Dr. Ronald Klein, of the University of Wisconsin School of Medicine and Public Health, and colleagues describe the relationship of age and risk alleles (variant gene forms) with the incidence and progression of age-related macular degeneration (AMD) during a 20-year period. They conclude the overall five-year incidence of early AMD was 9.1 percent and late AMD was 1.6 percent.
AMD is a leading cause of vision loss and an increasing number of studies have examined the relationships between AMD candidate genes and their interactions with environmental and host risk factors. Few long-term studies have examined the relationships of these genetic risk factors along the continuum of the disease from its earliest to its most advanced stages, according to the study background.
Klein, professor of ophthalmology and visual sciences, looked at the relationships of variant genes in complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) with the incidence and progression of AMD during a 20-year period in the Beaver Dam Eye Study.
In the study, 4,282 individuals between the ages of 43 and 86 years at a baseline examination in 1988-1990 were enrolled and participated in at least one examination spaced five years apart during the 20-year period. Of this group, 66 percent were classified as low-risk; 26 percent medium-risk and eight percent high genetic risk for AMD.
The study results indicate that almost half – 46.5 percent – of those in the high genetic-risk group went on to develop early AMD even though they did not have AMD at baseline. About 33 percent of those in the low-risk and 39.9 percent in the medium-risk group were estimated to have developed early AMD.
For late AMD, 15.3 percent of those affected were estimated to have developed the disease by age 80. Only 1.4 percent of the low-risk group and 5.2 percent of the medium-risk group developed late AMD.
“These population-based data provide estimates of the long-term risk of the incidence and progression of AMD and its lesions by age and genetic risk alleles for CFH and ARMS2,” the study concludes. The authors also note that when early AMD is present, using retinal photographs to grade the presence and severity of AMD creates a more accurate risk assessment than knowing only the genetic risk based on the two AMD genes.
The article was published Online First today by Archives of Ophthalmology, a JAMA Network publication.
University of Wisconsin School of Medicine and Public Health