Raising the retinal disease treatment bar with genetic testing

This article was reviewed by Karmen M. Trzupek, MS, CGC

Genetic testing is not only important, but according to the American Academy of Ophthalmology, it is appropriate for most patients with presumed genetically caused retinal degeneration. The availability of genetic testing for inherited retinal diseases (IRDs) has improved markedly over the past 5 years as a result of sponsored genetic testing, which has helped eliminate prohibitive costs and travel burdens for patients.

Panel-based testing is important for patients with IRDs, given the complexities of these conditions. Although a small number of inherited retinal conditions are caused by mutations in a single gene, the picture is not so clear cut in most cases, in which underlying mutations can be identified in any of a large number of genes. For the majority of patients, testing based on phenotype is no longer adequate, according to Karmen M. Trzupek, MS, CGC, the director of clinical trial services and ophthalmology genetics at InformedDNA in Redmond, Washington.

“Genetic testing helps not only to establish or clarify a clinical diagnosis but also to determine the most appropriate (genetic) inheritance in order to provide counseling to the family,” she said. “In retinitis pigmentosa especially, the disease can be recessively or dominantly inherited, X-linked, or mitochondrially inherited.”

In addition, genetic testing is important for surveillance and to rule syndromic disease in or out. It is especially crucial for children with Leber congenital amaurosis (LCA) because some patients have LCA and retinal disease, whereas others have a much more serious systemic condition, Trzupek explained.

Further, the testing is vital for identifying patients who may be candidates for clinical trials and therapies.

Challenges

Despite the obvious importance of genetic testing, barriers remain to having testing performed. The greatest of these is the prohibitive cost, which is not always covered by insurance. In addition, it takes considerable time for many patients to travel to an IRD center at an academic medical center to consult with an IRD specialist.

Because of these barriers, Trzupek pointed out that there has been an increase in sponsored genetic testing. One such effort, the Open Access Genetic Testing Program, was started by Foundation Fighting Blindness, which offers genetic testing together with the company’s My Retina Tracker Program.

“This program has taught us a great deal. The most common reason that patients chose to participate in [it] was to determine their eligibility for participation in a clinical trial, which was expressed by almost 40% of patients. This is a significant change from the picture we saw a few years ago, and it continues to increase as a motivator for patients to be tested,” she commented.

Other motivators include the clarification of a personal diagnosis (33.5%), obtaining information about inheritance and risks to other family members (16.3%), and curiosity or contribution to research (10.9%).

Genetic testing also changed or confirmed an uncertain diagnosis in 12% of patients. Additionally, testing either changed a previously suspected inheritance or confirmed the inheritance type when it was previously unclear in almost 30% of patients, Trzupek reported.

When considering the genes associated with current gene-based clinical trials or therapies, she noted, this genetic testing program “is making a significant impact in identifying patients who might qualify for therapies. [This] is very important [regarding] our ability to enroll patients in trials and push forward the pace of clinical trial research.”

Impact on physicians

When the financial barriers to genetic testing were removed, retina specialists who referred patients to the program reported that the percentage of those who participated in relevant genetic testing increased from approximately 25% to over 98%.

The vast majority (over 90%) of 188 participating providers in the original My Retina Tracker genetic testing study chose to use telemedicine-based genetic counseling services, thus eliminating the travel burden for patients. More than 97% of patients expressed satisfaction with the counseling and testing they received.

“We were able to bring genetic testing to those clinics and patients who previously did not have access to those services,” Trzupek commented.

“In addition to IRD clinics that provide full services, patients also have the option of receiving services from optometrists or ophthalmologists in the community and retina specialists. [They can also] receive genetic counseling remotely through telemedicine services. The services currently available ensure that all patients can access genetic testing,” Trzupek concluded.