Corporate Banner
Satellite Banner
Scientific Community
Become a Member | Sign in
Home>News>This Article

AD GWAS in African Americans Confirms, Reshuffles AlzGene List

Published: Thursday, April 11, 2013
Last Updated: Thursday, April 11, 2013
Bookmark and Share
African Americans carrying a variant in a cholesterol-processing gene have double the risk for Alzheimer’s than non-carriers.

This gene, for a membrane transporter protein called ABCA7, is the greatest difference between African American and Caucasian Alzheimer’s risk to emerge from the largest genomewide association study (GWAS) for AD performed in African Americans to date. The study appears April 10 in the Journal of the American Medical Association. In African Americans, ABCA7 variation is the strongest genetic risk factor for AD outside of the ApoE4 allele. Other than that, the genes involved in African American AD risk paralleled those in whites, reported the study authors representing the Alzheimer's Disease Genetics Consortium.

Led by senior author Richard Mayeux at Columbia University in New York City, the researchers examined single-nucleotide polymorphisms from nearly 2,000 people with late-onset Alzheimer’s, and almost 4,000 control participants. The group collected all the data it could get from African Americans seen at more than 20 study centers, said first author Christiane Reitz, also at Columbia.

While many of the previously reported GWAS data come from people of European and European American ancestry, Reitz noted that it is important to investigate whether those genetic findings extend to people beyond that white slice of humanity. A GWAS in Hispanics is ongoing.

Several of the genes the current study picked out in African Americans matched those found in GWAS with white people. ApoE4 was the strongest risk factor; a single copy more than doubled risk of Alzheimer’s with an odds ratio of 2.31 in this report. “Replicating an association for the same alleles in different ethnic groups strengthens the case for these variants being important in increasing disease susceptibility,” commented Robert Nussbaum of the University of California, San Francisco, in an editorial accompanying the publication.

After ApoE, ABCA7 was second on the hit list. ABCA7 variants had been reported to increase risk in white people, but ABCA7 was in the middle of the pack among genes linked to AD, most of which boost risk by an average of 10-20 percent, Reitz said (Hollingworth et al., 2011). ABCA7 currently ranks fourth on the AlzGene Top 10. In the new study’s African American population, an ABCA7 variant increased one’s chances of AD by almost double, with an odds ratio of 1.79.

This kind of race-based difference is not uncommon, Reitz noted. She suspects that the ABCA7 polymorphisms found in Caucasians point to specific functional mutations different from those carried by African Americans, but the researchers have not yet sequenced the gene to check. It is also possible that the genetic background of each race, as well as environmental factors, conspire with ABCA7 variants to produce a higher risk in African American carriers than in whites.

It is too early to think about genetic testing or ABCA7-based therapies, Reitz said. For now, researchers have to confirm the disease association in an independent population and study the biological function of the gene. That is no small task. ABCA7’s functions fit with the AD literature in that lipid dysregulation and cardiovascular disease are known risk factors (Breteler, 2000; Shepardson et al., 2011). ABCA7 encodes an ATP-binding transporter that participates in lipoprotein biogenesis, and secretion of phospholipids and cholesterol (Tanaka et al., 2011). It also influences the transport of amyloid precursor protein across the plasma membrane (Chan et al., 2008). “There are multiple ways in which ABCA might affect risk of late-onset Alzheimer's disease,” the study authors wrote.

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

AD GWAS in African Americans Confirms, Reshuffles AlzGene List
African Americans carrying a variant in a cholesterol-processing gene have double the risk for Alzheimer’s than non-carriers.
Monday, April 15, 2013
Scientific News
Exploring the Causes of Cancer
Queen's research to understand the regulation of a cell surface protein involved in cancer.
Ancient Viral Molecules Essential for Human Development
Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.
Tardigrade's Are DNA Master Thieves
Tardigrades, nearly microscopic animals that can survive the harshest of environments, including outer space, hold the record for the animal that has the most foreign DNA.
The Secret Behind the Power of Bacterial Sex
Migration between different communities of bacteria is the key to the type of gene transfer that can lead to the spread of traits such as antibiotic resistance, according to researchers at Oxford University.
Farming’s in Their DNA
Ancient genomes reveal natural selection in action.
GMO Food Animals Should be Judged by Product, Not Process
In a world with a burgeoning demand for meat, milk and eggs, regulatory policies around the use of biotechnologies in agriculture need to be based on the safety and attributes of those foods rather than on the methods used to produce them, says a UC Davis animal scientist.
Enzyme Critical to Maintaining Telomere Length Discovered
New method expected to speed understanding of short telomere diseases and cancer.
Gene Drive Reversibility Introduces New Layer of Biosafety
Ability to introduce or reverse the spread of genetic traits through populations could one day improve pest management and disease control.
RNA-Based Drugs Give More Control Over Gene Editing
CRISPR/Cas9 gene editing technique can be transiently activated and inactivated using RNA-based drugs, giving researchers more precise control in correcting and inactivating genes.
University of Glasgow Researchers Make An Impact in 60 Seconds
Early-career researchers were invited to submit an engaging, dynamic and compelling 60 second video illuminating an aspect of their research.
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos