# Does getting a blood transfusion change your DNA? **URL:** \ **Category:** Factual Questions\ **Created:** [January 23, 2003, 12:54am UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326 "2003-01-23T00:54:38Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [January 23, 2003, 4:49pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/21 "2003-01-23T16:49:51Z")
> [@](#): > > \*Originally posted by MelCthefirst \* > So if you committed a crime and you were caught as a suspect shortly after a blood transfusion and had to give a blood sample for DNA examination to the police - would the sample not be your DNA yet and could you conceivably get off being linked to the crime? [No](http://www.straightdope.com/mailbag/mblood.html). (This link was found in **Qadgop** ’s linked thread as well.) ---
**Author:** ![Joe\_Mahma](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@Joe\_Mahma](https://boards.straightdope.com/u/Joe_Mahma)\ **Post date:** [January 23, 2003, 7:45pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/22 "2003-01-23T19:45:20Z")
> [@](#): > > \*Originally posted by CrazyCatLady \* > \*\*There’s no DNA in _mammalian_ red blood cells, no. There is, however, DNA in avian RBC’s, and I think in reptilian RBC’s. > \*\* Interesting, **CrazyCatLady**. I didn’t know that about birds and reptiles. I love this board! ---
**Author:** ![Zebra](https://avatars.discourse-cdn.com/v4/letter/z/c0e974/32.png) [@Zebra](https://boards.straightdope.com/u/Zebra)\ **Post date:** [January 23, 2003, 8:01pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/23 "2003-01-23T20:01:30Z")
A couple of things One Red blood cells are made in the bone marrow, right? So red blood cells do not divde and reproduce. Two If I just got a transfusion and I commited a crime and left some of my (now mixed) blood. Could the cops accidentally nab the person who donated the blood? I know one pint mixed in with all my blood would be pretty diluted but if they only need a tiny bit to test and that tiny bit happened to be from that nice donor… ---
**Author:** ![aeropl](https://avatars.discourse-cdn.com/v4/letter/a/f05b48/32.png) [@aeropl](https://boards.straightdope.com/u/aeropl)\ **Post date:** [January 23, 2003, 8:10pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/24 "2003-01-23T20:10:25Z")
> [@](#): > > \*Originally posted by Smeghead \* > \*\*Whew. No one noticed before I got a chance to fix this. I meant nucleotides, not nucleic acids. Nucleotides. That’s an example of somebody-or-other’s law, I’m sure. > > I quit for today. \*\* See how easy it is to spoof in you’re in a rush? But I admit mine was a little more irresponsible. ---
**Author:** ![X\_Slayer\_ALE](https://avatars.discourse-cdn.com/v4/letter/x/bbe5ce/32.png) [@X\_Slayer\_ALE](https://boards.straightdope.com/u/X_Slayer_ALE)\ **Post date:** [January 23, 2003, 8:15pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/25 "2003-01-23T20:15:41Z")
Same question from a different angle. If Red Blood cells do not have DNA, why do they always insist on a blood sample for DNA testing? If they use parts of the blood and not the actual RBC, what about in a crime scene where blood has been spilled? would the component that has the DNA be still viable after leaving the body? Why dont you hear on the news that the perps mouth was swabbed for dna testing (like they do in CSI) ---
**Author:** ![CrazyCatLady](https://avatars.discourse-cdn.com/v4/letter/c/dfb087/32.png) [@CrazyCatLady](https://boards.straightdope.com/u/CrazyCatLady)\ **Post date:** [January 23, 2003, 8:24pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/26 "2003-01-23T20:24:09Z")
Well, just off the top of my head, I’d say that they first compare ABO blood types. If the stuff at the scene is type B, and the suspect is type O, then that blood can’t possibly have come from the suspect, so there’s no need to move on to very expensive DNA testing. I’m not sure that you can check cheek cells for ABO groupings. Since DNA is essentially an inert chemical, it can be preserved even in dried blood, and I believe even in dried semen. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [January 23, 2003, 10:26pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/27 "2003-01-23T22:26:15Z")
> [@](#): > > \*Originally posted by Zebra \* > \*\* > Two > If I just got a transfusion and I commited a crime and left some of my (now mixed) blood. Could the cops accidentally nab the person who donated the blood? > \*\* I don’t know of any police department that goes to a crime scence, gets the blood, does a DNA test, and then searches for suspects that match the DNA. They use other evidence to catch the person, then use the DNA to confirm it. And if they know enough about you to catch you, they’ll have found out that you recently had a transfusion. Or, at least, it would come up before trial. Even then, as has been pointed out, most transfusions are just red blood cells, which don’t have DNA. > [@](#): > > If Red Blood cells do not have DNA, why do they always insist on a blood sample for DNA testing? Because blood also contains white blood cells, which do contain DNA, and blood collection is easy. You also get more DNA out of a tube of blood than, say, a cheeck swab. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 23, 2003, 11:49pm UTC](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326/28 "2003-01-23T23:49:08Z")
On the other hand, the cheek swab is very easy to do, and easy to get DNA out of, too, escpecially with PCR technology. When I was in high school, we all produced samples of several grams each of our own DNA, from cheek cell samples. [Previous page](https://boards.straightdope.com/t/does-getting-a-blood-transfusion-change-your-dna/150326.md?page=1)