Researchers find 2 more genetic risk factors for Alzheimer...( St. Louis Sept. 6 2009 An internat...)

St. Louis, Sept. 6, 2009 An international team of scientists has identified two more genetic risk factors for Alzheimer's disease. The findings are reported in the online edition of the journal Nature Genetics.

The group, led by investigators from the School of Medicine at Cardiff in the United Kingdom and including scientists from Washington University School of Medicine in St. Louis, completed the largest genome-wide association study ever involving patients with Alzheimer's disease. The study pooled DNA samples from more than 19,000 older European and U.S. residents. Seven thousand had Alzheimer's disease, and the others had no clinical symptoms of the disorder.

Prior to this study, only four genes had been definitively associated with Alzheimer's disease. Three genetic mutations have been identified as causes of rare, inherited forms of early-onset Alzheimer's. The fourth gene, APOE4, is the only one previously linked to the more common late-onset form of the disease.

By looking at more than 600,000 common DNA markers, researchers on the current study were able to identify two new genes that appeared to be involved in elevated risk for Alzheimer's and confirmed the importance of APOE4.

"There's good evidence that these new genes may be novel risk factors, the first discovered since APOE in 1993," says Washington University researcher and co-author Alison M. Goate, D.Phil. "So it's a very important observation because this study is the first to provide such significant evidence of novel genetic risk factors for the most common form of Alzheimer's disease."

Goate, who in 1991 led a team in England that identified the first early-onset Alzheimer's mutation in the APP gene on chromosome 21, is now the Samuel and Mae S. Ludwig Professor of Genetics in Psychiatry and professor of neurology at Washington University. She says the new genes identified in this study are APOJ, also called clustrin on chromosome 8, and PICALM on chro
'/>"/>