MemeMachineGo!

There’s such a thing as a human chimera: a person whose body includes cells as genetically distinct as siblings’. “Blood chimeras” shared blood with a fraternal twin in the womb (and can even have two distinct blood types.) Others are thought to be the result of fraternal twins merging at an early stage of development, resulting in one fetus. A 52-year-old woman learned she was a chimera when genetic testing revealed that her biological children didn’t seem to be hers.

She and her children underwent genetic testing for a possible kidney transplant. Completely unexpectedly, two of her three children tested as genetically not hers. A mix-up of babies was ruled out, and she and her husband had not undergone in vitro fertilization, so it was absolute that her children were hers. […] The cells in her body are a mosaic of genes from both of the original embryos. The cheek cells from which the genetic testing was done were from one of those embryos, but at least some of the cells in her ovaries came from the other. Interestingly this genetic oddity gives her a better-than-usual chance of having a successful kidney donation, as her immune system does not reject as foreign either of two distinct tissue types. She would, however, be a poor candidate as a kidney donor were she in that position, due to the likelihood of two tissue types being present in her kidneys.

Rejected blog entry titles: “No, Bellerophon! This one’s friendly!”