# DNA / surrogate question **URL:** \ **Category:** Factual Questions\ **Created:** [September 11, 2017, 9:05pm UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085 "2017-09-11T21:05:09Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [September 11, 2017, 9:05pm UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/1 "2017-09-11T21:05:09Z")
An embryo is created via in vitro fertilization and then implanted in a surrogate mother and carried to term. If a DNA test is done on the resulting child will he or she carry any of the surrogates DNA? ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [September 11, 2017, 9:07pm UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/2 "2017-09-11T21:07:19Z")
No. The embryo was genetically complete before it was implanted into the surrogate. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [September 11, 2017, 9:10pm UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/3 "2017-09-11T21:10:17Z")
Would the blood of the newborn still carry DNA of the host mother? If so, for how long? ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [September 11, 2017, 10:03pm UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/4 "2017-09-11T22:03:52Z")
> [@Ethilrist](#): > > Would the blood of the newborn still carry DNA of the host mother? If so, for how long? There is normally no blood exchanged between mother and fetus. Although nutrients etc are passed through the placenta, the circulations do not mix. So there should not be any DNA from the host mother in the fetus. However, some blood exchange does occasionally take place, and in such cases DNA could be exchanged with it. ---
**Author:** ![TSBG](https://avatars.discourse-cdn.com/v4/letter/t/77aa72/32.png) [@TSBG](https://boards.straightdope.com/u/TSBG)\ **Post date:** [September 11, 2017, 10:29pm UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/5 "2017-09-11T22:29:45Z")
It may be that it happens more often the other way around: [3 Human Chimeras That Already Exist - Scientific American](https://www.scientificamerican.com/article/3-human-chimeras-that-already-exist/) "More commonly, people may exhibit so-called microchimerism—when a small fraction of their cells are from someone else. This can happen when a woman becomes pregnant, and a small number of cells from the fetus migrate into her blood and travel to different organs. A 2015 study suggested that this happens in almost all pregnant women, at least temporarily." ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [September 12, 2017, 12:53am UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/6 "2017-09-12T00:53:46Z")
Some more background on this: The fetus is always effectively an allograft, tissue that is genetically different from the mother. An allograft would normally trigger an immune response from the host, so modulation of the mother’s immune response in pregnancy is an important and complex process. A principal role of the placenta is to form an immunological barrier between the mother and the fetus. Many things can go wrong, as described here: > **[Immune tolerance in pregnancy](https://en.wikipedia.org/wiki/Immune_tolerance_in_pregnancy)** > > Immune tolerance in pregnancy or maternal immune tolerance is the immune tolerance shown towards the fetus and placenta during pregnancy. This tolerance counters the immune response that would normally result in the rejection of something foreign in the body, as can happen in cases of spontaneous abortion. It is studied within the field of reproductive immunology. > The placenta functions as an immunological barrier between the mother and the fetus, creating an immunologically privileged site. For... ---
**Author:** ![Cub\_Mistress](https://avatars.discourse-cdn.com/v4/letter/c/ea666f/32.png) [@Cub\_Mistress](https://boards.straightdope.com/u/Cub_Mistress)\ **Post date:** [September 12, 2017, 1:09am UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/7 "2017-09-12T01:09:14Z")
> [@TSBG](#): > > It may be that it happens more often the other way around: > > [3 Human Chimeras That Already Exist | Scientific American](https://www.scientificamerican.com/article/3-human-chimeras-that-already-exist/) > > "More commonly, people may exhibit so-called microchimerism—when a small fraction of their cells are from someone else. This can happen when a woman becomes pregnant, and a small number of cells from the fetus migrate into her blood and travel to different organs. > > A 2015 study suggested that this happens in almost all pregnant women, at least temporarily." Absolutely fascinating! Thank you for this link. ---
**Author:** ![JWT\_Kottekoe](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@JWT\_Kottekoe](https://boards.straightdope.com/u/JWT_Kottekoe)\ **Post date:** [September 12, 2017, 2:01am UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/8 "2017-09-12T02:01:06Z")
I once read about a woman who, at autopsy, was found to have a liver that was genetically identical to one of her children. Apparently, stem cells from the fetus’s blood had out-competed and replaced her own liver cells. ---
