Genetic Risk Factors For Age-Related Macular Degeneration May Be In Focus For Researchers

A report in Nature Genetics states a collaboration of international researchers have identified seven new genetic factors associated with age-related macular degeneration (AMD). This discovery may reveal new biological and therapeutic target treatments aimed at preventing or eliminating the condition.

The AMD Gene Consortium, a network of 18 research groups supported by the National Eye Institute, confirmed 12 genetic loci identified in previous studies. The study represents the most comprehensive genome-wide analysis of genetic variations associated with age-related macular degeneration.

The researchers examined genetic data from more than 17,000 patients with advanced AMD and more than 60,000 people without AMD. The loci they identified include genes involved in immune system signaling, lipid metabolism, remodeling of the matrix that surrounds cells, and blood vessel development. The researchers are continuing to study the genetic regions.

Jonathan Haines — lead author, principle investigator, and director of the Vanderbilt Center for Human Genetics Research — said:

“The consortium’s efforts have now explained up to 65 percent of the genetics of AMD … We’re getting closer and closer to understanding the full list of risk factors for AMD.”

Age-related macular degeneration is a common progressive neurodegenerative disease which causes vision loss in older individuals over the age of 50 in one or both eyes.

Despite the limited vision, AMD does not cause complete blindness. Peripheral, side-vision is still retained.

The condition gradually kills photoreceptor cells inside the macula, the part of the eye that provides sharp, central vision needed for seeing objects clearly.

The macula is made up of millions of light-sensing cells and is the most sensitive part of the retina, located at the back of the eye. The retina quickly converts light into electrical signals and then transmits them to the brain through the optic nerve. The brain translates the electrical signals into images we see. If the macula is damaged it can cause difficulty in recognizing faces, driving a car, and reading as fine-tuned focus is lost.

AMD progresses gradually over a prolonged period, but some can experience an increased onset of degeneration.

About 2 million people in the United States have advanced AMD, according to the National Eye Institute. In addition to genetic causes such as race and heredity — which account for about half of all cases of AMD — risk factors include age, smoking, high blood pressure, obesity, and diet. Current treatments for AMD help stabilize the disease, but they do not reverse the course of cellular degradation.

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