Dear Jeanie: Can a Genetic Test Determine the Best Medications for My Son?

Editor’s note: The “Dear Jeanie” blog series uses fictional patient questions written by an NSGC expert based on her experiences as a genetic counselor. This series in no way represents a real patient or single genetic counseling session. 


Dear Jeanie,

My son (call him Ben) was a happy child, but as he got older he became anxious and withdrawn.  He had always loved school and now he didn’t want to go. He spent too much time alone in his room.  We took him to a psychiatrist who put him on an antidepressant, and for a little while it was like we had that happy boy back again. 

It got worse when Ben went off to college. For four years we’ve been stuck in a vicious cycle.  He’s less anxious when he comes home, but he feels like a failure and it makes him depressed.  He tries so hard to get back to school, but as soon as he falls behind he gets too anxious to go to class, and then the wheels fall off. 

Four years ago this seemed like a typical teenager problem that would go away, and now we are beginning to fear it will ruin his whole life. We want to try changing his medication but last time we did that it was a disaster, and he ended up in the hospital for a week.  A friend showed me an advertisement on line for a test that tells your doctor what medication to use based on his genes.  My son’s doctor says she doesn’t use those tests.  Ben is very fond of his doctor, but maybe we should find someone else. 

Is it time to find another doctor?

Sincerely,

An Anxious Mother


 

Dear Ben’s Mom,

I am so sorry.  Nothing could be worse than watching your child struggle, and being unable to help.  Depression is a thief, who steals from your son the life he should have had. 

It is easy to understand why you are frustrated.  People respond so differently to anti-depressants, and every drug has its side effects, some of them serious.  It makes sense to think that a genetic profile would be a better way to choose a treatment than trial-and-error.  The science of picking drugs based on genes is called pharmacogenetics, and it is the holy grail of many fields, but especially psychiatry.

I wish I could tell you that a genetic test is likely to help your son, but I can’t.  An effective test does not exist, at least not yet. We haven’t identified clear predictive relationships between genes and drug response.  I know that companies are marketing these tests, but so far there is no good evidence that they improve outcomes. 

Still, I can imagine you saying, isn’t it worth a try?  If what we are doing now isn’t working, what is the harm?  That’s a very reasonable question.  And maybe, except for the cost, there will be no harm.  But often a bad test is worse than no test at all.

Results from pharmacogenetic testing label certain medications as “recommended,” “not recommended” or “use with caution.”  Even a doctor who is skeptical about the value of testing is going to avoid prescribing a drug when there is a report in writing suggesting it could be dangerous.  But in fact, those labels are going to be wrong a significant percentage of the time – lots of our early assumptions are wrong – and when they are right, they may not be clinically significant.  Here’s an example of what I mean by “not clinically significant”: let’s say there is evidence that having a particular variant of a gene doubles the risk of a side effect.  That’s a huge increase!  That’s a 100 percent increase.  Given that giant increase, if the risk of that side effect in the general population is 1 percent, the adjusted risk is (drum roll please)… 2 percent.  Not exactly a game changer. 

I wish I could tell you that a genetic test is likely to help your son, but I can’t.  An effective test does not exist, at least not yet. We haven’t identified clear predictive relationships between genes and drug response.  

So a genetic test can have doctors avoiding drugs that might help, or push them to make changes in medication that aren’t likely to be effective.  As you have experienced, altering medications is a big deal, and has its own set of risks.  As much as it might feel like some advice is better than no advice, that isn’t necessarily true.  This is why steering people away from the wrong test is as much a part of the job for genetic counselors as steering people toward the right test.

But the worst thing about genetic testing in the situation you describe in your letter is that it might deprive you of something that has been demonstrated over and over to improve mental health outcomes: a stable, positive relationship with a doctor your son trusts.   If you don’t think the doctor is doing a good job, by all means get another opinion.  Otherwise, don’t underestimate the value of having a doctor who knows your son and his history.  Doctor-patient relationships are the original personalized medicine, and evidence suggests that this relationship along with the love and care and support of a concerned family provide Ben with the best chance of reclaiming his life.

Best wishes,

Jeanie

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