Macular degeneration has a strong genetic link

By Megan Rauscher

NEW YORK (Reuters Health) - A new study has fount that a specific form of the apolipoprotein E (APOE) gene, called E2, increases the risk of age-related macular degeneration well beyond the age of 65, whereas another form of APOE called E4, may confer some protection.

"Previous studies that have examined the possible link between APOE and age-related macular degeneration have suggested an association but only confined to younger...patients," Dr. Tien Y. Wong, from the Centre for Eye Research Australia, University of Melbourne told Reuters Health.

"The current study suggests that there is a genetic influence on the development of age-related macular degeneration, even in older people," Wong said.

To investigate, the researchers evaluated the relationship between APOE genotype and age-related macular degeneration in 2,170 white and African American subjects who were 65 year old or older and living in one of four US communities.

A total of 336 subjects had "early" age-related macular degeneration and their average age was 79.9. Twenty-eight had "late" age-related macular degeneration and their average age was 82.2 years. The remaining 1,806 did not have the condition.

After accounting for the influence of age, sex, cigarette smoking and other potentially confounding factors, white adults carrying APOE-2 had a 2.5-fold higher likelihood of developing late age-related macular degeneration. On the other hand, white adults carrying the APOE-4 allele had a 31 percent lower risk of developing late age-related macular degeneration, but this relationship was not statically significant.

There were too few cases of late age-related macular degeneration in African American subjects for analysis.

The current findings, the researchers conclude, indicate that mutations of APOE may still have a significant role in the development of late macular degeneration in old age.

SOURCE: Archives of Ophthalmology, January 2007.