Age-related macular degeneration (AMD) is caused by a number of genetic and environmental factors. Genome-wide association studies (GWAS) have identified have previously uncovered genetic factors linked to AMD risk. These studies involve scanning the entire human genome for genetic differences between people with AMD and matched controls. However, the presence of these genetic variants only increases one's risk of developing an advanced form of the disease in the future
Single nucleotide polymorphisms (SNPs)
Most forms of macular degeneration are not linked to any single genetic mutation. Instead, susceptibility to age-related macular degeneration (AMD) is scattered over a number of small irregularities of genes called single nucleotide polymorphisms (SNPs).
SNPs may be inherited or arise spontaneously, and their impact is tempered by other factors, such as age, overall health and nutrition, and exposure to cigarette smoke, sunlight, and other toxins.
Complement is an arm of the immune system that attacks invading bacteria. It is a series of proteins that recognize the bacteria as foreign, then initiate a cascade of events that pokes holes in bacterial membranes and recruits white blood cells to kill them.
Complement can sometimes inappropriately target our own cells, including those in the retina. Among the complement genes, complement factor H confers the greatest AMD risk.
While ARMS2/HTRA is the subject of intensive research, the role of these genes in AMD is not yet understood.
Explore More of Our 360° Approach
- Retinal Pigment Epithelium
- Geographic Atrophy
- Cell Metabolism
- Immune Response
- Diet and Nutrition
- Regenerating Cells
- Innovative Treatment Approaches
Retinal Pigment Epithelium
It is generally thought that age-related macular degeneration (AMD) begins in the retinal pigment epithelium (RPE), a single layer of cells next to the retina, whose job is to transport molecules in and out to nourish the retina and dispose of waste. The RPE’s ability to do its job can be compromised by age, oxidative stress, inflammation, and other factors causing the immune system to kick in and overact.
Some patients with age-related macular degeneration (AMD) will develop geographic atrophy (GA), which refers to patches or regions of the retina where cells waste away and die (atrophy). Sometimes these regions of atrophy look like a map to the doctor who is examining the retina, hence the term geographic atrophy.
The retinal pigment epithelium (RPE) is a single layer of cells at the back of the eye next to the retina. The health of RPE cells, and their ability to support the nerve cells of the retina, depend on well-functioning RPE cell metabolism as a source of energy.
The immune system is designed to fight off infections. To do this, it must be able to tell the difference between our own cells (and leave them alone) versus invading bacteria or viruses (and attack them). As we age, our cells are altered by “oxidative” damage and accumulation of debris (i.e environmental toxins like sun, chemicals, tobacco smoke, and other pollution) , which can cause the immune system to attack its own cells.
Diet and Nutrition
Research shows there is a strong link between dietary patterns and age-related macular degeneration (AMD).
People with diets that are elevated in fat, cholesterol and high glycemic index foods, and low in antioxidants and green leafy vegetables may be more likely to develop AMD.
Unlike skin and other parts of the human body, the nerve cells of the eyes do not, for the most part, regrow or regenerate after damage has occurred. However, there is new hope. Work is moving forward to regenerate and reconnect the eye’s retinal cells that have been damaged by age-related macular degeneration (AMD), and to restore the underlying retinal pigment epithelium (RPE) cells that provides its nourishment and support.
Innovative Treatment Approaches
One day, we may be able to detect signs that age-related macular degeneration (AMD) is developing and take early steps to defend against it. Macular Degeneration Research is funding research into unique ways to protect the retinal pigment epithelium (RPE) and retina at earlier stages, before damage to sight has occurred.
The red cone photoreceptor:
Cone photoreceptors, like the one shown in red, are responsible for high-definition central vision, the kind lost in macular degeneration. (Courtesy of Mrinalini Hoon, PhD, and Raunak Sinha, PhD, University of Wisconsin-Madison).