With a new enzymatic discovery, scientists are understanding the cause of an untreatable eye disease and hope to test breakthrough therapies within a year.
Geographic atrophy is an advanced form of macular degeneration, and the enzyme DICER1 has been implicated in the development of this form of blindness.
This week, scientists report that in people with geographic atrophy, DICER1 is less active in the retina (the light sensitive tissue at the back of the eye where the macula is).
The international team of scientists noticed that this reduced activity is linked to the accumulation of Alu RNA – toxic pieces of genetic material that cause death to retinal cells.
DICER1 stops Alu RNA’s detrimental effects. When they turned off the gene that makes the enzyme in mice, cells in their retina became damaged.
“First, we need to identify various classes of molecules that can either increase DICER1 levels or block Alu RNA so that these can be evaluated in clinical trials,” he explains. "Second, we need to understand more about the biological processes that lead to reduction in DICER1 levels and the precise source of the Alu RNA transcripts."
The exact cause of macular degeneration is unknown, but people over 75 have a 30% risk for the disease. Other risk factors include smoking and obesity.
Drugs that bump up levels of the enzyme will be tested on patients within a year, the Telegraph reports:
Ambati has created two treatments that could potentially halt the march of the disease. One works by boosting levels of DICER, the other breaks down the toxic Alu RNA. The University of Kentucky has applied to patent the techniques and the first trials on people could start by the end of this year.
The study was published in Nature yesterday.
Images: Normal vision (top) and as viewed by a person with age-related macular degeneration (bottom) / National Eye Institute, NIH