What would a post-blood transfusion DNA test show?
December 9, 2004 11:48 AM   Subscribe

If I received a blood transfusion, and then went out and committed a crime, and got cut...is it possible that they would do DNA tests and get the donor's DNA?
posted by graventy to Science & Nature (15 answers total) 1 user marked this as a favorite
I think there was a CSI or Law and Order that was based around this premise in the recent past. The Bad Guy gave a saliva sample that did not match the semen/blood sample found at the scene and almost got off scott free!

So in the realm of Hollywood, yes. In the realm of Science....?
posted by robocop is bleeding at 11:53 AM on December 9, 2004

posted by drpynchon at 11:56 AM on December 9, 2004

Best answer: I tried Google with "blood transfusion DNA"

Second result was this

...But as far as blood transfusions confering the genetic identity of the donor to the recipient, it is not possible. Blood has three components, reb blood cells, white blood cells, and the fluid they are in called plasma. Simple blood transfusions deliver only red blood cells and plasma. The only job of a red blood cell is to delivery oxygen to all the tissues of the body. Transfusions are given to replace lost blood and plasma during surgery or some trauma so that the body can still deliver enough oxygen to the tissues. What is important about this is that red blood cells contain no nucleus, and therefore no individual genetic material. Why not give the white blood cells as well? White blood cells have too many...
posted by vacapinta at 11:56 AM on December 9, 2004

BTW, that link above does go on to point out that genetic identity is transferred with bone marrow transplants.
posted by vacapinta at 11:58 AM on December 9, 2004

The show in question was the Law & Order: Special Victims Unit episode "Weak".
posted by mmascolino at 12:16 PM on December 9, 2004

There was also a CSI episode called Bloodlines, but rather than a transfusion, the guy had something called Blaschko's lines or chimerism - he was made of two embryos that had sort of absorbed into each other, so his saliva had a different DNA than his semen. (Yes, I know that's a crappy explanation, but everything my cursory Google search turned up was either a CSI fan site or a medical article.)
posted by librarina at 12:49 PM on December 9, 2004

librarina: The NCBI Bookshelf is probably more helpful than Google for basic biology stuff. Here's some information on chimerism.

Also of interest is lyonization, where some parts of a woman's body have one or the other X chromosome inactivated, and therefore different traits (such as skin patches with no sweat glands). The genotype will still be the same though.
posted by grouse at 3:07 PM on December 9, 2004

To echo vacapinta's posting - a normal blood transfusion is of red blood cells only, which have no DNA. In fact, one approach (being researched) to reducing (eliminating) the problems of otherwise unacceptable donated blood (HIV, viruses, etc.) is to remove all DNA and RNA, something that would leave red blood cells as they are.
posted by WestCoaster at 3:17 PM on December 9, 2004

Response by poster: So, basically, my goofy murder ideas are 6 months old, in TV writer circles. Man, has CSI thought of every possible way to attempt to get away with murder?
posted by graventy at 5:07 PM on December 9, 2004

Alas, graventy, it will be difficult to write something that hasn't been seen on CSI, CSI: Miami, CSI: NY, L&O, L&O: Special Victim's Unit, L&O: Criminal Intent, or NCIS.

You can direct your anger at the older guy with the cane who plays the medical examiner on CSI. He's one of the main researchers for the show. :)
posted by xyzzy at 6:12 PM on December 9, 2004

Actually that L&O:SVU show was based on a real event. I have vague memories of seeing (possibly reading) about the original true crime. It was a Doctor who implanted vials of blood inside his arm in order to get out of a rape charge. I believe he was a gynecologist in a small town who raped several women. I recognized the plot immediately when I saw the L&O episode.
posted by Secret Life of Gravy at 6:55 PM on December 9, 2004

Graventy. What. The. Fuck? I used to be your roommate. Were you always this crazy?
posted by Arch Stanton at 6:58 PM on December 9, 2004

This is sort of related to the first comment, and it's mostly OT, but I seem to remember a Russian serial killer that they had an extremely hard time catching, because he was what is referred to as a non-secretor, meaning his blood and saliva didn't match his semen.

I'll have to do some Googling about that one.
posted by jackofsaxons at 9:22 PM on December 9, 2004

This guy.
posted by jackofsaxons at 9:26 PM on December 9, 2004

My favorite thing about that case is that the guy got away with it for so long because it was the USSR, Every suspect they arrested confessed!!!
posted by Megafly at 8:53 AM on December 10, 2004

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