New Genetic Test Available for AMD
Are you wondering about your risk of developing age-related macular degeneration (AMD)? A new test called MaculaRisk has recently become available in Canada, and it can teach you about the AMD genes in your genetic makeup. If AMD runs in your family, the test can help you to gauge your chances of developing the condition – and may help you take preventative steps now if it turns out you are more at risk. But genetic testing may not be for everyone, and the field is still new. Read on to learn more about this test and the issues surrounding genetic testing for AMD.
Recent discoveries
Over the past four years, international researchers have discovered a number of different genetic markers – small variations in DNA – that can make someone much more likely to develop AMD. For example, some people carry harmful variations of a gene called Complement Factor H (CFH), which helps to control the immune system’s inflammatory response. A harmful variation of the CFH gene can cause inflammation to get out of control in your retina, putting you at greater risk for AMD.
MaculaRisk, a new test that examines eight of the main genetic biomarkers for AMD, has been available in Canada since March 2009 from ArcticDX, a molecular diagnostics company. The test examines these genetic markers along with your smoking history, another major risk indicator.
High and low risk scores
More than 60 per cent of AMD risk is related to genes and another 10 to 20 per cent is related to smoking, according to Dr. Brent Zanke, chief medical officer of ArcticDX.
MaculaRisk cannot tell you definitively whether you will develop vision loss from AMD – even if your risk is considered high, you may not get the condition. But the results of a simple saliva test at an eye doctor’s office can tell you whether your risk is extremely high (5), very elevated (4), elevated (3), average (2) or low (1). “You would have about a 70 per cent risk of losing your vision from AMD if you had all the genetic markers and smoked. If you had none and didn’t smoke, your risk would be less than 5 per cent,” says Zanke.
Would you want to know your genetic risk?
Now that this test is available, it’s important to consider whether you would want to know more about your risk and how you would handle the results. Some people genuinely don’t want to know this kind of information – it may cause them undue worry. If you are one of those people, it’s important to recognize this. After all, you can still do things that may help prevent AMD without taking the test.
Some people do want to know their risk profile. Knowing your risk is high may motivate you to make lifestyle changes to reduce your risk, such as quitting smoking, wearing sunglasses, and eating a healthier diet (see Prevention & Risk Factors in the AMD section on CNIB’s website). Your eye doctor could also monitor you more closely to try to detect and treat AMD earlier, helping to prevent or delay vision loss. “If you are treated early, the outcome is much better than if you wait until later,” says Zanke.
Dr. Alan Cruess, head of ophthalmology and visual sciences at Dalhousie University in Halifax, cautions that genetic testing for AMD is still very new. “ArcticDX has done a good job of getting the main genetic markers for MaculaRisk. But these tests are a work in progress,” says Cruess, who believes that AMD testing isn’t yet ready for widespread use. He is looking forward to further developments in the future, when it may be possible to determine which treatments work best for someone’s particular genetic makeup.
If you decide to undertake genetic testing for AMD, speak to your eye doctor, who will be able to provide professional advice and counselling about the results. Taking genetic tests through companies on the Internet and trying to interpret the results without professional medical advice is not recommended.
MaculaRisk is available from eye care professionals in 120 offices across Canada at an introductory cost of $375 until the fall of 2009.
You can learn more about AMD in these resources from the CNIB webstore: