Researchers find two locations in the human genome that may harbor genes that increase the risk of Alzheimer’s disease

Researchers at Columbia University Medical Center have found two locations in the human genome that may harbor genes that increase the risk of Alzheimer’s disease. If confirmed, they will be the first genes linked to Alzheimer’s disease since ApoE4 was discovered in 1993.

The findings are published in the November issue of Molecular Psychiatry, a journal of the Nature Publishing Group.

“We feel confident that we may be closing in on new Alzheimer’s genes,” says the study’s senior author, Richard Mayeux, M.D., co-director of the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University Medical Center. “This is a major collection of families, and family studies really give you more confidence that the region you’re looking at is significant.”

Researchers think that Alzheimer’s is caused by the interaction of several different genes, but so far only one gene, ApoE4, has been linked conclusively to the disease. Finding the other genes will be a huge step toward understanding how Alzheimer’s begins and how it can be treated. It will also allow clinicians to predict who will develop Alzheimer’s later in life and who will benefit from drugs that prevent the disease.

The new study found strong evidence for new Alzheimer’s genes on chromosomes 18 and 10. The region on 18 had never been strongly linked to the disease before, while the link to chromosome 10 confirms previous findings by other Alzheimer’s researchers.

The evidence for both locations is relatively strong because the researchers used a large collection of 96 families with Alzheimer’s disease. A total of 490 parents, children and siblings were studied.

The researchers do not yet know which gene in the chromosome 18 region is responsible, but since the region is small, there are only a few possibilities. Dr. Mayeux and his colleagues are now trying to identify the gene.

The region on chromosome 10 had been linked to Alzheimer’s before, but only in studies of Caucasian families. The current study found the link in Caribbean Hispanic families, most of who live in the Dominican Republic.

“To find the same location in a different ethnic group strongly suggests that there’s a gene for Alzheimer’s in that region,” Dr. Mayeux says. “Human diseases should cause disease in every ethnic group.”