Boy, You'll Be a Woman Soon

Lisa Simpson

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In the current issue of Mental Floss (a magazine, for those who don't know) there is an article on stem cell research with a sidebar with the same title as this thread. It says in part:

There is an interesting twist, however. Take the case of Cedric Seldon, a 7 year-old leukemia patient at the Duke University Medical Center in Durham, NC. AFter a cord blood transplant, the stem cells successfully took root in Seldon's bone marrow. Yet, because the transplanted cells came from the umblical cord of a gril, the new blood cell they're generating carry two X chromosomes. And while this won't affect Seldon's sexual development, it does change his DNA. All respect to Seldon, but it brings to mind a curious scenario: If he ever commits murder and leaves blood at the crime scene, the police--working with the evidence--will be looking for a woman.
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I a little confused. Will his blood have one DNA type (XX) and his sperm another (XY)? Would this affect any other DNA typing a police department might do?
 
Lisa Simpson said:
I a little confused. Will his blood have one DNA type (XX) and his sperm another (XY)?
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An individual spermatozoon is either X or Y, not XY. If he ever commits murder and leaves sperm at the crime scene, the police should realize that they are looking for a man.
 
Re: Re: Boy, You'll Be a Woman Soon

The idea said:
An individual spermatozoon is either X or Y, not XY. If he ever commits murder and leaves sperm at the crime scene, the police should realize that they are looking for a man.
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It could be a gril.
 
Sorry, that's not quite what I meant. I know if there's sperm they will be looking for a man. What I meant was, would he still have X and Y sperm, ie, be able to produce boy offspring, and would it affect other DNA typing, for example, saliva or hair?
 
Lisa Simpson said:
What I meant was, would he still have X and Y sperm, ie, be able to produce boy offspring,
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Yes.

and would it affect other DNA typing, for example, saliva or hair?
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It might, depending upon the degree to which there is cross-contamination. (For example, if the hair samples have been contaminated with blood.)

What I would expect would be more likely is that the forensic scientists would find different kinds of DNA at the scene and start looking for a man and a woman.
 
Thanks, newdrkitten. So, he would have two different DNA "types". One for his blood and another for everthing else?
 
This topic was actually covered pretty well in an episode of CSI (hopefully or I'm gonna hear it). I believe it involved a rape case. The forensic scientists managed to track the DNA to one family line that had 4 brothers. Unfortunately, they ruled out each brother as the DNA sample they took from them (blood or saliva) did not match the semen. They eventually noticed some skin disorder that is a result of this phenomenon of carrying two sets of DNA that shows up in UV light. After researching this, they discovered that the rapist had the sperm of one person, and the blood/saliva DNA that was similar, but not the same.
 
Lisa Simpson said:
Thanks, newdrkitten. So, he would have two different DNA "types". One for his blood and another for everthing else?
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Yuppers.
 
One of the difficulties in convicting Ukranian serial killer Andei Chikatilo was that his blood group did not match the semen samples found at the crime scenes.
http://en.wikipedia.org/wiki/Andrey_Chikatilo
It was later revealed that Chikatilo had been originally ruled out as a suspect in the murders because his blood group was tested as different from semen samples left by the killer. The forensic scientists later claimed that Chikatilo must be a unique individual whose blood group showed up as different when it was taken from a blood sample than when it was taken by a semen sample. No other scientists at that time took this theory seriously and it was generally regarded that the samples had been mixed up or the tests simply botched.

Unfortunately for Chikatilo´s future victims this theory of non-secreters proved true some time later after his final arrest when it was found out that "a secretor status refers to blood protein antigen/antibody markers, which were used in the "classical" serological methods of blood identification in the days before the advent of DNA analysis. "Secretors" secrete these bloodmarkers into their other body fluids (saliva, tears, sweat, milk, etc.) while "non-secretors" do not. Therefore, you can determine the blood type of a "secretor" by testing body fluids other than blood, but would need actual blood to test the blood type of a non-secretor. About 80% of the population are secretors, and about 20% are non-secretors. Secretor status is of rapidly diminishing relevance today. Few labs (in the USA at least) do antigen/antibody analysis anymore because DNA methods are so much more definitive. Secretor status is irrelevant in DNA analysis."
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Lisa Simpson said:
Thanks, newdrkitten. So, he would have two different DNA "types". One for his blood and another for everthing else?
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Three.

Mitochondrial.
 
I am not a human doctor but leukemia is a cancer of the bone marrow/blood. I guess that in treating it they may destroy the entire existing bone marrow probably with whole body radiation and then transplant cells from another individual in this case stem cells which end up producing red and white blood cells. This results in the bone marrow and blood having one phenotype and the rest of the body having another. So his blood is female but the rest of him is male. You would never know it without a chromosome analysis.
 
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