Genes Not Very Helpful in Predicting Age-Related Macular Degeneration
A new, 20-year-long study shows that much more research into genetic and environmental factors is needed.
-- by Michael Harkin
Age-related macular degeneration, or AMD, is one of the foremost causes of vision loss, especially in people over the age of 65. Although there have been studies that take a look at genetic and environmental risk factors for AMD and how they relate, the relationship between these factors had not previously been extensively studied in patients over a long period of time.
A new study, published Online First in Archives of Ophthalmology and conducted by Dr. Ronald Klein, M.D., M.P.H. of the University of Wisconsin School of Medicine and Public Health and colleagues, examined age and risk alleles (variant gene forms) as they relate to the occurrence of AMD, as well as how the condition progresses, over a 20-year period.
The findings showed that genetic risk factors were not very helpful in terms of predicting the progression and incidence of the disease. Instead, what turned out to be more helpful were actual ophthalmological examinations once early signs of AMD occurred.
The Expert Take
Klein said in a podcast on the Archives of Ophthalmology website that the study demonstrated that genes were not particularly helpful for predicting the risk of developing AMD or the possible progression of the condition.
“Genes are not very helpful in predicting progression to late AMD in a 45-year-old with no signs of AMD,” said Klein in the podcast. “Once the early signs are there, just looking at them ophthalmoscopically will help you estimate development of late AMD much better than the genes themselves. So while the genes are important in terms of understanding causes of the disease, in terms of individual risk assessment, they have less importance at this point in time.”
Source and Method
The study, which was called the Beaver Dam Eye Study, took place in the city of Beaver Dam, Wisconsin, which was chosen for its representativeness of the larger population. It involved 4,282 patients between the ages of 43 and 86. The first examinations took place between 1988 and 1990, and each participant was examined five years apart over a 20-year period.
Incidence of AMD was studied from its earliest signs to its latest stages. Photographs were taken of the back of patients’ eyes, and various measurements were taken to measure incidence and progression. Age, sex, and presence of high-risk genes were considered.
It was found that 66 percent (2,820 patients) had low risk of AMD, 26 percent (1,129 patients) had intermediate risk, and 8 percent (333) had high risk. In the study group, there was a 9.1 percent incidence of early AMD, and a 1.6 percent incidence of late AMD. Incidence increased with age. However, it did not tend to occur more in one gender than the other.
“Cessation of smoking, changes in diet, and physical activity must be recommended to reduce the incidence and progression of AMD,” said Klein in the accompanying podcast. Additionally, suggested Klein, the findings suggest that those at risk of AMD not use genetic testing to show what their risk is. If early AMD signs develop, ophthalmological assessment will be much more effective in terms of examining risk and progression of the condition.
Klein went on to say that additional research is needed into gene and environment interaction, as well as common risk factors like smoking. Additionally, more specific genes related to AMD need to be uncovered and examined.