Wednesday, September 10, 2014

The perils of genetic testing

Most people don't understand the consequences of genetic testing. You may think that you can handle all of the data and information but think again.

This is the story of someone who got their DNA tested by a commercial company and he persuaded his parents to participate as well. What could possibly go wrong? The title of the article tells the story: With genetic testing, I gave my parents the gift of divorce.

Turns out he has a half-brother! His father never mentioned that he had a son with another woman.
At first, I was thinking this is the coolest genetics story, my own personal genetics story. I wasn't particularly upset about it initially, until the rest of the family found out. Their reaction was different. Years of repressed memories and emotions uncorked and resulted in tumultuous times that have torn my nuclear family apart. My parents divorced. No one is talking to my dad. We're not anywhere close to being healed yet and I don't know how long it will take to put the pieces back together.
It's not always true that having information is better than not having information. If you beleive that then you are very naive.


49 comments :

  1. This has to be the stupidest argument against genetic testing I've heard of.

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    1. I can always count on you to overinterpret whatever I say.

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  2. You have to be careful. I have heard of a university lecturer explaining the inheritance of eye color as due to a simple recessive allele for blue eyes. So, he said, two blue eyed parents could not have a brown-eyed child. At which point a brown-eyed woman in the audience broke out crying. On further examination it proved that, actually, eye colors are more complicated than that, and that she was one of the exceptions. Of course it could just as easily have turned out that she was not the biological daughter of her father, but it happened in this case that she really was her father's daughter.

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    1. My post on the genetics of eye color is the second most popular post on Sandwalk. I get questions every week from people who are upset about the fact that their children or parents don't have the right eye color. I usually refer them to OMIN because it lists all the alleles and explains just about every possible anomaly.

      I strongly recommend that teachers avoid using the eye color of their students and parents in order to teach genetics. It's bound to get them into trouble.

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    2. @Joe Felsenstein

      I know of a similar college case as well.

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    3. I wish the people who write about Mendelian inheritance elementary textbooks would read your article (which I saw for the first time today and which I think is very good). There is far too much oversimplification implying (or even saying, in the worst cases) that brown and blue are the only possibilities. When I look at myself in the mirror the eyes that I see looking back at me are neither brown nor blue, and a great many other people can say the same. My wife's eyes are much the same colour as mine, but our daughter had dark brown eyes as a child, which have lightened over the years, so they are now just brown (and still quite different from ours).

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  3. If you cheat on your partner don't let them find out. It's better they not have that information. So says, Dr. Moran.

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    1. So you're advocating cheating with their full knowledge?

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    2. How about ... not cheating?

      I know it may sound crazy, but this seems to be the ethically defensible order of actions:
      1. Break up with current partner.
      2. Start relationship with new partner.

      Alternatively:
      1. Have an open relationship.

      Of course, in the latter case it would not be cheating, as such.

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    3. Ah, if only love were so simple and serial!

      Alternative W: "I've met someone else and I'm off". "You haven't started a relationship with them then?" "Er ... not yet, no. I've just ... met them. I thought I'd best break up with you first". "Ah, that's fine. On your way, then. You can have the Rush cds. Hurt? No, why would I be hurt?".

      Alternative X: "I'd like to meet someone else so I'm off". "No-one in particular in mind?" "No, I just think I'll meet someone I like more than you if I give it a go. Even if it means a hundred dates with people I don't even like". "Ah, that's fine. On your way, then. You can have the cat. Hurt? No, why would I be hurt?".

      Alternative Y: Stay miserable. Think about the kids, money, property, hurt, uncertainty, the judgement of society, the hopes and expectations of any prospective other partner ... love is for other people. Just Say No.

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  4. One of my psychiatric colleagues once told of a genetic study he was involved in that involved doing genetic testing of entire families. One of their unexpected findings was that, while the paternity of the first child was almost always the woman's husband, with the second child it went down to 80% and by the third child it was around 50%! (They did not divulge this information to the participants.)

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    1. That's implausible.

      I'd be willing to bet $1000 that it isn't true. (Unless the study deliberately choose families where the mother had multiple affairs.)

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    2. Well, that's how the story was told. He (or I) could have misremembered the figures, or it could just have been a quirk of the particular group of people they ended up recruiting. The broader point is that this is inevitably going to come up at least occasionally in genetic research or in clincial situationa, and investigators/clinicians should probably figure out beforehand how to handle the situation.

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    3. Physicians and genetic councilors have been trained to deal with issues of unexpected paternity. The problem has been around for over 30 years and it's standard stuff in any medical ethics course.

      The general public, on the other hand, is not trained to deal with such shocks.

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    4. BTW, I'm interested in critical thinking. When you think critically, are you still prepared to believe that 50% of all third children in a family are not the child of the husband?

      Don't you think somebody would have noticed?

