A new analysis revealed three new genes associated with the development of the disease previously unknown to Alzheimer’s researchers along with the confirmation of 20 other related genes.
For the last 25 years, the ApoE4 gene, which is a variant of a gene involved in the transportation of cholesterol, has been considered the risk factor most associated with Alzheimer’s after age itself. But scientists are uncovering data that shows we might not fully understand the big picture of how genetics plays into Alzheimer’s risk yet.
“This continuing collaborative research into the genetic underpinnings of Alzheimer’s is allowing us to dig deeper into the complexities of this devastating disease,” said Richard J. Hodes, M.D., director of the National Institute on Aging. “The size of this study provides additional clarity on the genes to prioritize as we continue to better understand and target ways to treat and prevent Alzheimer’s.”
Researchers led by the University of Miami’s Hussman Institute for Human Genomics and members of the International Genomic Alzheimer’s Project (IGAP) analyzed data from 94,437 people with Alzheimer’s disease in the United States and Europe.
Identifying common genetic threads among people with Alzheimer’s helps scientists figure out what might cause the onset and progression of Alzheimer’s. The newly discovered genes—known as IQCK, ADAMTS1 WWOX, along with a previously discovered ADAM10 and ACE—will need to be studied so scientists can see how they function in conjunction with the other common gene variations that showed up in the Alzheimer’s patients. So far, the data support the idea that groups of genes that control specific bodily functions—cell trafficking, lipid transport, inflammation and the immune response—are what researchers consider “genetic hubs” that may be behind the development of the disease.
The study also found that gene variants that have to do with amyloid precursor protein (APP) metabolism and beta-amyloid processing are present in both early and late-onset Alzheimer’s. That means that a therapy to treat one group could also treat the other.
This is the second study published by the IGAP. The first was published in 2013 and used data from over 75,000 people to identify 11 gene “loci” or locations, that previously were not associated with Alzheimer’s.
While the information won’t change the course of disease for current Alzheimer’s patients, it does give scientists another piece of the puzzle to answer why some people get Alzheimer’s and others do not. A large sample size helps scientists put the pieces together.
“Having more and more samples in [genome-wide association studies] data sets is like adding more and more pixels to a photograph—it helps researchers see details that they otherwise wouldn’t and helps them decide where to focus further study,” explained Marilyn Miller, Ph.D., director of the Genetics of Alzheimer’s Disease program in the Division of Neuroscience at N.I.A. “If the genes only appear in one out of ten thousand people, you need to find several samples containing those genes for results to be statistically significant.”