Eyeworld

I SEPTEMBER 2020 | EYEWORLD | 33 by Ellen Stodola Editorial Co-Director how much it would cost to test family members who might be at risk. "We plan to do that moving forward to see if family mem- bers are at risk for a certain strain or gen- otype of keratoconus to know if we should crosslink early on instead of waiting to see if it appears in corneal topography or slit lamp," he said. Dr. Yeu added that keratoconus tends to progress most rapidly in patients aged 13–30, so it's advantageous to be able to identify and monitor them as early as possible. This is a nice technology for keratoconus, Dr. Trattler said, because it's a simple cheek swab that tests for a variety of genes associated with keratoconus. "Avellino evaluated patients with keratoco- nus and compared their genetic profile to con- trols without keratoconus. They also incorpo- rated known genes associated with keratoconus. The Avellino test evaluates more than 75 genes unique to patients who have keratoconus," he said. Based on these results, a scoring system was developed. The genes that were more com- mon had a higher score, the genes that were less common had a moderate score, and genes that were even less common had a lower score, Dr. Trattler said, explaining there is not one gene that identifies keratoconus. The big challenge, he said, is that just be- cause a patient has a gene doesn't mean that the patient will develop keratoconus. In addition, it's not known yet whether there are genes that predict for more rapid keratoconus progression. Additionally, someone without genetic evidence could also still develop keratoconus. "There's no hard rule," Dr. Trattler said. "But it's interesting to look at the role genes play in keratoconus, and as more data is collected, more will be learned." W hile there are many op- tions being explored in the field of genetic testing and gene therapy, one area of interest is genetic testing for keratoconus and other corneal dystrophies. Avellino has developed such genetic testing, including a new test to identify markers for ker- atoconus. Elizabeth Yeu, MD, William Trattler, MD, and Mitchell Jackson, MD, discussed this type of testing, how they are currently using it, and ways it might be applicable in the future. Avellino previously developed a genetic test for granular corneal dystrophy (also known as Avellino dystrophy) and further developed to test for several other mutations of the trans- forming growth factor beta induced (TGFBI) gene. The AvaGen test was released in late 2019, and according to Dr. Yeu, it looks for dozens of mutations of the TGFBI gene, as well as markers in other genes that are associated with keratoconus and other corneal dystrophies. When deciding the best candidates for this genetic testing, both Dr. Yeu and Dr. Jackson said they start with patients who are already diagnosed with the disease. Dr. Jackson noted that in patients already diagnosed with keratoconus, performing this genetic test can identify specific markers to then pinpoint if family members are also at risk. A positive genetic test in family members who are not already diagnosed with keratoconus can be incredibly helpful to monitor progression and earlier diagnosis of clinical findings. Before the current pandemic, he had been working on a plan to implement genetic testing for keratoconus in his practice. He noted that he is still working on adopting it and structuring Genetic testing for keratoconus continued on page 34 "As more patients have the tests and there's more data, we'll be able to learn more, and the test will be even better." —William Trattler, MD At a glance • Avellino has developed genetic testing to look for genetic markers for keratoconus as well as several other corneal dystrophies. • Currently the test is not covered by insurance, so patients pay out of pocket or the physician needs to cover the cost. • Physicians may want to use the test for a variety of patients including family members of patients with keratoconus or potential refractive surgery candidates.

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