Researchers say their discovery of a gene linked to age may lead to a simple test for diagnosing those most at risk for macular degeneration. The condition is the leading cause of untreatable blindness in the elderly.

Scientists at the University of Pittsburgh discovered the gene, variants of the gene called PLEKHA1. They say they hoped it could lead to more preventive strategies for the condition. Results of their 15 years worth of study are set to be published in the September issue of the American Journal of Human Genetics.

Approximately 10% of patients 66 to 74 years old will develop macular degeneration; the prevalence rises to 30% in patients 75 to 85, according to experts. Age-related macular degeneration currently affects 1.75 million people, with the number expected to rise to 3 million by 2020, according to researchers at Johns Hopkins University and with the Eye Diseases Prevalence Research Group.