Genes play important role in macular degeneration

Reported by Susan Aldridge, PhD, medical journalist

A new study shows genetic influences are relevant to three out of four cases of age-related macular degeneration.
Around 50 million people around the world are affected by age-related macular degeneration (AMD), the leading cause of blindness in older people. Now a team at Columbia University Medical Center reveals that 75 per cent of cases of AMD are actually influenced by variations in two different genes.

The first of these, known as Factor H, codes for a protein involved in the immune response to inflammation. The second, Factor B, is related but acts in the opposite way. The researchers believe that some variants of Factor B and Factor H may protect from AMD, but they did not find these in their genetic analysis of 1,300 people. Instead, they found variants that seemed to promote the disease. It is unusual to find a genetic influence in as many as 75 per cent of cases of a disease.

The findings suggest that AMD is caused by some trigger that leads to inflammation that is not damped down, because of the gene variants influencing the immune pathway in an adverse sense. We do not know what this trigger is - but there has been great progress in understanding how AMD works in recent years and this study is just the latest example. It is to be hoped that the research will soon lead to effective new treatments.

Source
Nature Genetics 5th March 2006

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