A Genetic Variant Protective Against Alzheimer’s

alzheimers brain

Editor’s note: Pending an FDA decision, 23andMe no longer offers new customers access to health reports referred to in this post. Customers who purchased prior to November 22, 2013 will still be able to see their health reports, but those who purchased after that time will not. Those customers will have access to ancestry information as well as access to their uninterpreted raw data.

This past summer researchers announced they’d discovered a rare genetic variant that may be protective against Alzheimer’s disease. Alzheimer’s is an important topic among 23andMe customers so naturally they asked for more information about the variant.

After a review of the research,  we recently released a new Preliminary Research report on Alzheimer’s that covers this rare protective variant. The report is considered preliminary because the finding still needs to be confirmed by the broader scientific community. While our report is preliminary and only a very small number of people have this protective variant, the research is interesting nonetheless because of what it may say about the disease.

The variant is not found in the APOE gene, which is the most well-established genetic risk factor for the disease.Rather, the variant is located in a gene called APP. Rare mutations in APP are known to cause familial and early-onset forms of Alzheimer’s, but this particular variant is associated with lower risk for the disease. The study was done on more than  3,000 people with Alzheimer’s disease and about 9,000 people over the age of 85 without the disease. All of the participants were from Iceland. The results showed that the T version of  — also known as the A673T variant in the APP gene — was associated with about five times lower odds of Alzheimer’s.

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This is a very rare variant with only one person in 10,000 of European descent having the variant. But the finding is very intriguing to researchers and drug-makers. The disease-causing mutations in the APP gene lead to an overproduction of beta amyloid protein in the brain, a hallmark of Alzheimer’s. The protective variant appears to do the opposite, according to the study. New drugs built on this finding could help protect against Alzheimer’s, or even the mental ravages of normal aging.

Previous posts related to Alzheimer’s disease:
World Alzheimer’s Day
Genetics and the Risks from Traumatic Brain Injuries
SNPWatch: Do These Genes Make My Brain Look Big?
23andMe Launches Health Report on Alzheimer’s Disease
Studies Identify Five More Genetic Variants Associated with Alzheimer’s