The macula lies at the centre of the retina and is essential for detailed central vision. Degeneration of the macula interferes with important tasks such as reading and driving.
Age-related macular degeneration (AMD), the cause of which is poorly understood, is the leading cause of visual loss in older people and the commonest cause of blindness in the USA and European countries.
The researchers based their findings on studies of patients with AMD (603 from England and 244 from Scotland) who were compared with 701 unaffected people.
They found that a variant in the complement C3 gene influenced the risk of developing AMD. For the 30% of the population who carry one copy of the so-called ,fast, variant the risk of AMD was increased by 70%, and for the 4% of people with two copies of the ,fast, variant the risk of AMD was more than doubled.
AMD can take two forms called ,wet, (also called choroidal neovascularisation or CNV) and ,dry, (also called geographic atrophy or GA). The ,fast, variant in the C3 gene increases the risk of both forms of the disease.
The complement C3 gene has a central role in the immune system. The results of this research provide strong evidence that inflammation is an important part of the disease process in AMD.
The goal of this type of research is to achieve a full understanding of the causes of AMD, which should lead to the development of better treatment and strategies for prevention of this common and debilitating disease.
Professor John Yates, at the University of Cambridge, said: ,AMD is devastating for those who lose their site and we hope that a better understanding of what causes the disease will eventually lead to better treatment and perhaps prevention.
The initial studies were carried out by a team of researchers led by Professor Yates and Professor Tony Moore at the UCL Institute of Ophthalmology. Further work to confirm the initial findings was carried out by researchers in Scotland led by Professor Alan Wright, Medical Research Council Human Genetics Unit, Edinburgh.
cam.ac
The medical breakthrough is the result of a four-year study led jointly by Dr. Rye and deCODE Genetics scientist Dr. Hreinn Stefansson. With the goal of identifying genes causing RLS, the research team conducted genome-wide scans of nearly 1,000 Icelanders and 188 Americans. A new chip technology was applied along with genome wide association methods.
This approach allowed Drs. Rye and Stefansson to probe more than 300,000 small regions (single nucleotides) distributed across the entire genome for differences more common to RLS sufferers as compared to population-based controls.
According to Dr. Rye, very little is known about the function of the gene variant discovered.
"Additional work will be required to translate this knowledge into a plausible mechanism and, in turn, more rational and better treatments," notes Dr. Rye. "Future advances will depend upon additional monies which to this point have come solely from private foundations and industry."
Dr. Rye says RLS is exceedingly common but not taught as a part of standard medical education, in part leading many medical professionals, educators and academicians to challenge its commonality and authenticity.
emory/ and decode/