In the past decade ophthalmologists gained a powerful tool to control vision-damaging "wet" age-related macular degeneration (wet AMD): anti-vascular endothelial growth factor (anti-VEGF) medications. Anti-VEGF drugs halt or even reverse damage in many wet AMD patients, but some do not respond as well to treatment and so suffer severe vision loss.
The new field of pharmacogenetics seeks to enable doctors to individualize treatment based on the patient's genetic profile for a disease. In a collaborative effort, the Hussman Institute for Human Genomics and Bascom Palmer Eye Institute at the University of Miami Miller School of Medicine studied whether specific genetic AMD risk factors and/or smoking influenced patients' responses to anti-VEGF treatment.
The researchers reviewed medical records of 36 people with wet AMD who participated in the Unifying Genetic Epidemiology of Macular Degeneration Study. In terms of anti-VEGF treatment, there were 12 responders whose vision improved, 18 maintainers, and 6 poor responders whose vision declined. All patients had been treated with bevacizumab (Avastin) and/or ranibizumab (Lucentis) for at least one year. None of the patients had vision loss due to cataract, geographic atrophy (advanced "dry" AMD), laser scar or retinal pigment epithelial tear. DNA analysis was done for two AMD-genetic risk factors: complement factor H (CFH) and age-related maculopathy susceptibility-2 (ARMS2) genes. Twenty-four patients had been smokers and three were current smokers. The average age was 80 years.
"Neither high risk genetic factors nor smoking history was significantly associated with patients' response to anti-VEGF therapy in our study," said Jaclyn L Kovach, MD. "However, more responders than poor responders carried at least one risk allele for ARMS2, CFH, or for both genes. Repeating this study in a larger population could bring us closer to a gene-guided therapy for wet AMD."
AMD is categorized as either "dry" or "wet." In the advanced "wet" form, abnormal new blood vessels develop under the retina that bleed or leak fluid and form scars. Advanced AMD destroys the detailed, central vision we need to recognize faces, read, drive, and enjoy daily life.This research was presented at the 2010 American Academy of Ophthalmology -- Middle East-Africa Council of Ophthalmology Joint Meeting. The AAO-MEACO meeting is in session Oct. 16-19 in Chicago.
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