Human chimeras, for real?

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According to the Greek mythology, the Chimera (also Chimaera) is a hybrid monster with the body and head of a lion with a snake for a tail and a fire-breathing goat head coming from its back. Aside from this, the term “chimera” has been used medically to describe animals having more than one set of genetic coding.

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In 2002, Lydia Fairchild demanded custody as well as public assistance from the Washington state after her separation with her husband. For her to be able to get assistance, she had to undergo DNA testing to prove that she is the mother of her children. But to her surprise, the DNA results were negative making her subject to further investigation into possible fraud due to her claims. Knowing of a surety that her children came from her own body, she contested this to the court but in still in vain.

In Boston, Karen Keegan faced the same situation after being diagnosed with kidney problems. Her children showed no genetic link with her after undergoing series of DNA testing to look for a potential donor. Her doctors sought further advice and she was suspected to have a rare medical condition of chimerism.

Given this knowledge, doctors of Keegan began tracking down any trace of DNA that will match with her children, which turned out to be her pre-removed thyroid nodule.

As for the case of Fairchild, one prosecutor came across the case of Keegan and ordered further tests which showed a genetic link between Fairchild and her children.

Human chimerism, a condition wherein a person possesses a unique set of genes has been crucial in the development of modern biotechnology. The possibility of this condition seems to prove all of the known rules of genetics wrong. However, due to researchers about this issue showed the the rules in genetics are not at all wrong. Human chimera, so it was called, is a result of a rather common occurrence during pregnancy.

Chimerism occurs in the embryo as one is developing – two fraternal twins’ embryos grow, but then one absorbs the other, incorporating the other's DNA into different tissues and organs of its body. In case the twins are of different sexes, hermaphroditism may result.

Human chimerism however is hard to prove. A number of evidences just cannot attest the occurrence of this condition since the other DNA is just a very small part of the whole DNA of the individual. But still, this may mark another phenomenon in the medical history.

Blogpost by: Sariah Kate Acama

References:

"She's Her Own Twin." ABC News. ABC News Network, 15 Aug. 2006. Web. 02 Feb. 2014.  <http://abcnews.go.com/Primetime/story?id=2315693&page=1&singlePage=true>.

Mike. "Chimera Mythology." Gods-and-monsters.com. N.p., n.d. Web. 01 Feb. 2014. <http://www.gods-and-monsters.com/chimera-mythology.html>.

Ace. “Weird: Kids' DNA Tested, Parent Informed The DNA Is Not A Match.” Ace of Spades HQ. 13 Sept. 2015. Web. 02 Feb. 2014. <http://ace.mu.nu/archives/118606.php>

"Human Chimeras." Web. Tumblr.com. Fuck Yeah, Medical Stuff!, n.d. Web. 02 Feb. 2014. <http://fuckyeahmedicalstuff.tumblr.com/post/33342058446/human-chimeras>