Swapping DNA in the Womb


A new study finds male genes in women’s brains, the first evidence of microchimerism in the human brain.

DNA from male cells, most likely from a fetus or sibling, are often found in the brains of women, according to a study released yesterday (September 26) in PLOS ONE. The findings are the first demonstration of microchimerism—in which cells that originated in one individual integrate into the tissues of another—in the human brain, and could have implications for disease.

“Knowing cells are in the brain brings home the idea that we’re a little more diverse than we thought we were,” said Nelson. “So conceptually, it may be more appropriate to think of ourselves as an ecosystem rather than a single genetic template.”

Researchers have suspected that the human brain may harbor microchimeric cells, which are present in other human organs, and previous studies in mice have shown that such foreign cells can break through the blood-brain barrier. But the study, led by Lee Nelson of the Fred Hutchinson Cancer Research Center in Seattle, revealed that microchimeric cells could not only migrate to the brain, but do so frequently: more than 60 percent of autopsied brains contained DNA from another individual.

Microchimerism most commonly arises during pregnancy when cells from a fetus pass through the placenta and into the mother’s body—and vice versa. The foreign cells can then migrate to various tissues and set up chimeric cell lines, which has raised many unanswered question about immune disorders and other links to disease risks. Other studies have found that fetuses can also acquire microchimeric cells from a twin or even from an older sibling, as some fetal cells linger in the uterus. In rare cases, microchimerism can occur from blood transfusions in immunocompromised patients.

Written By: Beth Marie Mole
continue to source article at the-scientist.com


  1. Okay, this is just… I don’t know what to say.  Bizarre and fascinating stuff.

    There’s always something new to learn.

  2. I remember hearing something about chimerism before – it caused problems in a legal case.  It was some sort of custody case – a woman’s DNA was different from her children’s DNA;  she couldn’t “prove” that she was the mother of children she had given birth to.  Apparently the DNA in her ova was different from that in the epithelial (cheek swab) cells used for testing.   The poor woman had to submit video of the births of her children, witness testimony, all sorts of evidence – but her DNA test at least temporarily trumped them all and her kids were taken away from her for a time.  She got them back after a second round of court appearances, but last I heard (this was a few years ago), she was still struggling.  I don’t remember what the original custody issue was, or why she underwent testing in the first place, but it was an interesting example of potential problems with relying on DNA tests in criminal cases.

  3. Yep, just when we though we had the solution to all crime, here comes science to mess it all up.

    Really interesting stuff. I wonder if cells can be transmitted by kissing. If the chimeric cells are found in the brain, wouldn’t that be a possibility? Talk about becoming one… If so, would long living couples who happily share their cells for a long time have more cells of their spouse than not so happy couples? And (sorry for getting messy) how about stray sperm cells? Most will not link up with an egg cell so where do they all end up?

    Lots of research still to be done. Good.

  4. “A new study finds male genes in women’s brains”
    May explain why male brains study women’s jeans…. 😎

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