Major Eye Disease Linked to Gene

Oct. 19, 2006 -- You may one day be able to take a blood test to find out your risk for age-related macular degeneration (AMD), the leading cause of age-related vision loss.

That's because people with a certain gene variation may be up to seven times more likely to get AMD, a new study shows.

AMD affects the macula, a key part of the eye's retina, and can cause severe vision loss.

The new study appears in Science's early online edition, called SciencExpress.

Researchers included Zhenglin Yang, MD, of the Moran Eye Center at the University of Utah's medical school.

In the future, a blood test might be used to check for the variation of the HTRA1 gene -- the one tied to AMD. "If anyone in your family has a history of macular degeneration, this test would be advised," Yang says in a University of Utah news release.

"The gene is also a critical genetic clue that will allow us to move forward with developing treatments and preventive strategies for patients with AMD," Yang says.

Yang notes that as the population ages, "finding treatments and cures is vital."

Gene Screened

Yang's team screened the genes of 581 AMD patients and 309 people without AMD.

Participants were in their 70s, on average; all were white and at least 60 years old.

The researchers found that a particular variation of the HTRA1 gene was much more common in people with AMD than in those without it.

The HTRA1 gene also stood out in a second AMD study published in the same online issue of the journal.

The second study included 96 AMD patients and 130 people without AMD. All were Chinese adults living in Hong Kong.

The Chinese AMD patients all had the rarer, more aggressive "wet" form of the disease.

In "wet" AMD, abnormal blood vessels grow beneath the macula and leak. "Dry" AMD is marked by tiny yellow deposits beneath the macula, rather than the abnormal, leaky blood vessels of the "wet" form.

A particular HTRA1 gene variation was 10 times more common in the people with "wet" AMD, that study shows.

The Hong Kong study comes from scientists including Andrew DeWan, PhD, of Yale University.

The studies don't rule out the possibility of other genetic influences on AMD.

SOURCES: Yang, Z. Science, Oct. 19, 2006; online SciencExpress edition. DeWan, A. Science, Oct. 19, 2006; online SciencExpress edition.