February 12, 2007
Scientists have discovered a gene that may play an important role in the onset of Alzheimer's disease. The gene, called SORL1, was uncovered in a huge international study involving 6,000 people from varying ethnic groups. Dominican families that carry the gene are about three times more likely to develop Alzheimer's in old age than those who do not have the gene.
The gene adds to a growing list of dozens of genes that may play an important role in the onset of Alzheimer's disease. A handful of genes are known to cause early-onset Alzheimer's, which can strike someone in their 30s or 40s. Another gene, called APO-E4, has been linked to an increased risk of the more common late-onset form of Alzheimer's that strikes in old age, but just because someone carries this gene does not mean they will develop dementia.
More research is needed to confirm the role of SORL1 and its importance in Alzheimer's. Still, the findings could shed new light on possible new treatments for the illness.
In the current study, researchers at Columbia University isolated several genes that might be implicated in Alzheimer's. They then looked for this gene in various ethnic groups, including African-Americans, Dominicans, northern Europeans, and Israeli-Arabs. Only the SORL1 gene seemed to be linked to Alzheimer's.
Those who carry the gene produce excess amounts of a substance called amyloid precursor protein. This protein can then be converted into a toxic form of beta amyloid that clogs the brain and kills brain cells, leading to the symptoms of Alzheimer's over time.
With further research, scientists may be able to develop new drugs or other treatments that block this beta amyloid pathway. Still, much more study is needed before such treatments might be available.
Many factors, besides genes, play a role in the onset of Alzheimer's. To learn more visit www.ALZinfo.org.
E Rogaeva, et al: "The neuronal sortilin receptor SORL1 is genetically associated with Alzheimer's Disease." Nature Genetics (2006). DOI: 10.1038/ng1943.