Scientists Have Identified One Of The Genes Implicated In Age-Related Macular Degeneration

October 9, 2008

Adapted from Wellcome Trust

Scientists, supported by the American Health Assistance Foundation (AHAF), have identified one of the genes implicated in age-related macular degeneration, the most common cause of visual impairment in developed countries.

The research, published in the medical journal, Lancet, adds to the growing understanding of the genetics of age-related macular degeneration (AMD), which the researchers believe should ultimately lead to novel treatments for the disease.

Almost two-thirds of people aged 80 years or older are affected by AMD to some degree, with more than one in ten left visually impaired by the disease.

Researchers have previously identified a number of other genes or genetic loci (regions of the genome) that affect a person's susceptibility to the disease. Now, researchers at the University of Southampton have shown that a particular variant of the gene SERPING1, carried by just under a quarter of the population, appears to offer protection against the disease.

The University of Southampton team and colleagues from the University of Iowa found evidence of proteins expressed by SERPING1 in the retina and the choroid layer (the vascular layer next to the retina), the two areas affected by AMD. These proteins are involved in regulating a part of the body's innate immune system known as the "complement system." The findings suggest that the complement system is malfunctioning, attacking the retina and choroid layer.

The complement system, under healthy conditions, attacks invading pathogens by producing holes in the membranes of the invading cells. It is described as being part of the ‘innate,’ immune system since it does not adapt to prior exposure to a pathogen. Other types of immunity are consider ‘active’ immunity and are characterized by the more familiar antibody responses that help a body respond more strongly to diseases that it has experienced before. During macular degeneration this complement immune defense is turned against the eye and begins attacking the cells of the retina. In order to develop therapies against a phenomenon required to protect cells against pathogens has proven difficult, and requires a thorough understanding of how the complement system is activated during AMD. Scientists have uncovered several pathways by which complement can be activated. Previous research suggested that one of these pathways was predominantly involved in development of the disease. The current research adds to a growing opinion that more than just one complement pathway, and likely aspects of the active immune system, are involved in development of the disease.

But while this research highlights the complexity of the disease, it also offers new tools that may help researchers understand an individual’s risk for developing macular degeneration. Like other neurodegenerative diseases such as Alzheimer’s disease and glaucoma, also diseases of focus by AHAF, early detection and treatment can slow the progress of the disease and limit the burden of the illness on patients.

On behalf of its donors, the Macular Degeneration Research program of the American Health Assistance Foundation, is proud have funded Dr. Lotery for this very important work and congratulates him on the recognition his group received in this prestigious scientific journal. When asked about the value of AHAF support, Dr. Lotery offered the following comment that illustrates how important our donors’ commitment is to stimulating innovation in medical discovery:

“Support from AHAF has allowed me to push forward several exciting research projects related to macular degeneration. Preliminary findings for two of these projects have been positive and the third project, described here, has identified an important new association of a genetic defect and macular degeneration. This progress should enable me to proceed quickly to obtain further governmental or corporate funding to expand this very important work.”

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