An international group of investigators has identified seven new genetic regions associated with age-related macular degeneration (AMD), a common cause of blindness in older individuals. The findings, reported online March 3 in Nature Genetics, could point to new biological pathways and therapeutic targets for AMD.
The AMD Gene Consortium, a network of 18 research groups supported by the National Eye Institute, also confirmed 12 genetic loci identified in previous studies. The study represents the most comprehensive genome-wide analysis of genetic variations associated with AMD.
The consortium's efforts have now explained up to 65 percent of the genetics of AMD, said Jonathan Haines, Ph.D., director of the Vanderbilt Center for Human Genetics Research.
In addition to genetic causes, which may account for about half of all cases of AMD, risk factors include age, smoking, high blood pressure, obesity and diet.
"We're getting closer and closer to understanding the full list of risk factors for AMD," said Haines, one of the lead authors of the study and principal investigator of the coordinating center for the consortium.
AMD is a progressive neurodegenerative disease that kills photoreceptor cells in the macula - the region of the retina responsible for sharp, detailed central vision. As AMD advances, it robs individuals of the central vision necessary for everyday activities like reading, driving, watching television and identifying faces. About 2 million people in the United States have advanced AMD, according to the National Eye Institute.
Haines and others discovered the first genetic risk factor for AMD in 2005 - a gene called Complement Factor H, which is involved in inflammatory signaling pathways. Since then, researchers have identified a number of other genetic loci associated with AMD, but the studies usually involved small numbers of individuals.
"It was very clear that if we wanted to make real progress in understanding the genetics of AMD, we needed to pull all of these various datasets together - which is what the AMD Gene Consortium has done," Haines said.