**Author:** ![Oly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/oly/32/8255_2.png) [@Oly](https://boards.straightdope.com/u/Oly)\ **Post date:** [September 12, 2017, 3:36am UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/9 "2017-09-12T03:36:25Z")
> [@JWT\_Kottekoe](#): > > I once read about a woman who, at autopsy, was found to have a liver that was genetically identical to one of her children. Apparently, stem cells from the fetus’s blood had out-competed and replaced her own liver cells. Do you have a cite for this? Not that I doubt it. Well, OK I doubt it a little bit. Kind of a lot actually. Let’s just say I’m skeptical. Also curious, from a professional standpoint, as an autopsy pathologist. For starters, what would have prompted them to do a genetic comparison of the mother, child, and mother’s liver? That’s not really a routine part of an autopsy. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [September 12, 2017, 4:10am UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/10 "2017-09-12T04:10:11Z")
> [@Oly](#): > > Do you have a cite for this? Not that I doubt it. Well, OK I doubt it a little bit. Kind of a lot actually. Let’s just say I’m skeptical. Also curious, from a professional standpoint, as an autopsy pathologist. > > For starters, what would have prompted them to do a genetic comparison of the mother, child, and mother’s liver? That’s not really a routine part of an autopsy. The analysis would presumably be based on abnormal tissue findings attributable to an immunological reaction. Perhaps still not part of a routine autopsy even if liver disease was the apparent cause of death, but there are numerous studies of microchimerism, it appears to be a common phenomenon. Male cell microchimerism in normal and diseased female livers from fetal life to adulthood. > **[Male cell microchimerism in normal and diseased female livers from fetal life...](https://pubmed.ncbi.nlm.nih.gov/15962317/)** > > Male microchimerism is frequent in the adult female liver and is attributed to fetal cells originating from previous male offspring. It has never been studied in pregnant women, female children, or fetuses. We examined its frequency and cellular... Microchimerism in a female patient with systemic lupus erythematosus > [@](#): > > Male cells were found in every histologically abnormal tissue type that was examined, but were not found in histologically normal tissue. [http://onlinelibrary.wiley.com/doi/10.1002/1529-0131(200109)44:9\<2107::AID-ART361\>3.0.CO;2-9/abstract](http://onlinelibrary.wiley.com/doi/10.1002/1529-0131(200109)44:9%3C2107::AID-ART361%3E3.0.CO;2-9/abstract) (Sometimes, it really is Lupus) ---
**Author:** ![JWT\_Kottekoe](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@JWT\_Kottekoe](https://boards.straightdope.com/u/JWT_Kottekoe)\ **Post date:** [September 12, 2017, 4:54am UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/11 "2017-09-12T04:54:53Z")
> [@Oly](#): > > Do you have a cite for this? Sorry about that, it needs a citation. When I have more time I will look for it. There are other stories along these lines that are pretty amazing. Micro and large-scale chimerism are apparently much more common than previously thought, usually as a result of pregnancies. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [September 12, 2017, 6:11am UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/12 "2017-09-12T06:11:54Z")
> [@TSBG](#): > > It may be that it happens more often the other way around: > > [3 Human Chimeras That Already Exist | Scientific American](https://www.scientificamerican.com/article/3-human-chimeras-that-already-exist/) > > "More commonly, people may exhibit so-called microchimerism—when a small fraction of their cells are from someone else. This can happen when a woman becomes pregnant, and a small number of cells from the fetus migrate into her blood and travel to different organs. > > A 2015 study suggested that this happens in almost all pregnant women, at least temporarily." Thanks for posting that link. ---
**Author:** ![Oly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/oly/32/8255_2.png) [@Oly](https://boards.straightdope.com/u/Oly)\ **Post date:** [September 12, 2017, 12:53pm UTC](https://boards.straightdope.com/t/dna-surrogate-question/796085/13 "2017-09-12T12:53:10Z")
> [@Riemann](#): > > The analysis would presumably be based on abnormal tissue findings attributable to an immunological reaction. > > Male cell microchimerism in normal and diseased female livers from fetal life to adulthood. > > Microchimerism in a female patient with systemic lupus erythematosus “Presumably” is easy. I’d like to see the actual cite, read the real story, not the presumed one. And microchimerism, l’m down with that. Have been for a while now. But the claim (as I interpreted it, and if I misinterpreted please correct me) was that a whole organ, and a large one at that, was determined to be of chimeric origin. Not saying it didn’t happen, but, as said prior, I’m skeptical at this point.