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Discovery of mutant gene, may lead the way to new AMD treatments.
According to a paper published online on Monday, March 6 in Nature Genetics, age-related macular degeneration (AMD), may be attributed to two genes.
Professor of Ophthalmology Dr. Greg Hageman says that three out of every four cases of AMD start when a protein from one of two genes fights off bacteria in the eye, the problem comes when the protein does not stop fighting and begins damaging the macula.
It has been reported that AMD affects one in ten people over 60 in the U.S. As many as 50 million people worldwide are estimated to be irreversibly blinded by the condition. It appears that 74% of AMD patients have such genetic mutations.
Hageman and others believe the discovery could lead to new ways to treat diminishing sight and may suggest new drugs that could slow or prevent the damage to the retina that progressively occurs in AMD.
There is clearly a genetic component in AMD, recent research has linked several variants of a gene known as Factor H to an increased risk of developing AMD. Factor H produces a protein that helps to shut down the immune response to bacterial or viral infections once the invading pathogens have been eliminated, preventing damage to healthy tissue. Mutations in Factor H apparently causes unusual inflammation that then damages the macula.
The Factor H gene alone only explains between 30 and 60 per cent of AMD cases, and a third of people with the mutation do not develop the disease. As a result, researchers have continued to look for additional genetic information that would explain this.
Genetic analysis of about 1300 people revealed the role of factor B and complement component 2 (C2) genes that may have a protective role in AMD. Factor B starts the immune response, as opposed to Factor H that starts it. Certain variants of Factor B appear to protect the eye when a person has a harmful Factor H mutation.
This research suggests that mutations of Factor H and Factor B account for 74 per cent of AMD cases.
The specific triggers that set off the immune response and subsequent inflammation are still unknown.
Researchers at various institutions including Dr. Hageman’s team at the University of Iowa are now looking for viruses and bacteria that might be the culprits.
Finding the root cause of advanced macular degeneration does not mean a cure is around the corner but doctors believe this new information can still help.
Hageman said, "Even if we buy those folks 5 or 10 years of additional vision, we're doing them a great service."
The research is published in the journal Nature Genetics.
