Researchers have discovered a molecular mechanism implicated in age-related macular degeneration, the major cause of untreatable blindness in the industrialized world. The news is getting some attention in the mainstream media.
The research was led by University of Kentucky ophthalmologist Jayakrishna Ambati and published online in the journal Nature. This study also elaborates, for the first time, a disease-causing role for a large section of the human genome once regarded as non-coding "junk DNA."
Geographic atrophy, a condition causing the death of cells in the retina, occurs in the later stages of the dry type of macular degeneration, a disease affecting some 10 million older Americans and causing blindness in more than 1 million. There is currently no effective treatment for geographic atrophy, as its cause is unknown.
Ambati's team discovered that an accumulation of a toxic type of RNA, called Alu RNA, causes retinal cells to die in patients with geographic atrophy. In a healthy eye, a "Dicer" enzyme degrades the Alu RNA particles.
Along with the discovery, Ambati's laboratory developed two promising therapies to prevent the condition. The first involves increasing Dicer levels in the retina by "over-expressing" the enzyme. The second involves blocking Alu RNA using an "anti-sense" drug that binds and degrades this toxic substance. Ambati's group is preparing to start clinical trials by the end of this year.
"These findings provide important new clues on the biological basis of geographic atrophy and may provide avenues for intervention through preventing toxic accumulation of abnormal RNA products," Dr. Paul Sieving, director of the National Eye Institute, said in a prepared statement.
- read the University of Kentucky release
- look at the abstract in Nature