A Deeper Understanding of Age-related Macular Degeneration (5/3/2007)

According to a new study led by Tufts' Johanna Seddon, M.D., Sc.M, the progression of age-related macular degeneration can be linked to genetic and environmental factors.

Boston [04.30.07] For the millions of people with age-related macular degeneration, two common gene variations can predict their risk of developing a more advanced form of the disease, according to a new study led by Tufts' Johanna Seddon, M.D., Sc.M. The research—published in the Journal of the American Medical Association (JAMA) and widely reported by the media—also shows that smoking and being overweight can increase a person's risk of losing vision as a result of the disease, which can also cause blindness.

"The two genetic variants are related and predict to a certain extent which individuals who have earlier-intermediate forms of macular degeneration progress to the advanced form and visual loss," Seddon, a lecturer in Tufts School of Medicine's department of ophthalmology, told HealthDay News. The disease, which damages the part of retina responsible for central vision, affects six million Americans, while nine million more are at risk, reported Newsday.

Over a six year period, Seddon and a team of researchers studied 1,500 patients, ages 55-80, who were in the early stages of macular degeneration. Conducted between 1995 and 2001, Seddon's study showed that people with variations in the genes CFH and LOC387715 were at an increased risk for having their maculas degenerate to the point of visual impairment.

According to HealthDay, people with the CHF variant are 2.6 times more likely to have the disease progress, while the risk of progression for those with the LOC387715 variant is 4.1 times higher.

While CHF and LOC387715 have been previously associated with the disease, the publication reported that prior "studies exploring this relationship had been cross-sectional in nature, not prospective as the current one is."

"Genetic variants are part of the way we can differentiate who gets worse, coupled with environmental factors like a high body mass index and smoking," Seddon told HealthDay.

While the results of the study appear to give researchers more clues about the progression of the disease, she explained that additional research is needed.

"Some individuals who progress do not have these genetic variants or have never smoked," Seddon told HealthDay. "We need to refine this predictive measure, add more genetic variants and maybe even more environmental factors."

With more to learn about the risk factors associated with the progress of the disease, Seddon stopped short of endorsing the idea of screening patients with early age-related macular degeneration for the gene variations.

"It is premature to do screening because the story is still unfolding," she told Newsday.

Note: This story has been adapted from a news release issued by Tufts University

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