
After a bone marrow transplant, a man has two sets of DNA - mcenedella
https://www.nytimes.com/2019/12/07/us/dna-bone-marrow-transplant-crime-lab.html
======
dade_
DNA evidence alone would not convince me beyond a reasonable doubt. If DNA
'positive match' wasn't already being abused as evidence then this would have
little impact. DNA should only be used to prove someone is innocent (DNA
doesn't match) or support other evidence they are guilty. There are also
actual instances of problematic matches noted in the article as well.

~~~
wespiser_2018
Yea, but there is definitely a gradient or propensity of evidence that is
often lost. For instance, touch transfer DNA can deposit your DNA on a crime
scene if you interacted with the EMTs earlier in the day (Anderson case, 2012)
[1] which means very little, but if a suspect's fingerprint is in the victim's
blood, it's very likely the suspect was present during an attack. In the later
case, I think DNA evidence, the victim's in the case, would be evidence of
guilt, but needs to be part of a larger, coherent case.

[1]
[https://www.forbes.com/sites/marinamedvin/2018/09/20/framed-...](https://www.forbes.com/sites/marinamedvin/2018/09/20/framed-
by-your-own-cells-how-dna-evidence-imprisons-the-innocent/#101a7f0e4b86)

------
new_guy
There's been well documented cases of people taking on the personality traits
of their donors too, 'who we are' is literally in the DNA.

Even something as relatively simple as a blood transfusion contaminates you
and can fundamentally change who you are.

It's not as well studied or given the visibility it should be because of the
obvious implications.

[0]
[https://blogs.unimelb.edu.au/sciencecommunication/2016/10/15...](https://blogs.unimelb.edu.au/sciencecommunication/2016/10/15/organ-
transplants-a-change-of-heart-in-more-ways-than-one/)

[1] [https://www.medicaldaily.com/can-organ-transplant-change-
rec...](https://www.medicaldaily.com/can-organ-transplant-change-recipients-
personality-cell-memory-theory-affirms-yes-247498)

[2]
[https://www.ncbi.nlm.nih.gov/pubmed/1299456](https://www.ncbi.nlm.nih.gov/pubmed/1299456)

[3] [https://listverse.com/2016/05/14/10-organ-recipients-who-
too...](https://listverse.com/2016/05/14/10-organ-recipients-who-took-on-the-
traits-of-their-donors/)

~~~
pergadad
I don't know if there's more to this rabbit hole, but a few self-reported
cases (placebo effect?!) and a theory with some gaping holes don't seem to me
like "well documented cases".

If there are physical changes you can expect some effect on personality - say
if a new heart is able to more efficiently transfer blood the patient might
find herself more prone to physical activity. Or a better kidney and liver
might affect food preferences. New blood type might offer have some wider
effect but even that's a still very much questionable field of research.

To latch onto the example given in all your links, there are no taste
receptors in the heart and neither is there any indication that memories are
saved in the heart. Spinal cord - yes, especially if it's about movement. But
not in organs like the heart which give much more basic input and have far
fewer connections to the rest of the neural network. There is no chicken
nugget and beer neutral network linked to the heart - and if there was,
chances are any organ transplant would have severed them.

~~~
perl4ever
It's been suggested that gut microbes affect mental functioning - maybe a
surgery/transplant could affect the immune system (not to mention
immunosuppressive drugs would be a given, right?) which in turn would affect
which microbes thrive, and therefore personality.

------
Laforet
White blood cells frequently infiltrate soft tissues in order to do their duty
so it's quite plausible that some donor DNA sequence will be found in other
organs.

I couldn't seem to find a link to the original report in the linked article
however it would not surprise me if some of the forensic techniques replied on
testing for mitochondrial DNA as it tends to be better preserved in the
natural environment. Human cells are known to exchange mitochondria so mtDNA
is more likely to display chimerism, especially in this case where the donor
is matched to the recipient.

------
crooked-v
Also see natural genetic chimerism, which is extremely rare but not unknown in
humans.
[https://en.wikipedia.org/wiki/Chimera_(genetics)#Humans](https://en.wikipedia.org/wiki/Chimera_\(genetics\)#Humans)

~~~
maxerickson
I don't think the prevalence is well understood (situations where it is
necessary to prove it out aren't common).

I went to school with someone that had different colored eyes, something that
is much more common than the discussion at your link.

~~~
patall
Of course we do not know exacty but there are multiple levels of evidence now
that chimerism is very rare. One example would be cancer sequencing were you
compare DNA from the cancer to a control tissue. I haven't heard of any of
those mentioning any cases. The other case would be the recent GTEx concortia
that sequenced upto 40 tissues of 600+ humans and did not detect any obvious
chimera cases.

Different colored eyes one the other hand my be caused by a lot of things like
no-genetic reasons, but also somatic (i.e post egg fertilization) mutations
like loss of one chromosome copy and others.

~~~
perl4ever
What is the probability of a (randomly selected?) control tissue of a
"average" chimera having different DNA, though?

I have no idea, but intuitively it would make a big difference in what
fraction you detect.

------
jedberg
My friend donated marrow to his brother. We always joke about how his brother
can commit crimes willy nilly and then pin it on him, or better yet, they
could commit crimes together and get away with it by taking advantage of the
doubt that would be introduced by them both having the same DNA.

~~~
perl4ever
There was a case in the news like that, where a pair of twins were implicated,
and they tried to argue that since it was impossible to tell which one of them
it was, neither could be convicted.

~~~
PopeDotNinja
Probably makes a better movie than reality. I wouldn't bet my future on that.
A prosecutor might jail one arbitrarily by spinning the story the right way.

~~~
klyrs
An acquaintance of mine has an identical twin. For a time, they shared a car,
and one of them got nabbed by a red-light camera. His face was captured rather
faithfully, but not in enough detail to distinguish between the twins. Both
showed up to court, both plead the fifth; case closed, no ticket.

------
mirimir
> The most unexpected part was that four years after the procedure, the DNA in
> his semen had been entirely replaced by his donor’s.

That blew my mind. Because it's my understanding that the germline is too well
segregated from somatic tissues. Even stem cells.

But then, I see that the patient previously had a vasectomy. So there are
arguably no sperm in his semen. And it's not surprising that the donor's stem
cells have replaced his prostate etc.

------
chiefalchemist
Things like this story, epigenetics, etc. should really have us questioning
our understanding of gentics. We don't seem to be as static and unique as we
thought. There seems to be more going on here. More yet to be known.

------
known
Sounds like
[https://en.wikipedia.org/wiki/Chimera_(genetics)](https://en.wikipedia.org/wiki/Chimera_\(genetics\))

------
myrryr
Bone marrow makes stem cells. Stem cell become the cells required in different
areas in the body.

Like, this isn't unexpected.

~~~
eximius
Many things are unexpected in hindsight.

~~~
myrryr
It may help that I have an ex who was in stem cell research, but I always
thought that marrow transplants would make a Chimera.

Hell, people were trying to cure HIV based on this.

At least for me, this is a TOTAL lack of surprise.

I would have been super surprised if it didn't.

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fiftyacorn
I wonder if we will see this being used in professional sport?

~~~
jeffnappi
The procedure to get a bone marrow transplant is horrific. It involves
incredibly painful procedures combined with necessary immune system
suppression.

~~~
fiftyacorn
They dont need to get the proceedure - they just need to get a medical record
of the procedure.

Anyway nothing surprises me the lengths professional athletes will go to to
win

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buboard
we need mass marrow transplants to confuse dna identification systems

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philshem
> After a bone marrow transplant...

