April 7, 2011

New Alzheimer’s genes identified

New Alzheimer’s genes identified

Vanderbilt investigators and colleagues from a consortium of research institutions have identified four new genes linked to Alzheimer's disease.

The findings, released this week in Nature Genetics, effectively double the number of genes known to contribute to the disease, according to Jonathan Haines, Ph.D., director of the Vanderbilt Center for Human Genetics Research.

Jonathan Haines, Ph.D.

Jonathan Haines, Ph.D.

Each gene individually adds to the risk of having this common form of dementia later in life.

“I'm very excited by this significant step forward in understanding why Alzheimer's disease happens,” Haines said. “We've pulled together experts from all over the country and applied the power of modern genetics to identify these new genes.”

“Now we are working to understand why these genes are important. And there are still more genes to find.”

Alzheimer's disease risk increases with age, with a prevalence of 3 percent to 5 percent for people age 65-69 and 30 percent to 40 percent for those age 85-89.

An estimated 3 million to 5 million people in the United States have the disease, costing $24.6 billion annually for health care and an additional $36.5 billion each year for lost productivity, worker absenteeism and replacement.

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.

A fifth gene was identified by other groups of investigators from the United States, the United Kingdom, France and other European countries.

Investigators from 44 universities and research institutions in the United States were led by Gerard Schellenberg, Ph.D., of the University of Pennsylvania School of Medicine; Margaret Pericak-Vance, Ph.D., of Miami Miller School of Medicine; Lindsay Farrer, Ph.D., of Boston University School of Medicine; and Haines.

“This is the culmination of years of work on Alzheimer's disease by a large number of scientists, yet it is just the beginning in defining how genes influence memory and intellectual function as we age,” Schellenberg said.

“We are all tremendously excited by our progress so far, but much remains to be done, both in understanding the genetics and in defining how these genes influence the disease process.”

Until recently, only four genes associated with late-onset Alzheimer's have 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.

The research was supported by the National Institute on Aging, National Alzheimer's Coordinating Center, NIA Genetics of Alzheimer's Disease Data Storage Site, NIA Late Onset Alzheimer's Disease Family Study and the National Cell Repository for Alzheimer's Disease.