Degeneration Center at the Oregon Health & Science University Casey Eye Institute were contributors and co-authors of the research which was recently published in the New England Journal of Medicine online edition.
AMD is the most common form of vision impairment in the developed world, and the leading cause of blindness in people over the age of 65 in the United States. AMD causes damage to the light-sensitive layer at the back of the eye called the retina. The tiny central region of the retina, called the macula, is responsible for central vision. People with AMD develop blurred vision and can eventually lose all central vision, leading to legal blindness.
There are two forms of visually disabling, advanced AMD. Choroidal neovascularization, or “wet” AMD, occurs when blood vessels grow beneath the retina, leading to leakage, bleeding, and scar formation. It often progresses rapidly and is responsible for the majority of severe visual loss from AMD. The advanced “dry” form, also known as geographic atrophy, occurs when deposits form in the macula and lead to cell death. It is also a significant cause of visual loss.
Researchers found a specific variation of the TLR3 gene is significantly associated with protection from the dry form of AMD. The variant appears to protect people from the disease by suppressing the death of retinal epithelial pigment (RPE) cells in the retina. TLR3 is an immune system protein that is helpful in fending-off certain viral infections by detecting a virus and killing the infected cells.
“Currently little treatment is available for the dry form of AMD,” said Francis,co-author of the study and co-director of the MacularDegeneration Center at the OHSU Casey Eye Institute, “but this research opens avenues into identifying treatments for patients afflicted by this form of the disease.”
Oregon Health & Science University is the state’s only health and research university, and Oregon’s only academic health center. OHSU is Portland's largest employer and the fourth largest in Oregon (excluding government), with 12,400 employees. OHSU's size contributes to its ability to provide many services and community support activities not found anywhere else in the state. It serves patients from every corner of the state, and is a conduit for learning for more than 3,400 students and trainees. OHSU is the source of more than 200 community outreach programs that bring health and education services to every county in the state.