October 6 (HealthDay News) -- Variants in the gene that helps produce vital proteins in the eye have been linked to age-related macular degeneration (AMD), a major source of blindness, a new report says.

Visual impairment or blindness from AMD is common in people over age 80 in developed countries. In fact, a previous study found that nearly two-thirds of this age group has some sign of the disease.

Reporting in the online edition of The Lancet, researchers from the University of Southampton in the United Kingdom linked AMD to the SERPING1 gene. This gene is involved in production of proteins for the system that helps clear foreign material and infection from the eye.

They identified a single variant in the SERPING1 gene where frequencies of the variant forms were significantly distorted in British patients with AMD.

The findings were replicated in a separate study done with American patients. A secondary high-density analysis then uncovered five more variants in the SERPING1 gene tied to AMD.

"Genetic variation in SERPING1 may implicate the classic pathway of complement activation in AMD," study researchers Sarah Ennis and Andrew Lotery of the university wrote in the article. "Our findings add to the growing understanding of the genetics of age-related macular degeneration, which should ultimately lead to novel treatments for this common and devastating disease."

SOURCE: The Lancet, news release, Oct. 6, 2008