Genetic Testing for AMD is here Today

by:Diana Shechtman OD FAAO & Steven Ferrucci OD FAAO

Age-Related macular degeneration (AMD) is a progressive disease and the leading cause of vision loss among the elderly, affecting central vision required for daily activities such as driving and reading. There are a number of factors affecting AMD, such as advanced age, smoking, UV exposure, overall health (that contribute to high blood pressure, obesity, diet) and family history. Many factors may be modified and yet others like genetics cannot. Although AMD may seem to be hereditary in some families and not others, genetics have been shown to contribute significantly to the disease. Multiple twin and sibling studies have collaborated to the familial nature of the disease. First-degree relatives of patients with AMD are at a significantly increased risk for the disease. Furthermore, large epidemiological studies have suggested a strong genetic risk factor for AMD. In fact, the risk of developing AMD increases 4 fold among patients with a positive family history. In 2005 a breakthrough occurred in the area of genetic research and AMD; Klein and associates discovered a strong link between AMD and certain genetic variants. Similarly, numerous other genes have been implicated in AMD, which may increase the risk of AMD up to 70%.
Until recently there was no test to help determined patient’s inherited risk for AMD. Today, Macula Risk (ArcticDX, Toronto, Ontario) is a genetic test specifically designed to determine genetic predisposition to AMD and vision loss attributed to the more advanced stage of the disease.
Macula Risk  genetic test separates individuals into one of 5 macula risk (MR) categories, with MR 3 through 5 representing an increased risk for the more advance stage of the disease. This accounts for approximately 20% of the general population. MR1 has less than a 5% risk of the advanced stage of the disease, while MR 5 carries greater than 55% risk. These results can aid the doctor in devising a specific management plan and follow-up protocol in order to reassure early intervention to prevent vision loss.
The test only requires a simple in-office cheek swab, which is sent directly to the genetic lab. The report includes test results and written genetic support information (including access to genetic counseling). Macula Risk genetic testing is covered by most insurance providers, including Medicare, as long as the specific diagnosis (ICD-9) are identified by the doctor. The prognostic genetic test is intended for patients who have a diagnosis of early or intermediate AMD. Thus, the “at risk patient,” would have to pay a fee for the test.
Despite our best efforts and new treatment options available today, many people are still losing vision from AMD. New advancements in the area of AMD are becoming an integral part in preventing future visual deterioration. AMD is affected by both environmental and genetic factors that interact with one another to determine prevalence and progression of the disease. Furthermore, at this time we do not know all of the genes linked to AMD. Hence, genetic testing in the area of AMD is only a risk indicator and cannot predict “without a shadow of a doubt,” which patients will and which will not develop the disease. However, this test provides a genetic profile screening to help identify those at risk as well as aids in tailoring a distinct management approach for those with the disease. With various researches devoted to treatment options for AMD, genetic testing in the area of AMD is at the frontier of providing crucial information.
REFERENCES
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