Anyone can develop age-related macular degeneration (AMD).
Doctors aren’t yet sure exactly what causes it. But things like your diet and lifestyle might affect your chances of developing it. And for nearly 3 out of every 4 people with AMD, genes are a big influence on if, when, and how the disease presents itself.
What Role Do Your Genes Play?
AMD often runs in families. In fact, you’re three times more likely to get AMD if you have a first-degree relative with it. It’s also more common among certain ethnic groups, such as people of Asian or European descent.
Experts have identified over 30 genes linked to the risk of getting AMD. If many people have a certain variation of a gene and also have AMD (and people without the gene variation don’t have AMD), then doctors say that gene variation is associated with AMD.
These genes include:
- Factor H and Factor B. These genes code for your immune system proteins that help regulate inflammation. Nearly 74% of people with AMD have one or both of these genes.
- PLEKHA1. Also related to inflammation, this gene is on chromosome 10. Having it increases your risk of getting AMD.
- LOC387715. If you have this gene and you smoke, your risk of getting AMD goes up even more.
- HTRA1. A mutation in this gene increases your chances of getting AMD. Experts have identified a link between this mutation and the formation of drusen, the yellow waste deposits under the retina you can get in the dry type of AMD. It can also promote the growth of new blood vessels in the wet type of AMD.
- Complement C3. A variant of this gene raises your risk of both wet and dry AMD.
Two genes in particular are strongly connected with how your AMD progresses. Your have a higher risk of getting the disease if you have one of these variants:
- A group of genes called the complement cascade on chromosome 1. This group of genes controls proteins that work in your immune system to protect you against bacteria and viruses. If they target the wrong cells -- like cells in the retina -- it can cause damage.
- ARMS2/HTRA genes on chromosome 10. Scientists aren’t yet exactly sure what these genes do to influence your development of AMD, but the connection between the two is strong.
Having these genes doesn’t mean you’ll automatically get AMD. It only means your risk is higher than people who do not have the genes.
It’s also possible to have certain genes that lower your risk of getting AMD. Environmental factors also contribute to whether you get the disease.
Can Your Genetic Risk of AMD Be Caused by Other Conditions?
People with diabetes have a higher risk of developing AMD, especially if they have diabetic retinopathy. That’s a complication of diabetes that causes weakness in the blood vessels in your eye. Your risk for AMD goes up more if, along with diabetes, you’re obese or you have high blood pressure or high cholesterol. But research shows that taking metformin, a common treatment for diabetes, may lessen these risks.
Your genes play a role in the development of diabetes. But researchers are still studying whether these genetic factors overlap with any of the genetic factors that increase your chances of AMD. There are some shared biological pathways that both use, and those could provide some clues.
Potential for Gene Therapy
Researchers haven’t yet developed gene therapy to help treat or prevent AMD. What they’re learning about the genes involved in AMD will help develop new tools for protective action, diagnosis of the disease, and treatment down the road.
It’s possible to have genetic testing done to see if you have any of the genes associated with AMD, but the American Academy of Ophthalmology doesn’t recommend it. Without gene therapy, knowing which genes you have that increase your risk doesn’t help with treatment.
DNA sequencing technology has also traditionally been very expensive and lengthy, although costs and time are decreasing. Doctors may turn to it in the coming years as it becomes more practical and useful, especially if you’re in a higher risk category.
Understanding more about which genes are involved in AMD helps doctors understand the condition itself better, which may lead to other advancements in prevention and treatment.
A family history of AMD is a good indicator that you might have one or more of these risk-increasing genes. Be sure to eat a diet rich in fruits and leafy green vegetables, eat fatty fish twice a week (salmon, tuna, sardines, mackerel), and avoid red meat. If you smoke, quit. Your doctor may also recommend a special vitamin formula called AREDS 2 if you’re at high risk for, or have early signs of, AMD.
Experts recommend you keep up with regular eye appointments so that you’re screened for symptoms and get early treatment if you get a diagnosis.