Gene Tied to Age-Related Blindness

Three independent studies published in the 11 March issue of Science Express (Klein et al., Edwards et al., and Haines et al.) have identified a gene involved in a form of eye damage that is the leading cause of blindness in the elderly. This findings may lead to tests that would allow earlier detection of the disorder, known as age-related macular degeneration or AMD, which in turn may lead to better treatments.

In patients with AMD, the central region of the retina deteriorates, leading to loss of central vision. No therapy has proven to be broadly effective. Three research teams scanned the genomes of individuals with and without AMD in search of patterns that could be linked to the disorder.

Robert Klein and colleagues examined more than 100,000 sequence variants (known as single nucleotide polymorphisms or "SNPs") across the entire genome and were able to identify a specific variant in the CFH gene that was strongly tied to AMD. They estimate that this variant increases an individual's risk of developing AMD by three- to seven-fold. The CFH gene encodes a protein called complement factor H that helps regulate inflammation in a branch of the immune system known as the complement system.

The CFH gene lies in a section of chromosome 1 that had already been associated with AMD in studies of families prone to the disorder. Two other research teams, Albert Edwards and colleagues, and Jonathan Haines and colleagues, focused on this region for their studies. Both groups sorted through the SNPs on this portion of the chromosome and identified the same variant as Klein's group did. Collectively, the three studies indicate that this variant form of complement factor H may account for 20 to 60 percent of all AMD cases. Stephen Daiger discusses these findings in a related "Perspective."

— Kathy Wren

14 March 2005