Common blindness in elderly has genetic link: US studies (AFP)

WASHINGTON (AFP) - Scientists have identified a genetic link to macular degeneration, a discovery that could lead to early identification and treatment of the main cause of blindness among the elderly, researchers said.

Age-related macular degeneration (AMD) is an affliction which blurs the vision in the macula, the part of the eye which perceives the details at the center of one's vision.

Common in people above 50 and affecting an estimated 15 percent of those reaching 75, sometimes leading to complete blindness, there is no effective treatment yet for AMD.

Three teams of researchers in the United States examined the entire genome of AMD sufferers and compared them to those who were not beset with the affliction.

A team led by Robert Klein of Rockefeller University in New York which published their findings in Science Magazine examined more than 100,000 variations of gene sequences to identify a specific variation in the gene CFH, located in a region of chromosome 1 which is strongly connected to AMD.

The team estimated that this variation could increase the risk of developing AMD in an individual by three to seven times.

Two other research teams, one led by Albert Edwards of the University of Texas at Dallas, and the other by Jonathan Haines of Vanderbilt University Medical Center in Nashville, Tennessee, were able to confirm the conclusions of Klein's team in their own examinations of chromosome 1.

Together the three studies suggest that this genetic variation could explain from 20 percent to 60 percent of AMD cases.