The findings, released April 4 by Nature Genetics, effectively double the number of genes known to contribute to the disease, according to Jonathan Haines, director of the Vanderbilt Center for Human Genetics Research and professor of molecular physiology and biophysics. Each gene individually adds to the risk of having this common form of dementia later in life.
“I’m very excited about this significant step forward in understanding why Alzheimer’s disease happens,” Haines says. “We’ve pulled together experts from all over the country and applied the power of modern genetics to identify these new genes.”
Risk for Alzheimer’s disease increases with age, with a prevalence of 3 percent to 5 percent for ages 65–69 and 30 percent to 40 percent in 85- to 89-year-olds. An estimated 3 million to 5 million people in the United States have the disease.
The study includes genetic analysis of more than 11,000 people with Alzheimer’s disease and a nearly equal number of elderly people who have no symptoms of dementia. Three other consortia contributed confirming data, bringing the total number of people analyzed to more than 54,000.
Investigators from 44 universities and research institutions in the United States were led by Gerard D. Schellenberg at Penn, Margaret A. Pericak-Vance at Miami, Lindsay A. Farrer at Boston, and Haines.
A fifth gene was identified by other groups of investigators from the United States, the United Kingdom, France and other European countries.
Until recently, only four genes associated with late-onset Alzheimer’s had been confirmed, with the gene for apolipoprotein E-e4 (APOE-e4) having the largest effect on risk. The Nature Genetics studies add another four—MS4A, CD2AP, CD33 and EPHA1—and contribute to identifying and confirming two other genes, BIN1 and ABCA7.
“Now we are working to understand why these genes are important,” says Haines. “And there are still more genes to find.”
© 2013 Vanderbilt University | Photography: DANIEL DUBOIS
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