October 23, 2006 — Researchers at the John A. Moran Eye Center at the University of Utah have identified a gene called HTRA1 that contributes to a major risk of Age Related Macular Degeneration (AMD), the most common cause of irreversible vision loss in the developed world. The discovery of this gene allows anyone to take a simple blood test to find out if they are up to 700% more likely to develop AMD than the average person. This is particularly important for individuals who have a family history of blinding eye conditions.
This test, which is strongly predictive of AMD, will allow people with high risk for AMD to adapt diet and lifestyle changes to lower their risk or delay the onset of the disease. Perhaps more significantly, because this research has identified an entire new pathway and drug target for AMD, this discovery will very likely lead to new and effective treatments for the disease.
Lead by Kang Zhang M.D., Ph.D., Director of the Division of Ophthalmic Genetics at the Moran Eye Center and Associate Professor of Ophthalmology and Visual Sciences at the University of Utah, the study will be published online October 19 in the journal Science. Dr. Zhang explains the significance of the discovery: “Several previous studies have implicated a major gene at chromosome 10q26 that affects the risk of AMD, but until this study the precise gene has not been identified.”
AMD is a degenerative disorder affecting a portion of the retina called the macula. The macula is responsible for clear, central vision.
Individuals with AMD have difficulty with activities like reading, watching television, and seeing faces of people directly across the table. The disease often leads to legal blindness in patients older than 60 years of age.
How did the researchers discover that this gene is involved in AMD? In this study the researchers genotyped 581 people with AMD and 309 without AMD in a Utah population. Their studies demonstrate that if a person has a mutant copy of the HTRA1 gene, they have a significantly increased risk of developing age related macular degeneration during their lifetime.
“If anyone in your family has a history of macular degeneration, this test would be advised,” says Dr. Zhang. “The addition of this new piece to the AMD puzzle suggests that this gene plays a critical role in the formation of tiny protein and fat-containing debris called soft confluent drusen, a precursor of AMD, and promotes abnormal growth of blood vessels typical of the wet form of AMD. The gene is also a critical genetic clue that will allow us to move forward with developing treatments and preventive strategies for patients with AMD. With our massive population swing toward the at-risk age (60+) for AMD, finding treatments and cures is vital.”
In addition to Dr. Zhang’s team at the Moran Eye Center, other investigators contributing to the new findings are from the Program in Human Molecular Biology and Genetics at the Eccles Institute of Human Genetics, the Division of Genetic Epidemiology, and the Department of Biomedical Informatics at the University of Utah; the Sichuan Academy of Medical Sciences & Sichuan Provincial People’s Hospital, China; the Jules Stein Eye Institute at the University of California at Los Angeles; and Yale University.
Funding for the study was provided by the National Institutes of Health, The Foundation Fighting Blindness, The Ruth and Milton Steinbach Fund, the Ronald McDonald House Charities and the Macular Vision Research Foundation.