Genetic Testing for Macular Degeneration
Reviewed by: HU Medical Review Board | January 2019 | Last updated: March 2019
Macular degeneration, especially age-related macular degneration (AMD), is a common condition that is one of the main causes of vision loss in people over the age of 50.1 In AMD, the macula is progressively damaged, which causes progressive central vision loss. In some people, the condition progresses slowly, while in others, the vision loss can be rapid. It can occur in one or both eyes, and you can have different stages of AMD in each eye. In its early stages, it is often asymptomatic, and is only detected by a comprehensive dilated eye exam.
What is genetic testing?
Genetic testing is becoming more and more popular, especially when it comes to certain medical conditions. Genetic testing is defined as “any clinical or laboratory investigation that provides information about the likelihood that an individual is affected with a heritable disease.”2 However, there are various risks and benefits to genetic testing, and the accuracy of genetic tests are not 100%. If someone is a carrier for a condition, that does not necessarily mean they will develop the condition, just that they may be more at-risk or may have a chance of passing the gene to their children.
Genetic testing for AMD
While genetic testing can be beneficial for some diseases by allowing for possible preventative therapies, encouraging increased surveillance for symptoms of the condition, and providing individuals with important information about their health in order to make informed medical and lifestyle decisions to benefit their health, there are some conditions in which genetic testing is not recommended, and AMD is one of these.
The American Academy of Ophthalmology (AAO) does not recommend genetic testing for AMD until specific treatment or surveillance strategies are developed. At least one published prospective clinical trial showed some benefit to patients with specific disease-associated genetic sequences.2 However, due to the limited amount of evidence and no established guidelines, more research needs to be done and experts currently only recommend genetic testing within the context of existing research studies. Put simply, until there are concrete tools and methods to help treat or monitor patients with AMD-associated genes, genetic testing for AMD has the potential to do more harm and create panic or stress rather than a positive influence on individuals and their health.
Genetic testing for Stargardt disease
In cases of Stargardt disease, genetic testing may be recommended, since findings would be “suggestive of a Mendelian disorder whose causative gene(s) have been identified.”2 This would also help to guide treatment, and perhaps allow the patient to take part in clinical trials and personalized treatments.
Understanding results of genetic testing
If you do get genetic testing, it is recommended that you do so under the guidance of a trained physician or genetic counselor – ideally, both – and not a direct-to-consumer test, which has gained popularity over the past decade due to increased advertising.2 A physician and genetic counselor can explain to you what the results mean, what risk factors really matter, and provide appropriate interpretations of the results and how they affect your life in a practical way, as well as what they could potentially mean in the future.
Aside from genetic testing, you can:
What can you do?
If you notice any changes in your vision at all, contact your eye doctor immediately. Macular degeneration is a progressive condition, so early identification from a regular screening exam is important. If you still want genetic testing, you should first discuss it with your eye doctor. They will be able to tell you the specific benefits and drawbacks of these tests pertaining to your personal situation and provide you with counseling tailored to your needs.