Off the Cuff: Advancements in AMD Genetic Testing
One of my most favorite courses I took in undergrad was a genetics course. I found it absolutely fascinating. How the combination of DNA sequences sometimes occurred perfectly or sometimes in error with those errors (or mutations) having no effect, with wildly detrimental effects, or in some instances when it benefited the organism felt like puzzles that needed to be solved. When the 23andMe and Ancestry websites started offering genetic testing, I did both of them knowing they’d obviously have the same genetic sequence from me, but I wanted to see the different analysis each group applied. I had my siblings, parents and remaining grandparents do it too. I could see which segments I got from each parent and grandparent as well as what I shared with my brother and sister. If I had had any idea at that time that genetic counseling was a career option, I may have been on an entirely different life path.
Where Ancestry’s site uses the data to help you build family trees and track migration of populations over time, 23andMe which also has an ancestry component looks more at health-related risk factors. Some of the information wasn’t exactly earth shattering. I had a high likelihood of having brown hair, brown eyes, and a cleft in my chin, but I did have a “slightly increased risk” for a couple of conditions such as diabetes and Alzheimer’s that I already knew some of my relatives had. The data stating low, slight, or at-risk for one condition or another wasn’t exactly inspiring to cause change. This single data point didn’t take into account other lifestyle and risk factors that could contribute to these disease states. Some retina specialty associations do not recommend genetic testing for macular degeneration due to that one data point not taking lifestyle and other risk factors into account. That’s exactly how I viewed the genetic testing available for macular degeneration until recently.
At the American Optometric Association meeting in Nashville this year, I was introduced to the AMDiGuard genetic test by Visible Genomics for macular degeneration. This test was different, using the data from a cheek swab and from a patient’s various risk factors such as smoking status, race, gender, BMI, age and current level of macular changes, to determine if your patient is low, moderate or high risk for developing advanced macular degeneration such as geographic atrophy or choroidal neovascularization. Secondly, based on this information, this test also gives a percentage risk of advancing in 2, 5, 10, 20 and 30 years. Additionally, research published in 20151 showed that in individuals with particular combinations of alleles, zinc could have no effect, be beneficial, or actually make the macular degeneration progress quicker. This is incredibly much more useful information to give patients to direct them towards supplementation appropriate for them. This has become a great tool for patients showing early signs of macular degeneration as well as patients who have family members with macular degeneration and want to know their risk and what they can proactively do.
1.Awh CC, Hawken S, Zanke BW. Treatment response to antioxidants and zinc based on CFH and ARMS2 genetic risk allele number in the Age-Related Eye Disease Study. Ophthalmology. 2015 Jan;122(1):162-9. doi: 10.1016/j.ophtha.2014.07.049. Epub 2014 Sep 4. PMID: 25200399.
Shannon L. Steinh?user, OD, MS, FAAO
Chief Medical Editor