New Genetic Link for Alzheimer's Disease Found

July 31, 1995

Scientists at the University of Pittsburgh Medical Center (UPMC) Alzheimer's Disease Center have discovered that two forms of a gene for ACT, alpha1- antichymotrypsin, profoundly affect a person's risk of developing late-onset Alzheimer's disease (AD). The identification of this new risk factor supports the idea that the risk of being affected by AD is determined by the interaction of many genetic risk factors. The findings are published in the August issue of "Nature Genetics." The study was funded by the National Institute on Aging.

The Study

The investigators studied 225 people between ages 22 and 101, 109 of whom had AD confirmed by autopsy and 116 of whom were clinically assessed to have AD. Genetic findings of these individuals were compared with 315 individuals, ages 42 to 92, who did not have AD.

"We have described two forms of the gene for ACT," said M. Ilyas Kamboh, Ph.D., associate professor of human genetics at the UPMC and co-principal investigator of the study. "The first form of the ACT gene itself is associated with an increased risk for Alzheimer's disease and, in addition, dramatically intensifies the risk for those who also...

Intriguingly, the chromosome 1 gene bears a striking chemical resemblance (67 percent homology or similarity) to a different gene on chromosome 14 identified as influencing early onset Alzheimer's, but affecting a different set of families. This information gives researchers a significant boost in their understanding of how these genetic abnormalities may influence the development of Alzheimer's because of the similarities in the proteins produced by the genes.