GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2006-01 > 1136398349


From: Jonathan Day <>
Subject: Re: [DNA] DNA FACT or FICTION?
Date: Wed, 4 Jan 2006 10:12:29 -0800 (PST)
In-Reply-To: <BAY111-F35A13D70337909758FD8C6E42A0@phx.gbl>


Came across this whilst wading through spam and
thought it would be worth replying even at this date.

First, no, a blood transfusion in itself won't impact
a person's DNA. It CAN be used as a carrier for
something that might alter your DNA, but that is about
it.

Second, yes, it is possible for a person to have more
than one DNA. The general term for this is "chimera"
and has really only been demonstrated in genetically
modified animals. (If you design a pig that will grow
a human organ, the human organ's DNA will contain
elements of pig DNA - there's some bleed-over between
the two.) As far as I know, bleed-over does not occur
in regular human-to-human transplants and has not been
demonstrated outside of the GM animal scenario I gave.

There is one exception to this. There are genetically
modified retroviruses which can embed DNA into a
person. This was a popular way to carry out gene
therapy, but was stopped when it was discovered there
was a much higher cancer risk than expected. If the
virus self-destructed or was otherwise eliminated a
significant enough time before all cells were
modified, a patient would end up with both modified
and unmodified cells.

Finally, when studying DNA, I feel certain there are
weird cases that could "break" standard tests. For
example, if you assume that a person has 2
gender-related genes (XX, XY or YX), then your test
will fail on those with extra X and Y genes. So-called
"supermales" and "superfemales" can have three or four
such genes. If you only examine two, there is a (low)
probability you will guess the gender of the person
incorrectly.

I don't know enough to be able to say if these
superfluous genes are going to be consistant or if
there's a chance they are going to be different. IF
(and only if) they could be different, different tests
that look at X and Y genes randomly could produce
different results.

I don't know how much of my ramblings will hold up to
inspection, but I -am- certain that chimeras and
genetic weirdness in the real world would make for as
compelling a story to the ordinary folk while giving
actual experts a chance of some entertainment too.

(There are probably a few readers on this list who
have discovered enough weirdness about their own DNA
to write a novel. The usual courtesy rules of
lists/virtual environments probably apply, but if you
stick to discoveries about yourself, I'm willing to
bet that next Christmas' best-seller list could have
at least one or two books from people here.)


--- Nelda Percival <> wrote:

> Hi,
> I was watching a Law and Order program, and wondered
> if what they presented
> was factual or fiction.
>
> Can a person have two different sets of DNA? now how
> they presented it... a
> test was done on blood at a murder sceen and a test
> on a cheek swab of a
> suspect. They were different. But then they found
> out the person had a blood
> transfusion, retested the person via blood and they
> had a match..
>
> So the question is: If you have a blood transfusion,
> then later a dna test
> can it have a different result then a cheek test?
>
> My sister asked me to ask this..and it makes me
> wonder too..
>
> If the answer is yes..how would it happen?
>
> Thank you
> Nelda
>
> Nelda's websites - Please visit
>
http://freepages.folklore.rootsweb.com/~bonsteinandgilpin/
> Gilpin DNA Project member
>
>
>
> ==============================
> New! Family Tree Maker 2005. Build your tree and
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>




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