EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/146899
18 EW CATARACT July 2013 Cataract editor's corner of the world The current state and potential of AMD genetic testing by Ellen Stodola EyeWorld Staff Writer A ngelina Jolie recently made headline news with her decision to undergo preventative mastectomies because of a strong family history and the revelation that she tested positive for a mutation of the BRCA1 gene. Genetic tests are becoming more common in all fields, including ophthalmology. Several companies now offer genetic testing for age-related macular degeneration. Although there are limitations to what information the genetic tests may offer, the ability to test for a genetic predisposition or to calculate the risks of developing wet AMD may offer some peace of mind to certain patients. EyeWorld interviewed Nancy Holekamp, MD, and Michael Gorin, MD, about advantages and disadvantages of AMD testing. Bonnie An Henderson, MD, cataract editor G enetic testing could offer a possibility for determining if a person is particularly at risk for developing age-related macular degeneration. These types of tests could be particularly valuable for those with a family history of AMD or those looking to undergo procedures where developing AMD would have a negative impact on results and future treatment. For example, cataract surgeons may want some indicator if a patient will develop AMD when considering a multifocal IOL or deciding what type of treatment a patient should pursue. While there are advantages, there are also negatives to consider before immediately assuming that every patient should have genetic testing for AMD. Current tests for this have limitations on accuracy and effectiveness, and since it is not certain that everyone with a family history of AMD will automatically develop the disease, tests should mainly be reserved for those already showing some degree of AMD. Nancy Holekamp, MD, director of retinal services, Pepose Vision Institute, Chesterfield, Mo., and professor of clinical ophthalmology, Washington University School of Medicine, Saint Louis; and Michael B. Gorin, MD, PhD, Harold and Pauline Price professor of ophthalmology, and chief of the retinal disorders and ophthalmic genetics division, Jules Stein Eye Institute, Los Angeles, weighed in on the topic, discussing two big tests right now, factors in determining how helpful the tests are, and potential disadvantages of AMD genetic testing. AMD genetic tests available Dr. Holekamp said there are currently two AMD genetic testing companies that have products commercially available—the Macula Risk test (ArcticDx, Bonita Springs, Fla.) and the RetnaGene test (Sequenom Center for Molecular Medicine, San Diego). "Each test is looking at 12-15 variations in DNA that, along with smoking history and the degree of AMD already present in a patient's eye, can help predict the risk of progressing to advanced disease," Dr. Holekamp said. "The DNA variations each company chose to look at are slightly different with the exception that both look at DNA variations in complement factor H and ARMS2." Dr. Holekamp said there is no specific indicator to determine how accurate these tests are, and instead of being FDA regulated, genetic tests are laboratory-developed tests (LDTs). "No licensing agency or regulatory agency mandates that the companies provide evidence of accuracy," she said. However, Dr. Holekamp noted that ArcticDx has published an algorithm of the first and second generation Macula Risk test, while Sequenom has performed a validation study for the first and second generation RetnaGene tests. Though AMD genetic tests are a promising option, Dr. Holekamp said they should mainly be reserved for those who already manifest some degree of AMD on a dilated retinal exam. "We now know that genetics account for about 65% of the risk of developing AMD," she said. "However, we also realize that not everyone with a genetic predisposition goes on to have the disease." According to Dr. Gorin, of the AMD genetic tests available, most provide selective testing of one or a subset of the genes related to AMD. "The tests fall into several groups," he said. There are those that look at targeted variants in one or more specific genes, those that do sequencing of specific genes, some that look at insertions and/or deletions in a