: BTW, any documentation of this happening? I mentioned it last night to Suz, RN, and she was skeptical that a person could have two sets of DNA.
Yep. And yep:
Take Karen Keegan, who discovered her chimera-ness at age 52. When Keegan needed a kidney transplant, she and her two adult children underwent DNA testing to figure out which kid's kidney would be the best match for mom. Surprisingly, the tests showed neither. In fact, according to DNA, Keegan's children weren't her children at all. The case confounded doctors for more than two years until, in 2000, the docs finally realized that Keegan's blood cells carried different genes from the cells in her ovaries---the long-absorbed twin was found.Oh, and yep:
Lydia Fairchild was pregnant with her third child when she and the father of her children, Jamie Townsend, separated. When Fairchild applied for welfare support in 2002, she was requested to provide DNA evidence that Townsend was the father of her children. While the results showed Townsend was certainly the father of the children, the DNA tests indicated that she was not their mother.
This resulted in Fairchild's being taken to court for fraud for claiming benefit for other people's children or taking part in a surrogacy scam. Hospital records of her prior births were disregarded. Prosecutors called for her two children to be taken into care. As time came for her to give birth to her third child, the judge ordered a witness be present at the birth. This witness was to ensure that blood samples were immediately taken from both the child and Fairchild. Two weeks later, DNA tests indicated that she was not the mother of that child either.
A breakthrough came when a lawyer for the prosecution found an article in the New England Journal of Medicine about a similar case that had happened in Boston, and realised that Fairchild's case might also be caused by chimerism. . . .
Fairchild's prosecutors suggested this possibility to her lawyers, who arranged further testing. As in Keegan's case, DNA samples were taken from members of the extended family. The DNA of Fairchild's children matched that of Fairchild's mother to the extent expected of a grandmother. They also found that, although the DNA in Fairchild's skin and hair did not match her children's, the DNA from a cervical smear test did match. Fairchild was carrying two different sets of DNA, the defining characteristic of a chimera.
I'm actually kind of surprised that Suz has never heard of this phenomenon.
Oh, and consider that chimerism is only detectable when FRATERNAL twins merge into a single embryo. If an embryo separates into two embryos, producing IDENTICAL twins, and then the identical twins re-combine into a single embryo, no one would know that the one embryo had ever been two.
Edited by Peter T Chattaway, 10 January 2012 - 07:20 PM.