Alzheimer's blog

A word of caution on genetic tests

By Angela Lunde March 12, 2008

You may be hearing that the first genetic test to be sold directly to consumers will become available this spring — a saliva test that can determine whether an individual has an increased risk for Alzheimer's.

A test of this nature may peak curiosity and interest for many of you; however, with a devastating disease like Alzheimer's our desire for answers is often a good news, bad news deal. There is no doubt that we want, and expect, the scientists to make progress in understanding the processes that cause Alzheimer's and other dementias.

Yet, these processes are complex and it is taking a great deal of time for the scientists to piece together the puzzle. As we wait, we may be inclined to use some of the pieces of the puzzle even when the picture is incomplete. So it is with some of the genetic information that has been gleaned over the past few years, especially regarding the apolipoprotein E gene (ApoE).

In general, researchers have identified an increased risk of developing Alzheimer's related to the apolipoprotein E gene found on chromosome 19. The ApoE gene comes in several different forms. The form or type we each carry influences our risk. However, there is no form that indicates Alzheimer's is certain. Some people carry the highest risk form and do not develop clinical signs of Alzheimer's, while others will.

So, having said all of this, one company is providing a test directly to the public that will provide their unique ApoE gene type. There are concerns with this. First, medical professionals believe that genetic testing should always be done as part of a process that also includes genetic counseling, which does not appear to be the case here.

Moreover, many people who don't carry the risky ApoE gene still develop Alzheimer's and conversely many people that carry one copy of it, don't get Alzheimer's. Bottom line, knowing your own gene type tells you nothing definitive about your risk of developing Alzheimer's. This is why the overwhelming consensus in the field has been not to offer ApoE genotyping to the general public. Yet people want answers and at least one company is prepared to capitalize on that.

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Mar. 12, 2008