National Institutes of Health (NIH) investigators suggest changes in how genes in the immune system function may result in age-related macular degeneration. AMD is the leading cause of visual impairment in older adults, based on their preliminary research.
AMD is an eye disease with its onset usually after age 60 that progressively destroys the macula, the central portion of the retina, impairing central vision. It rarely causes blindness because only the center of vision is affected. However, injury to the macula in the center of the retina can impair the ability to see straight ahead clearly and sometimes make it difficult to perform other daily activities that require fine central vision.
A chemical reaction that switches off genes is called methylation and decreased levels of DNA methylation can cause harmful effects on the interleukin-17 receptor C gene (IL17RC). The lack of DNA methylation led to increased gene activity and, in turn, increased levels of IL17RC proteins in patients with AMD. IL17RC is a protein that promotes immune responses to infections, such as fungal attacks.
Many studies support that IL17- and IL17RC-mediated immune responses can be crucial in causing AMD. And by measuring IL17RC gene activity in at-risk patients, we have also potentially identified an early method to detect AMD.
The disease is actually incurable but treatments exist to prevent severe vision loss in certain types of advanced AMD. There are 2 million Americans are now suffering from advanced AMD while 7 million have intermediate stages.
Changes in DNA methylation have been implicated in cancer, lupus, multiple sclerosis, and many other diseases. This is another warning why we should take good care of ourselves but recent studies have identified several genes with alterations that increase the risk of developing the disease. However, environmental risk factors have also been suggested as possible causes of the disease. One explanation may be that environmental exposures can also be a cause to DNA methylation, which regulates gene expression. Changes in this process may result in the production of too much or too little of a gene’s protein, leading to cellular dysfunction and disease.