Behold, the Chimera!
For thousands of years, a chimera has been held to be a mythological creature, a beast made up of pieces of other beasts; lion, snake, goat. So when you hear “chimera” you might be more inclined to think of the creature on the left than on the smiling young lady on the right.
Yet the creature on the left is the fruit of a great imagination, while the girl on the right is the real deal, an authentic chimera.
When Demi-Lee Brennan was 9 years old a viral infection destroyed her liver. With days to live one slim chance emerged; a liver transplant from an unfortunately deceased 12 year old boy. She went through surgery and could expect, at best, a lifetime of taking inmunosuppressors to prevent rejection of the new liver.
What she, her family, and especially the doctors WEREN’T expecting, was for her to switch blood type.
The result has landed the surprised and very happy and healthy girl in the prestigious New England Journal of Medicine. Demi-Lee was O negative, and the boy her transplant came from O positive, so it was with considerable surprise that doctors, upon tests in response to an illness months after her transplant, they found that she now tested O positive. The surprise turned to amazement when they found that, in fact, the new blood cells actually belonged to the donor, genetically. Not just the red blood cells, the lymphocites, inmune cells, were genetically like the boys, and they were MALE, with an XY chromosome type.
As if this weren’t enough, over time the girls blood was replaced by the boys, so that today she her blood “belongs” genetically to another individual, making her a human chimera. This has the added benefit of completely preventing the rejection of her new liver, so she doesn’t even need to take inmunosuppresants.
Doctors are basically at a loss to explain what happened. The closest explanation is that stem cells from the liver separated and migrated all the way to the bone marrow, where they started to differentiate into blood cells. Sound a little far fetched? It is, it’s unbelievable, and a one of it’s kind case.
“Life finds a way” Malcolm, Jurrasic Park
Hello,
This is Demi Brennan’s mum, Kerie Mills.
Thankyou for publishing such an amazing story about Demi. She has had a wonderful journey and is now a very healthy 15 year old. She can do any sport and loves to sing, she wants to be an Australian idol one day.
We are in contact with the donor family through our red cross and they love to hear how she is going. We thank god and the doctors everyday for her second chance of life but most of all we thank the donor family.
Demi hopes by being the one in six billion girl doctors can learn how this happened and why so it can benefit other transplant patient.
Cheers. kerrie Mills, a very proud mum.
Hello Kerie,
Thanks so much for stopping by to comment. I’m a biochemist and found the case of your daughter as inspiring as it was interesting. I’m glad to hear she’s doing well, please send her my best from Madrid, Spain.
Claudia
It sounds so fantastic that I can’t help thinking that occam’s razor suggests a simpler explanation: that doctors made a series of errors and her original blood type was O postive to begin with. I know they say both her parents are O negative, but there’s an uncomforatable explanation there too…
Admittedly, that wouldn’t explain her XY chromosomes. But bottom line, no matter what happened, she seems to be happy and healthy and that’s wonderful.
John, the study was published in the New England Journal of Medicine. I’ve read the original study by the way. The paternity was confirmed through genetic tests; she’s their biological daughter, both of them.
Additionally they didn’t just check her once and saw one type of cells and check her again and saw another type of cells. In the middle she was looked at and had BOTH types of cells, the ones that correspond to her genome and the foreign ones. This is, by definition, a chimera. Now she exclusively has the blood cells of the donor boy, but if you check them against ANY OTHER cell in that girls body, they come up as belonging to different people.
It’s got to be one of the most unbelievably cool things I’ve read about it quite some time.
To me the very coolest thing is in comment #1, from her mum.
“a very healthy 15 year old”
Amen.