      Typical rates for Non-patermity events are about 3%.

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    5. Possibly so, but the rate of non-paternity among people testing for paternity because they suspect non-paternity is much higher. This selective effect of who is signing up for testing could account for the higher rate than the non-selected rate.

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    6. To be clear, I was not suggesting that 50% of all third children are not the child of the husband. Just that that was what was found in one study reported to me verbally. No, I wouldn't expect that to be a general finding.

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    7. Typical rates for Non-patermity events are about 3%.

      It seems to depend a bit on the culture and social class though. I remember reading of a study done in a poor suburb of some European city where it was in the low double digits. If, in that case, most families still had less than three children the numbers given by lutesuite could work... but yeah, 50% for the third child seems a bit excessive.

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    8. In his book Adam's Curse Bryan Sykes got a lot of the statistical arguments wrong, but he offered one piece of empirical information that is relevant. He found that about half of the men in England with the names Sykes today have the same (or almost the same) Y chromosome, implying about 99% fidelity of transmission in each generation (assuming, as seems to be correct, that the name was only invented once). That's higher than I would have guessed, but anyway much higher than the claim about 50% of third children would indicate.

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  5. If ignorance is superior to knowledge as Dr. Moran suggests, perhaps the IDiots have us beat.

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    1. Hmmmm ... I never thought of that. Give me a day or two to try and figure out a way to avoid the obvious conclusion .....

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  6. Ignorance about what?

    An extreme example, but would you really want to know that tomorrow, you will die? I wouldn't but it would not be a surprise, happens all the time...

    Maybe we should have legislation against keeping family secrets secret?

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    1. Genetic genealogy testing is actually illegal in France. My guess is there are a lot of powerful legislators who don't want to pay for their "non-paternity events."

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  7. Then there's chimerism, which was in the news again last week.

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  8. When I saw the title I was expecting something very different - e.g. people making life-altering decisions (or freaking out, etc) based on finding out they have a gene which slightly increases the probability they'll get a disease (which is an issue). This is not what I was expecting.

    I also don't see it as a "problem" with genetic testing - there are any number of other routes that this information could have been "exposed" through; the identification of the half brother was not something solely enabled by genetic testing. Indeed, similar "issues" arose with the advent of blood typing, and yet we continue to do that routinely. There are many routes through which adopted children find birth families, etc. The unexpected discovery of half siblings, cheating spouses, etc, has been going on for as long as humans have existed; genetic testing (and in this case, the "exposure" of other peoples sequences for comparison) merely opened an additional door to something that is an old part of humanity.

    If anything, this is an argument for placing appropriate controls around the availability of sequence data, rather than an argument against sequencing itself. Had 21&Me not allowed for these sorts of comparisons, this story would have never happened - at least, not in its current form.

    I think its also worth pointing out the authors own words At first, I was thinking this is the coolest genetics story, my own personal genetics story. I wasn't particularly upset about it initially, until the rest of the family found out. For the author this started off as a positive experience; it wasn't the genetic testing that was the issue - nor its result - it was the resulting actions of his family. The testee was excited, until his family ruined it for him.

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    1. I don't have a problem with genetic testing as long as people realize that they could discover things they don't want to know. Before you submit your DNA should have to read and sign a short, easy to understand, warning about the potential perils. I doubt very much that the father in this family would have agreed if he had known what might happen.

      I'd also like to mention that the so-called benefits are vastly over-hyped and the errors in identifying medical issues are very much downplayed. There aren't very many situations where knowing the sequence of your genome is going to make a difference in your life. On the other hand, there are lots of situations where you can be worried and stressed about something over which you have no control. Do you really want to know that you have a 10% greater risk of developing Alzheimer's? Will that make you happier?

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    2. Before you submit your DNA should have to read and sign a short, easy to understand, warning about the potential perils.
      I believe that this is (was? - I think the FDA made them stop) the case for 23&me. According to the article, the author did have to opt-in (versus opt-out) for the family search feature, meaning he knowingly and deliberately chose to receive that data.

      There aren't very many situations where knowing the sequence of your genome is going to make a difference in your life
      Agreed - so long as you add the qualification of "today" to the beginning of the statement. Far more unknowns than knowns today - but that very likely will change.

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    3. As a former family counselor I have to say that the cause and effect is rather fuzzy here. Marriages that break up because some decades old sin is revealed are probably not the soundest.

      My other observation is that this kind of knowledge cannot be suppressed forever. Regardless of our wishes, the technology will get cheaper, and genealogy hunters will make links with or without the cooperation of everyone affected.

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    4. Larry: "I doubt very much that the father in this family would have agreed if he had known what might happen."

      But then he would have to explain to his family why he was refusing to have the DNA test.

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    5. In families I worked with, the knowledge or suspicion was already there. I think it was Dawkins who said that newborns resemble their fathers more than their mothers because there isn't much doubt about who is the mother.

