A variant of a gene involved in cholesterol and lipid production is associated with significantly higher risk of late-onset Alzheimer’s disease in African Americans than in non-Hispanic whites of European ancestry, a recent study found. Although preliminary, the findings suggest that the two racial groups may have different genetic risk profiles for the most common form of Alzheimer’s dementia. The research is published in the April 10, 2013, issue of the Journal of the American Medical Association.
A person’s genes, along with age and environmental factors, are thought to play a role in the development of late-onset Alzheimer’s disease, which begins after age 60. Most previous studies of genes and Alzheimer’s disease have involved whites of European ancestry. However, studies on the rates of Alzheimer’s report that African Americans have a higher incidence of the disease than whites.
Led by Dr. Richard Mayeux, of Columbia University Medical Center, researchers analyzed genetic data for 5,896 African Americans age 60 and older, of whom 3,928 were cognitively normal and 1,968 had probable Alzheimer’s disease. The results showed that older African Americans had the same gene variants associated with Alzheimer’s as older whites but were also more likely to have a variant of the ABCA7 gene.
African Americans with the gene variant had almost double the risk of developing Alzheimer’s disease, compared with African Americans without the variant. The risk from the ABCA7 gene variant was as strong in African Americans as that from APOE ɛ4, the most important known genetic risk factor for late-onset Alzheimer’s in whites. This new discovery adds to our understanding of the cellular pathways involved in Alzheimer’s disease and may one day lead to promising targets for prevention and treatment, according to the study authors.
The research team conducted the analysis through a genome-wide association study, which rapidly scans complete sets of DNA of many people to find genetic markers associated with a particular disease. The NIA-supported Alzheimer’s Disease Genetics Consortium supplied the samples.
Reference: Reitz C, et al. Variants in the ATP-binding cassette transporter (ABCA7), apolipoprotein E ɛ4, and the risk of late-onset Alzheimer disease in African Americans. JAMA. 2013;309(14):1483-1492. doi:10.1001/jama.2013.2973.