Genetic Testing for Alzheimer's

Alzheimer's disease DNA testing and genetic counseling

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) With our growing and aging population, more people are becoming concerned about Alzheimer's disease. When is it appropriate to be tested, and how do people understand the results and risks?

Alzheimer's disease affects more than five million people in the U.S., and the numbers are growing along with our aging population.

More and more people are interested in genetic testing for the disease. To better determine their risk factor, new guidelines have been establish as a roadmap for early detection of this debilitating brain disorder.

"Ask your doctor about DNA testing for early-onset Alzheimer's."

With increased awareness of family history, the growing numbers of people affected by Alzheimer's and the availability of consumer testing, patient requests for information is increasing. Genetic testing is very complex, and most appropriate for families with a history of early-onset Alzheimer's.

There are three known genes related to causation of Alzheimer disease. When these genes mutate, they cause an individual to be at extremely high risk for the disease. A fourth gene indicates how susceptible a person is to early-onset Alzheimer's, which occurs in 1-5 percent of cases.

"Fewer than 2 percent of people with Alzheimer’s disease have an early-onset familial form of AD and carry a predictive gene that causes the disease," says Jill Goldman, MS, lead author of the guidelines.

"The siblings and children of these people have a 50 percent risk of inheriting the gene, and if they do, virtually a 100 percent chance of developing AD.

However, for the other 98 percent of people living with AD and for their relatives, there is no simple genetic test that can predict the future."

Recent years have seen direct-to-consumer genetic tests come on the market but the new guidelines, published in collaboration with the American College of Medical Genetics and the National Society of Genetic Counselors, stress the importance of counseling along with genetic testing. The guidelines also recommend a complete family history and risk assessment be completed.

Home testing is never recommended due to their poor predictive value, and counseling is essential due to the psychological impact.

The guidelines were published in the June 2011 issue of Genetics in Medicine, the official journal of the American College of Medical Genetics.

Reviewed by: 
Review Date: 
July 13, 2011
Last Updated:
July 18, 2011