      Children tend to resemble their parents temperamentally, also. That may not be politically correct (and it may not actually be true) but parents look for resemblances and subtly reject children who don't appear to fit).

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    6. Petruska says,

      Marriages that break up because some decades old sin is revealed are probably not the soundest.

      Are you married? If so, are you telling me that you wouldn't be upset to learn that your spouse had another child by a different man/woman while you were away for a year?

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    7. acartia,

      But then he would have to explain to his family why he was refusing to have the DNA test.

      You don't really think that's a problem, do you? I refuse to have my genome sequenced and I'm not hiding any secrets—at least not those kind of secrets.

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    8. Everybody knows you are trying to hide the secret that you don't have any junk DNA in your genome.

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    9. Why in the world would to refuse to have your genome sequenced? I seriously don't get it. Isn't it exciting to look at data that represents yourself? I've already looked at SNP data of myself and can't wait to get my hands on full sequence.

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    10. Oh, very mature there. Seriously, the idea of looking at your genome doesn't fascinate you? I know you, like me are mostly interested in microbes, but doesn't the fact that you can analyze yourself just like you can any other organism with a genomic sequence intrigue you in any way?

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    11. No, the idea of looking at my genome doe not fascinate me.

      I can't imagine how knowing all the mutations in my genome could possibly make me happier than I am now. On the other hand, I can imagine how it could make me less happy.

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    12. My deep heritage (anything before grandparents) is lost to me due to the Holocaust and the consequent destruction of family records. Therefore I'm interested in whatever genetic testing might be able to tell me about my ancestry.

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    13. Religious zealots care about "happiness". Scientists care about knowledge. Who cares if the knowledge makes you happy or sad? That's irrelevant.

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    14. I know you think that my happiness is irrelevant when you are telling me what I should, or should not, do.

      According to your logic, being "fascinated" or "excited" is also irrelevant. Right?

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    15. No. Fascination and excitement drives science. The point is to learn things no matter what. Happiness, not so much. As you say, learning things may not make you happier.

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  9. Genetic testing gets tangled in all sorts of powerful, and not-very-sensible, feelings people have about their identity. Good examples are the many cases where an adopted child is raised from age 1 by a family, who put in enormous love and effort. Then the adult child decides to find out "who my real parents are". Or men who have their Y chromosomes tested to find out "which tribe I came from", ignoring the 99.9 % of their ancestry that came from all sorts of other people.

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    1. There are lots of people who are absolutely convinced that they belong to some particular ethnic group. Then the DNA results come back and they learn that they mostly belong to some other ethnic group. They aren't happy.

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    2. But they might become better people for it. There was a case in the news a few months back of a white supremacist who took a test which told him he wasn't nearly as Aryan as he supposed...

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    3. JB: "There was a case in the news a few months back of a white supremacist who took a test which told him he wasn't nearly as Aryan as he supposed..."

      Is he now a beige supremacist?

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    4. Larry wrote:

      There are lots of people who are absolutely convinced that they belong to some particular ethnic group. Then the DNA results come back and they learn that they mostly belong to some other ethnic group. They aren't happy.

      That is certainly an example of startling results. But I would argue that many people do not belong narrowly to one local tribe. Testing of Y chromosomes is often presented as telling you which local tribe you "belong to". The statistical uncertainties from analysis of Y chromosomes aside, when you look at nuclear genes that picture cannot be correct. You have, at a remove of 10 generations (about 250 years) about 1,024 ancestors. Your genes don't come from all of them, but they come from about 360 of them. Are all of those folks from the same local tribe?

      When an African-American is told that his Y chromosome shows he "came from" a particular tribe in some African country, even if that is correct, is that true for his autosomes? Exactly what process determined that all of his ancestors in the U.S. carefully checked each other's tribal ancestry before marrying? Surely his genes came from all over the place.

      The same is true for local identities in Europe and Asia. We all have nuclear genomes that are a stitched-together patchwork of pieces from all over.

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    5. I'd be interested in whether anything in my genome showed various markers (1) in common with many others of Eastern European Jewish ancestry, (2) not common to non-Jewish Eastern Europeans, or (3) in common with people living in the Middle East 2000-3000 years ago.

      But anything that came back would be of interest to me. And I'd also be interested to learn about the various caveats regarding any attempt at interpreting the information.

      My late mother, on the other hand, would typify those people Larry described as folks who wouldn't be happy if results weren't what they expected. I know she was quite unhappy when I wondered where her blue eyes came from. :) (No, I haven't read Larry's apparently quite famous post on eye color.)

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  10. Anyway, the implied causality is just sloppy thinking.

    Pretty sure I'd attribute the divorce primarily to the infidelity rather than the genetic test.

    We would never say that a murder was caused by the discovery of the body, for example.

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