April 4, 2011

New Alzheimer’s Gene Variants Discovered

Researchers have identified four more genetic triggers that lead to Alzheimer's, which is double the amount linked with the disease previously.

"This is a major advance in the field thanks to many scientists across the country working together over several years," Dr. David Bennett, director of the Rush Alzheimer's Disease Center, said in a statement. "These findings add key information needed to understand the causes of Alzheimer's disease and should help in discovering approaches to its treatment and prevention."

According to the scientists, if drugs or lifestyle changes could be devised to counter these genetic variations, over 60 percent of Alzheimer's cases could be prevented.

However, they said that those discoveries could be at least 15 years away.

Alzheimer's is the most common form of dementia that affects memory, thinking, behavior and the ability to handle daily activities.  The disease is increasingly placing a heavy burden on societies and economies across the world.

"We are beginning to piece together the jigsaw and gain new understanding," said Julie Williams from Cardiff University's center for neuropsychiatric genetics and genomics, who led the study.

"If we were able to remove the detrimental effects of these genes through treatments, we hope we can help reduce the proportion of people developing Alzheimer's in the long-term."

The researchers wrote in the journal Nature Genetics on Sunday that the genetic variants they found highlight specific differences in people who get Alzheimer's, including variations in the immune system, the ways the brain handles cholesterol and lipids as well as a process called endocytosis.

Alzheimer's Disease International said that as populations age, dementia cases will almost double every 20 years to about 66 million in 2030 and 115 million in 2050.

"What's exciting is the genes we now know of -- the five new ones, plus those previously identified -- are clustering in patterns," Williams said at a briefing in London.

Scientists say that genes can explain 60 to 80 percent of the risk of late onset Alzheimer's, which is the kind that occurs with age.

Williams and an international consortium of fellow researchers looked at data from 25,000 people with Alzheimer's disease and 45,000 healthy people who were used as "controls."

The team found that common gene variants known as ABCA7, EPHA1, CD33 and CD2AP and MS42A were linked with an increased risk of developing Alzheimer's.

"These five genes now show compelling evidence of association with Alzheimer's disease," she told Reuters.

Previous studies established that gene variants known as CLU, PICALM, CRI, BIN1 and APOE are also linked to Alzheimer's risk.

The Alzheimer's Disease Genetics Consortium conducted the new study.


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