DNA: What are the chances of a person having more than one kind?

Question

I remember seeing on a medical show on TV (Famous Diagnoses) the extremely rare occurrence of people having more than one kind of DNA. For example they tried to take one woman's child from her claiming it wasn't hers because the DNA test came back and it showed no relationship. It later turned out that depending on where on her body they obtained the cells she had 2 types! One showed that indeed the girl WAS her daughter

Another woman had one DNA on one side of her body and a different one on the other. In fact looking closely, the skin tones were even different.

Can anyone tell me where I might get references to this kind of thing?

I greatly appreciate the replies -- thank you. Does anyone know of a specific sourse I can go to for more information?

I just looked up "chimerism human" on the internet and got some hits --- this is what I needed -- thank you VERY much!!!!

Christine and Daniel

I GREATLY appreciate your taking the time and trouble to answer. I've started writing fiction and I needed this for a portion of a plot in a new novel. I could not remember the name of the condition and could find no information -- and my memory is not that great. Thank you again.

Answer 1

It looks like this has been pretty well covered, but I wanted to note that in cases where two embryos transfer cells or merge into one early in development one may have a male genotype (XY) while the other has a female genotype (XX). Unless one genotype is in a small minority the usual result of this is massive confusion when the embryo tries to build the reproductive tract because it is getting conflicting signals. Usually things get sorted out pretty well and the person has most of the structures needed for one sex or the other, but the ovaries or testes don't develope properly (gonadal dysgenesis) and the person is sterile.

Sometimes the person is what is medically called a hermaphrodite (although this condition may occur in someone with no Y chromosome). Unlike the common perception, this does not mean they have two fully-functioning sets of genitals! It means that when you look at a tissue slide from the gonad both tissue typical of the testis and tissue typical of the ovary is present. This situation usually requires removal of the ovotestis, as it is called, because of a heightened risk of cancer.

There is one case on the books of a woman whose body was mostly composed of 46,XY cells (the usual male genotype) while her reproductive organs were mostly 46,XX (the usual female genotype). One gonad was an ovotestis while the other was a normal ovary. She managed to get pregnant and carry the baby to term.

This would be a great plot hook, because she could commit a crime and it would look like her brother had done it, while in her particular case her brother had died as an infant (and in a story could have never been born if the embryos fused). No one would suspect her because the perpetrator was a male!

Answer 2

Yes this can happen and it is a known phenomenon. These kinds of people are called chimeras. There are a few reasons for this happening. But i don't think blood transfusion is one. One way for this to happen is if fraternal twins share a blood supply and the cells in the blood mix. Another reason could be improper cell division during development. This condition is know as mosaicism though. In this case, when a cell undergoes faulty division, 2 different cell lines arise.
If you want references, try some genetics or rDNA technology textbooks.

Answer 3

Yes this is called chimerism, and is extremely rare. It's probably to do with two eggs being fertilised - instead of developing into non-identical twins as would normally happen, they fuse into one embryo so that different parts of the baby end up coming from one or the other egg.

Answer 4

having a blood tranfusion can interrupt one's DNA