I might be better off NOT knowing some things about my genes.

Last blog I talked about how I was able to wrest information about my APOE gene from my 23andMe data. I wanted to know because of this gene’s link to late onset Alzheimer’s disease.

APOE comes in three versions: e2, e3, and e4. People with two e4 versions are around 15 times more likely to end up with Alzheimer’s than are people with two e3 versions. And if these e4 folks do get the disease, it tends to come at an earlier age.

I found out that I actually have two e2 versions which protects me somewhat from getting late onset Alzheimer’s. Good news? I guess…

In all of this, I didn’t ask whether this information is worth knowing. Being e2/e2 doesn’t mean I won’t get Alzheimer’s…it just means I am at a lower risk. But at least I didn’t find out I was e4/e4. Then I’d know I was more likely to get Alzheimer’s but not be able to do anything medically useful with that information.

Being e4/e4 would not have meant that I would for sure end up with Alzheimer’s. So it wouldn’t be like having two copies of the delta-508 marker of the CFTR gene. In that case, I would almost certainly have developed cystic fibrosis. No, two copies of e4 would just mean that I was at a higher risk.

And knowing this wouldn’t be able to help me medically at all. There aren’t any good preventative measures I could take to stave off Alzheimer’s.

Now this isn’t always true with these kinds of increased risk genetic markers—some are definitely worth knowing. Women who have certain BRCA1/BRCA2 markers are at an increased risk for getting breast or ovarian cancer. They can choose to screen early (and often) in the hope of catching the cancer early when it is more treatable. Or, more drastically, they can choose to have their breasts and/or ovaries removed. Neither is really an option for Alzheimer’s.

So knowing my APOE status isn’t really that useful medically (at least not yet). I can’t do anything useful with the information other than wait and see if I end up with Alzheimer’s. Which is pretty much what I would have done without the test.

I’m bringing all of this up because 23andMe is now offering people their APOE information (with an upgrade to their new chip, of course). People can now find out their particular combination of e2, e3, and e4 markers*.

In the past, the question was whether or not direct to consumer (DTC) genetic testing companies should offer such a test. That ship has either sailed or is getting ready to leave the harbor. The test will be made available to people who really want the information.

So now the key question is whether knowing your APOE status is worth it. The answer to this question will be different for different people. Given this, the most important thing is for people to have the information they need to make the right choice about whether they want to know their APOE status or not.

One way to figure this out is with a genetic counselor but most DTC tests don’t mandate that you need to talk to one before you are tested. This means it is absolutely critical that the online information provided by DTC companies are presented in an easy to understand way that does not oversell the genetic test. The DTC companies need to be upfront in the fact that this test is not predictive and that there are no proven preventative measures that can keep Alzheimer’s at bay.

I’ll let you all judge how well 23andMe has done at letting people know about what you can learn from the APOE test and what you can do with that knowledge. Click here to read what they have to say.

* You have always been able to get your APOE status with a more expensive genetic test from deCODEme.

Learn more about how genes and the environment work together to cause Alzheimer’s.

I put this video in the last blog but it probably should have gone in this one. It shows the unintended consequences of finding out you are e4/e4.

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Better Left Unknown? 25 April,2011Dr. Barry Starr


Dr. Barry Starr

Dr. Barry Starr (@geneticsboy) is a Geneticist-in-Residence at The Tech Museum of Innovation in San Jose, CA and runs their Stanford at The Tech program. The program is part of an ongoing collaboration between the Stanford Department of Genetics and The Tech Museum of Innovation. Together these two partners created the Genetics: Technology with a Twist exhibition.

You can also see additional posts by Barry at KQED Science, and read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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