In-office DNA test detects relative risk of progressive AMD

Optometrists are using the test results to counsel their patients on prevention.

Practitioners can now more accurately gauge the chances of a patient developing wet age-related macular degeneration with the use of a simple, in-office cheek swab and subsequent laboratory testing of genetic factors.

Macula Risk, which is manufactured by ArcticDx Inc. and distributed by Eye Solutions, can be administered in the optometric office to those patients who exhibit either drusen or early-stage AMD.

“Macula Risk is like having a crystal ball. We can gaze into a patient’s possible future by knowing their risk of developing advanced disease,” Gary L. Morgan, OD, a private practitioner from Peoria, Ariz., told Primary Care Optometry News. “If someone is in a high-risk category, we will follow them more frequently, allowing earlier intervention should they develop wet AMD.”

“We can now offer our patients a test with a very high degree of specificity, which is currently 83%,” David W. Nelson, OD, MBA, of Madison, Wis., told PCON. “This is a higher specificity than any genetic test in medicine for any disease.

“Approximately 20% of the Caucasian population has a genetic predisposition for macular degeneration,” Dr. Nelson continued. “For those with an early sign of the disease, there is about a one-third chance of having an average, above average or high risk of developing advanced AMD.”

Administering the test

At Dr. Morgan’s practice, the cheek swab is administered by a technician. Patients then typically return to the office about 1 month later for a follow-up exam. “It takes 2 to 3 weeks to receive the results back from the lab,” he said.

Macula Risk: The inner cheek on each side of the mouth is swabbed multiple times to increase yield, with a different swab used for each side of the mouth. After taking the sample from the patient’s cheek, the swab should be waved in the air to dry for 10 seconds and then placed back in its original package for shipment to the lab. Images: ArcticDx

Dr. Nelson’s patients perform the cheek swab in front of him, which takes slightly less than 1 minute. By the time he receives the results, patients have already had nutritional counseling and have undergone fundus photography.

The test is administered once or twice a day in his practice.

At the practice of Jeffry D. Gerson, OD, FAAO, in Shawnee, Kan., patients also swab their own cheek, “so there is no chance of any of our skin particles or DNA ending up on the actual swab,” he said in an interview.

The inner cheek on each side of the mouth is swabbed up and down multiple times to increase yield, with a different swab used for each side of the mouth, he said.

Dr. Morgan noted that both cheeks are swabbed as a precaution, ensuring that a second sample is available in case the lab is unable to collect from the first swab.

About 30 of Dr. Gerson’s patients have had the test over the past 9 months.

“To date, I have not had a single patient say ‘no’ to the test,” he said.

Test results, follow-up

Results of the test separate patients into one of five categories, MR1 through MR5.

“Categories 1 and 2 encompass 80% of patients with AMD, for which they have a 10% chance or less risk of developing wet AMD,” Dr. Morgan said.

In contrast, category 3 comprises 16.5% of patients (25% chance of developing wet AMD), category 4 is 2.5% of patients (45% risk) and category 5 is only about 1% of patients (but 65% risk), he said.

Those with a low-category risk “are obviously very relieved, while for those with a higher level of risk I can explain the meaning,” Dr. Gerson said. “It does not mean these higher-risk patients will necessarily develop AMD or a more progressive form; it means they just have higher odds of vision loss from AMD. We can discuss ways to become more proactive in monitoring their disease.”

Dr. Morgan said that during his follow-up exam, risks are explained and perhaps a baseline photo is taken or ocular coherence tomography is performed.

“If a patient is in a low-risk category, we may continue to follow them on a yearly basis,” he said. “For category 3, we may see them twice a year, category 4 three times a year and category 5 every 3 months.”

In Dr. Nelson’s practice, low and below-average risk patients are seen at 6 months to 1 year, whereas higher-risk patients are brought back immediately for a baseline OCT or microperimetry and a threshold visual field.

Patient feedback

Overall, “patients are enthusiastic about the test,” Dr. Morgan said. “If they have family members who have lost vision, it is very reassuring to them. And currently Medicare and most commercial insurances cover the test 100%.”

Dr. Nelson said Macula Risk is an easy process for patients and that acceptance is high after he informs select patients at the end of their exam that he has detected either drusen or early-stage AMD.

Providing Macula Risk “identifies us as a cutting-edge practice in our field of optometry,” he said. “This stimulates referrals of other patients.”

Dr. Gerson said that a test is not worth doing “if it doesn’t have the potential to alter therapy. For me, this test has the potential to alter the treatments I prescribe.”

For instance, Dr. Gerson thought a number of patients had fairly mild findings before taking the genetic test, only to discover afterwards that the genetic markers indicated these patients were at high risk for progressive AMD.

“I see these patients more often and I am more adamant about them incorporating the right types of supplements or diet or other lifestyle modifications,” Dr. Gerson said.

Greg Hines, president and chief executive officer of ArcticDx, in Toronto, Ontario, told PCON, “Since November, more than 1,000 eye care professionals have used our technology. The lab test is also covered by virtually all private and public insurers.”

The genetic prognostic test first became available in the U.S. to a small group of retina specialists in April 2009, followed by a broader roll-out in November 2010. The test analyzes at least four genes – CFH factor, ARMS2 factor, C3 factor and mt factor – that are associated with the progression of AMD, plus the smoking factor (never, ex-smoker, current smoker). Because a person’s genetic make-up does not change over time, the test is administered only once in a lifetime, he said.

The company has contracted with a laboratory in Denver to process results.

Effect on patient management

Mr. Hines believes that Macula Risk will make “a huge difference in how macular degeneration is managed. The disease is the biggest cause of vision loss in Caucasians older than 50 in the Western world. I think our test could be the center of a disease-management program for macular degeneration,” he said.

He added that genetic testing over the next 4 to 5 years should allow practitioners to better target drug therapy for AMD. — Bob Kronemyer

• Jeffry D. Gerson, OD, FAAO, can be reached at 16202 Midland Dr., Shawnee, KS 66217; (913) 962-2010; jgerson@hotmail.com.
• Greg Hines is president and CEO of ArcticDx Inc. He can be reached at Suite 200, 101 College St., Toronto, Ontario M5G 1L7; greg.hines@arcticdx.com.
• Gary L. Morgan, OD, can be reached at 18431 N. 91 Ave., Peoria, AZ 85382; (623) 933-6586; glmod@cox.net.
• David W. Nelson, OD, MBA, can be reached at 7428 Mineral Point Road, Madison, WI 53717; (608) 365-9591; amoptbddwn@aol.com.
• Disclosures: Dr. Gerson has no direct financial interest in the products mentioned. He has been on the advisory board for ArcticDx. Dr. Morgan has no direct financial interest in the products mentioned. He is on the Eye Solutions Advisory Board. Dr. Nelson is senior vice president of professional relations of Eye Solutions and chair of the Macula Risk/Eye Solutions Optometry Advisory Board. He is a paid consultant for Eye Solutions.