Variations in two genes could account for three-quarters of all cases of age-related macular degeneration, a new study reports.
The disease is the leading cause of blindness in people over 60 and affects more than 50 million people worldwide. It occurs when light-sensing cells malfunction in a part of the retina called the macula and block the central field of vision.
Last year, a team led by Columbia University researcher Rando Allikmets reported that certain forms of a gene for a protein called factor H can increase a person's risk of age-related macular degeneration. Other versions of this gene seem to protect a person from the disease. Factor H shuts off inflammation throughout the body once an infection is eliminated and the immune reaction is no longer needed.