In this episode of Clinical Conversations in Retina, Daniel Epshtein, OD, FAAO, and Roya Attar, OD, MBA, DHA, FAAO, sit down to consider the uses and impacts of genetic testing for inherited retinal diseases (IRDs).
The threshold for ordering genetic testing
Dr. Attar describes genetic testing as a final step in diagnosing patients with inherited retinal conditions and considers it to be essential in caring for patients with IRDs. This form of genetic analysis can assist in establishing precise diagnoses when evaluating variations in clinical presentations, age of onset, and disease progression.
Further, testing can establish risk for family members and possibly identify exact genetic mutations, which can create opportunities for targeted treatments. Genetic testing can be fairly easy to obtain nowadays, Dr. Epshtein adds, and acts as a “piece of the puzzle” in diagnosing patients.
Before any genetic testing is ordered, it is important first to undertake a comprehensive clinical examination, says Dr. Attar.
Genetic tracking resources
The results of genetic tests can lead patients to look into potential therapies of ongoing clinical trials. There are different programs providing genetic testing for IRDs, including the My Retina Tracker Program from Blueprint Genetics and the Invitae IRDs Panel.
My Retina Tracker Registry, supported by the non-profit Foundation Fighting Blindness, is another such tool that has created an IRD database using panel testing, which tracks changes in multiple genes at once. It is a free program for eyecare providers (ECPs) and patients and can connect patients to genetic counselors and researchers who are conducting new trials.
With Blueprint Genetics, a specimen kit is mailed to the doctor, where an intake form is completed prior to sending back the sample. The results are typically available after a few weeks to both patients and ECPs. Dr. Attar describes it as a “straightforward program” for eyecare providers to add as an offered resource.
Dr. Epshtein uses Invitae testing, which can be performed by retrieving oral samples either from saliva or buccal cheek swabs or blood work. For saliva and buccal tests, which tend to be easier to administer, it is important for ECPs to inform patients not to drink water, eat, or chew gum 30 minutes prior to the test.
The value of genetic clinics
Patients may also obtain more specific genetic testing. One way to do so is by visiting genetic clinics. Unlike the broad approach of panel testing, clinics can drill down and order testing for specific disease states.
Resources to offer patients with IRDs
A valuable step that ECPs can take would be to provide patients with resources within their area. Dr. Attar recounts creating a list of low vision services and other resources to offer patients when she first moved to the Mississippi area.
Dr. Attar recommends Eyes on Genes as a resource for both patients with IRDs and ECPs treating them. The site provides a wealth of information and includes links to various organizations, such as the Foundation Fighting Blindness and Save Sight Now that patients can use to access local and national support or additional assistance.
Genetic testing results
There are three results that patients may receive from genetic testing:
- Positive: A disease-causing mutation that has been associated with a specific genetic condition has been identified.
- Unspecified: A mutation of uncertain significance has been identified.
- Negative: No significant mutation has been identified.
As companies conduct more research, the mutations of uncertain significance may later be revisited and reclassified. Considering panel testing may be run differently, and the database of mutations is increasing, it is usually recommended that genetic testing be performed every 2 years to collect more data to potentially classify unspecified mutations.
Genetic testing in age-related macular degeneration (AMD)
Of note, AMD genetic testing is not part of the preferred practice patterns laid out by either the American Academy of Ophthalmology (AAO) or the American Optometric Association (AOA). The development of AMD depends on a combination of genetic and environmental factors, meaning genetic testing alone will not determine if a patient will develop AMD.
With emergent technologies, Dr. Epshtein considers whether it might change how he manages his patients, including details such as their treatment or frequency of visits. Genetic testing in regards to AMD, such as Macula Risk from Arctic Medical Laboratories, provides interesting data but ultimately did not alter Dr. Epshtein’s management methods.
Dr. Attar and Dr. Epshtein have each noticed that patients who take the initiative to obtain a genetic test(s) and understand that they have an inherited risk of AMD often seem to be more invested in updating their lifestyle to prevent AMD.
This tends to push them to take more ownership of their overall health and heed the ECP’s advice to make healthy choices, such as refraining from smoking, using ultraviolet (UV) protection, or exercising regularly.
Monitoring patients at low risk for AMD
For younger patients who learn they may be at risk of developing AMD later in life, Dr. Epshtein usually performs a standard comprehensive eye exam, and the best recommendation he can offer them is to maintain a healthy lifestyle unless any specific disease is diagnosed.
Dr. Attar adds that she generally does not find it necessary to have more frequent eye examinations for patients under 50, as AMD is an age-related condition, and age is the biggest risk factor in its development. Finally, Dr. Attar mentioned that there are no recommended supplements or vitamins currently available specifically to prevent AMD.
Conclusion
Genetic testing can open the door to specialized and preventative care for patients with IRDs and those who might be at risk by aiding in identification and prognosis. Furthermore, they can connect patients to additional resources that may offer further support for their visual needs. It is of note that Janssen recently began offering no-cost genetic testing using Invitae.
While genetic evaluation and counseling may not make a significant difference in determining AMD, it can drive patients to be more proactive in caring for their overall health, considering the availability of over-the-counter genetic testing.
