Kellogg Geneticist Works to Decode Riddle of Macular Degeneration

Radha Ayyagari Photo: Gregory Fox

Macular degeneration is a slow, relentless deterioration of central vision that cannot be corrected with glasses or surgery. Thirteen million people in the U.S. alone now suffer from some form of the disease, a number that will increase to 45 million by 2030. With no cure currently available, scientists are looking to genetic research for answers.

Kellogg Eye Center faculty member Radha Ayyagari, Ph.D., has been studying families in which members of all ages, from teenagers to the elderly, experience vision loss. “Macular degeneration is one of the leading causes of blindness in the world,” she says, “and with an aging population, we will see more of this disease in the years ahead.”

Macular degeneration is a complex inherited disease whose many forms have puzzled researchers for decades. Although most people begin to suffer the effects of macular degeneration only after the age of 60, some begin to lose vision much earlier. “One person in a family will get the disease in his or her 20s, while a sibling won’t be affected until age 50 or older,” Ayyagari says. Macular degeneration is considered a multi-factorial disease because the environment, diet, or some other external factor may combine with one or even many genetic defects to produce the disease.

Ayyagari hopes to clarify the role of genetics in the disease by studying large four- and five-generation families who suffer from “early-onset” macular degeneration. By selecting patients who begin to lose central vision in their early 40s, as compared to the typical onset at age 60, she can collect more — and more varied — information about the progression of macular degeneration. The ultimate goal of Ayyagari’s research is to develop treatments that will delay the onset, slow the progression, or prevent the disease altogether. After identifying the gene or genes that cause macular degeneration, Ayyagari will eventually be able to develop a test to help diagnose individuals at risk for the disease.

She is particularly interested in why members of a single family are affected at varying ages — or not at all — and uses a multi-generational chart or “pedigree” to give her a picture. “A genetic defect obviously exists,” she explains, “but something is protecting certain family members from the disease. If you can identify what stimulates the good gene, you can protect other family members.” By studying the disease across generations, Ayyagari hopes to get at the cause — and some day the cure — for macular degeneration.

—Randall Wallach