A new study by the National Eye Institute (NEI) has identified three new genes associated with age-related macular degeneration (AMD). AMD, which is the most common cause of vision loss in people over the age of 60, destroys the macula, a cluster of light-sensitive cells in the central part of the retina. The macula allows for crisp central vision and the perception of fine detail.
The NEI study, which was published online in the Proceedings of the National Academy of Sciences, found the strongest AMD genetic association in a region on chromosome 22, near the gene metalloproteinase inhibitor 3 (TIMP3). Mutations in the TIMP3 gene are linked to Sorsby’s fundus dystrophy (SFD), an early form of macular degeneration.
The two other genes associated with AMD – human hepatic lipase (LIPC) and cholesterol ester transfer protein (CETP) – were found in the high-density lipoprotein (HDL) cholesterol pathway. HDL is part of the lipoproteins family, which transport lipids such as cholesterol through the bloodstream. The study’s authors believe that early stages of AMD are affected by accumulation of oxidation products of cholesterol and other lipids in the retinal pigment epithelium.
“Very exciting news has been released on the discovery of three new genes that are associated with age-related macular degeneration,” says Dr. Bruce Rosenthal, Chief of Low Vision Programs at Lighthouse International. “Two of the genes are involved in the cholesterol pathway and may open the way for new treatments that lead to stabilizing, as well as improving vision in persons with the wet as well as the dry form of the disease. This is a very important step, since age-related macular degeneration accounts for 54 percent of the cases of legal blindness among white Americans.”