BOSTON (Mar. 3) - Tufts Medical Center researchers and collaborators have found seven new genetic locations with genome-wide statistical significance that increase the risk of age-related macular degeneration (AMD), the leading cause of blindness in people over age 65. One of these seven genes, COL8A1, was previously reported to be associated with AMD by the Tufts Medical Center team in 2010 and 2011.
“This new information adds to our understanding of the biology of the disease and may possibly lead to new treatments,’’ said Johanna M. Seddon, MD, ScM, Director of the Ophthalmic Epidemiology and Genetics Service at the New England Eye Center at Tufts Medical Center and Professor of Ophthalmology at Tufts University School of Medicine.
Age-related macular degeneration, or AMD, affects more than 1.75 million people in the United States today. Because the population is aging, that number is expected to climb to 3 million over the next seven years, according to the National Eye Institute. The disease robs people of sight by destroying the macula, a sensitive part of the retina that is responsible for central vision, the type of vision you need to read or do other detailed work. AMD primarily affects people over 50 years old. While environmental factors also play an important role, genetic risk factors are thought to account for up to 70 percent of the risk of developing the advanced forms of the disease, based on a national twin study previously conducted by Seddon.
The team of five Tufts Medical Center researchers formed one of four analysis teams and Seddon was the leader of the Phenotype Committee in a large international effort to conduct the largest genome-wide association study to date for AMD. The study, published March 3rd on-line in Nature Genetics, pooled data from a large genome-wide association study conducted at Tufts Medical Center and other studies conducted around the world to look for associations between particular genetic locations and an increased risk of age-related macular degeneration. In all, the researchers analyzed data from more than 17,100 patients with the disease and 60,000 controls without known AMD.
They found six new genetic areas that are associated with an increased risk of developing the disease. They also confirmed the statistical significance of the previously identified genetic location reported by the Tufts team. This new data raises the total number of loci implicated in the development of AMD to 19 different genes. The Tufts researchers lead by Seddon previously discovered the relationships between macular degeneration and several other genes in pathways involving high-density lipoprotein cholesterol (HDL-c), complement and immunity, collagen and extracellular matrix and angiogenesis, all of which were confirmed in this large international study.
The new genetic locations are in similar pathways: inflammation, immune defenses and atherosclerosis signaling. The new information gives researchers more targets for the development of new drugs or other therapies. It should also help them determine how alterations in those genetic pathways increase or decrease risk of developing AMD.
“We’ve identified new genetic variants that increase your susceptibility for developing AMD,’’ said Seddon. “The next step is to refine these results further and search for what we call the causal variants, the causal relationships in these genes that lead to the disease.’’
The research was funded by the National Institutes of Health, private philanthropy and foundations.
About Tufts Medical Center and Floating Hospital for Children
Tufts Medical Center is an exceptional, not-for-profit, 415-bed academic medical center that is home to both a full-service hospital for adults and Floating Hospital for Children. Conveniently located in downtown Boston, the Medical Center is the principal teaching hospital for Tufts University School of Medicine. Floating Hospital for Children is the full-service children's hospital of Tufts Medical Center and the principal pediatric teaching hospital of Tufts University School of Medicine. Tufts Medical Center is affiliated with the New England Quality Care Alliance, a network of more than 1,800 physicians throughout Eastern Massachusetts. For more information, please visit www.tuftsmedicalcenter.org.