Article Date: 7/1/2011

Genetic Test Helps Determine Risk of AMD
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Genetic Test Helps Determine Risk of AMD

Samantha Stahl, Assistant Editor

The role of genetic risk assessment in clinical practice has begun to blossom, particularly for diseases where early detection is crucial.

Macula Risk, from Arctic Dx, is a prognostic genetic test for patients diagnosed with early or intermediate AMD. A cheek swab is performed in-office and sent to the lab, with results returned to a doctor in three to four weeks. Four different genes (CFH, ARMS2, C3 and mt factors) as well as smoking history are analyzed with a mathematical model. Patients are then placed into one of five different risk categories, ranging from low to very high odds of progressing to advanced AMD with vision loss. Currently, the test is offered as a Laboratory Developed Test under CLIA regulations.

MANAGING HIGH RISK

“The risk score allows me to customize the frequency of follow-up visits and testing to concentrate more resources on higher-risk patients,” says Carl Awh, MD, of Tennessee Retina, who finds the test particularly useful for older patients with moderate AMD and good vision. He presently orders about 10 tests per week, but is looking to modify his practice pattern as he gains more experience with the test.

He also finds the test useful for younger patients with mild disease and with a family history of advanced AMD, and dealing with “the anxiety that often accompanies such a family history.” Macula Risk, which is covered by Medicare and most private insurance companies, cannot predict whether a patient will develop advanced AMD, but it can play a vital role in determining a course of action in patients based upon calculated risk.

When a patient receives a high-risk assessment, Dr. Awh follows them more frequently and recommends AREDS supplements even if the patient's clinical findings may not meet the threshold identified by the clinical trial. He also recommends home vision monitoring with a potential hyperacuity perimetry device for high-risk older patients.

“Earlier detection leads to better outcomes in cases of neovascular AMD,” Dr. Awh says. “This test allows us to increase both patient and doctor awareness, although there is little to do to influence the course of the disease beyond the recognized benefits of nutritional supplements.”

CASE IN POINT

Peter Sonkin, MD, also in practice at Tennessee Retina, saw a 79-year-old white female who presented with visual acuity of 20/30 in both eyes and AREDS category 3 dry AMD in each eye. He performed the Macula Risk test, advised her to use an Amsler grid each day, prescribed an AREDS vitamin formulation and asked her to return in 12 months to follow up.

However, when her Macula Risk results returned with a category 3 risk score (indicating increased risk), the patient was advised to return for follow up in eight months rather than 12. At follow-up, her visual acuity was 20/40 in both eyes, fundus examination was stable and time domain OCT revealed a suspicion for a rare cyst in her right macula.

When she returned a week later for an exam, SD-OCT revealed mild, deep intraretinal and subretinal fluid in the right eye and fluorescein angiography found atrophic changes in both eyes with possible mild occult leakage in the nasal macula of the right eye. She then began monthly ranibizumab injections.

Dr. Sonkin credits Macula Risk for altering the management of this patient. By bringing her back into the office and using OCT sooner, he was able to detect conversion to neovascular AMD early and initiate ranibizumab injections before the development of symptoms or a significant drop in visual acuity, likely resulting in a better long-term outcome.

THE FUTURE OF GENETICS

“The era of genetic testing as an important component of the diagnosis and management of many diseases, including AMD, is here,” says Dr. Awh. He finds genetic assessment to be an invaluable tool for counseling and follow-up planning, and believes the benefit of genetics is only just beginning.

“I'm confident that preventive therapies will be developed for AMD, making genetic risk testing of even greater value as we learn more and can use the information to select and modify treatments,” he concludes.

For more information, visit www.macularisk.com.



Retinal Physician, Issue: July 2011