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Crime Science

When a DNA Test Says You're a Younger Man, Who Lives 5,000 Miles Away (nytimes.com) 76

After a bone marrow transplant, a man with leukemia found that his donor's DNA traveled to unexpected parts of his body. A crime lab is now studying the case. From a report: Three months after his bone marrow transplant, Chris Long of Reno, Nev., learned that the DNA in his blood had changed. It had all been replaced by the DNA of his donor, a German man he had exchanged just a handful of messages with. He'd been encouraged to test his blood by a colleague at the Sheriff's Office, where he worked. She had an inkling this might happen. It's the goal of the procedure, after all: Weak blood is replaced by healthy blood, and with it, the DNA it contains. But four years after his lifesaving procedure, it was not only Mr. Long's blood that was affected. Swabs of his lips and cheeks contained his DNA -- but also that of his donor.

Even more surprising to Mr. Long and other colleagues at the crime lab, all of the DNA in his semen belonged to his donor. "I thought that it was pretty incredible that I can disappear and someone else can appear," he said. Mr. Long had become a chimera, the technical term for the rare person with two sets of DNA. The word takes its name from a fire-breathing creature in Greek mythology composed of lion, goat and serpent parts. Doctors and forensic scientists have long known that certain medical procedures turn people into chimeras, but where exactly a donor's DNA shows up -- beyond blood -- has rarely been studied with criminal applications in mind.

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When a DNA Test Says You're a Younger Man, Who Lives 5,000 Miles Away

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  • This would be an interesting premise for a crime lab / CSI type movie. Just add some murder, treason, shared love interest and all the tropes are there.
    • by aevan ( 903814 ) on Monday December 09, 2019 @03:25PM (#59502164)
      They already did it [fandom.com]
    • Honestly, I am all but certain that writers for several of the long-running crop of insipid CSI/NCIS/SVU tele.vision series are already working on the scripts.

      My wife loves those shows. I have to bite my tongue when they're on because the science and tech is generally pretty bad. But I do find it mildly interesting to see which news item from the past 6-12 months has provided the basic plot.

    • by Anonymous Coward on Monday December 09, 2019 @04:00PM (#59502294)

      Real life already had it. Lydia Fairchild [wikipedia.org] divorced her husband and applied for child support for their two kids. The DNA tests done conclusively proved that her ex-husband was the father, but she was ruled out as the mother.

      Her two children were taken away from her. The third child she was pregnant with at the time was born while under watch by a court appointed witness. An immediate DNA test was done on that child. Again, it showed that her ex-husband was the father, but she was ruled out as mother. Lydia's mother and father were consistent with genetic match for grandmother and grandfather though.

      Turns out she was chimeric.

      • by AmiMoJo ( 196126 )

        Reading the wiki article it seems that to its credit the court didn't actually take her kids away, despite the prosecution calling for it. Instead it did the right thing and properly investigated.

    • by skids ( 119237 )

      Screw crappy crime procedurals... think dystopian sci-fi. Some crazy gentic purism movement
      running around surreptitiously using such means to replace every guy's balls so all the babies come
      out as children of the cult leader.

      • Except that this guys' balls weren't what was replaced.

        He got bone marrow transplant.
        What he is producing is white blood cell.
        Of which there are lots in the semen (hence the high risk of HIV transmisison. You know the virus that infects white blood cells - such as Lymphocytes T).

        What this patient isn't producing is spermcells. These would have been produced by his balls which are still the original ones (so they would have shown up as his own DNA and the children would still have matching DNA).
        Except that l

      • Isn't that most of the plot of "The Boys from Brazil"?

        Monocultures are a really bad idea.

    • Comment removed based on user account deletion
  • The "germ line" stem cells, the ones that become eggs or sperm get segregate very early in the embryonic development. These cells are never intermingled with regular cells. The transport fluid might be something made in the marrow, or from blood cells made in the bone marrow and get the new DNA, but the actual sperm should be "original".
    • Yeah it doesn't make sense. Are there other 'carrier cells' in the semen besides the sperm itself in there?
      • by pesho ( 843750 ) on Monday December 09, 2019 @04:44PM (#59502534)
        It makes sense if you don't assume that the DNA in the semen comes from sperm. The bone marrow transplant procedure involves killing off of the patients bone marrow with alkylating agents or radiation. These treatment also stop sperm production because any rapidly dividing cell is going to be affected. Depending on the treatment anywhere between 20% and 90% of the patients will recover sperm production [nih.gov]. He is probably one of the unlucky guys and the DNA in his sperm comes from white blood cells, which in turn come from the donated bone marrow. Oh, and according to the article he also had vasectomy, so even if he is making sperm none of it is getting to the semen. Mystery solved.
        • The vasectomy was the real missing piece of the headline. At first reading this I was shocked, thinking we had spermatogenesis all wrong somehow, but it makes a lot more sense when you realize no sperm were in the sample.
      • Are there other 'carrier cells' in the semen besides the sperm itself in there?

        Yup.
        Like other body secretions, the semen is choke full of white blood cells.
        (That's why it's considered a risk of HIV transmission, you know: a virus which is carried by white blood cells - Lymphocytes T).

        These cells are the one which are produced by the marrow, so these are the reason why the donnor registers on semen DNA analysis.

  • Get out jail free card!

  • Freeze some semen before transplants.

  • Look forward to the Movie in 2022....

  • I'm interested in the applications for this affect when used with cross species bone marrow transplants [nih.gov].
    • In theory:

      well the bone marrow will start producing (mostly white) blood cells and will thus show up as the donnor in most of the body secretion where the cells are abundant (so the blood and saliva of the mouse will show up as "rat") but not other such as hair (still nearly 100% hair).

      In practice:

      You would need a compatible donnor. It worked between the rat and the mouse in the article. But before it works in human you would need a compatible donor.
      Remember, that marrow is going to produce mostly white blo

  • The police now consider DNA evidence as the gold standard for proving identity. The situation described here has some pretty serious implications for this. I wonder how long it will take for this argument to appear in a criminal case when a suspect is identified through DNA?

    • There is a high rated AC comment describing the case of Lydia Fairchild several posts up (in my view anyway). While not criminal, it was court involved and custody, etc. issues.

  • This may be the magic pill all the trans-wannabes have been waiting for. All they need is a bone marrow transfusion, and: Voila!

  • Another story (2 stories above) tells about gene therapy to live longer. And here this guy gets a lot of his DNA become 10 years younger, that should have an impact on his life expectancy. What would happen to that man if the donor had been a woman?
    • that should have an impact on his life expectancy.

      Nope.

      What would happen to that man if the donor had been a woman?

      Not much.

      Yes, bone marrow can differenciate into lots of different cell types. But most of them are blood cell types.

      Yes, white blood cells gets everywhere and in some palces are the major contributor to the DNA you're going to pick up.
      (Hence the donor DNA showing all over the place, but not in hair).

      But, it might surprise you, you're far from being entirely made out of white blood cells.

      So if the donor was a woman:
      - her white blood cell are going to show up in lots of places and thus thwart DNA tests
      -

  • Seems like if that happened then he'd be maintaining and producing cells that aren't his, so should be a foreign body. Seems like that would kill him.
    Since it's not, sounds like a study opportunity. Why isn't he rejecting those cells? Why isn't this producing cancer?

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