This unlikely has any visible structural effects on the baby.Ĭhimerism doesn't always involve twins. If chimera twin are different sexes, then, in theory, different cells can carry different sex chromosomes. In this case, both babies would be considered chimeras and would have multiple sets of DNA. Twin embryos sometimes trade chromosomes with each other in their mom's uterus, since they have a shared blood supply. This phenomenon is called tetragametic chimerism.īut you don't have to have had a vanishing twin to be a chimera: Regular fraternal twins can also have the condition. In a move that's both bizarre and logical, the surviving twin acquires some of the dead embryo's chromosomes, causing them to end up with two distinct and separate sets of genes. The most extreme type of chimerism occurs when a twin dies early on in utero and the embryo disappears, which is known as vanishing twin syndrome. Researchers aren't sure how prevalent chimerism is: While it was once thought to be extremely rare, scientists are now estimating it’s more common than people realize. Fortunately, doctors eventually determined that she had a second set of DNA that matched. In real life, the most well-known case involving chimerism is probably that of Lydia Fairchild, who nearly lost custody of her children when DNA testing "proved" she wasn't related to them.
Whats a chimera tv#
It may seem like the stuff of science fiction, or at the least, high drama – and, in fact, the phenomenon has been featured in TV shows like House, Law & Order, and Grey's Anatomy. (It's worth noting that real-life human chimeras do not look like supernatural beings.)
The word comes from the mythical Chimera, a creature in Greek mythology that's part lioness, part goat, and part snake. What is a chimera?Ī person who has more than one set of DNA (the genetic material in our bodies) is a chimera, and the condition is called chimerism. Some people's bodies do indeed contain two sets of DNA – it's a condition called chimerism. Otherwise, a person could have two different blood types, which was something scientists once thought was impossible.Īs it turns out, high school bio didn't have all the answers. If you think back to your formaldehyde-scented high school biology class, you may remember learning two things about DNA: first, that it's the "code" for all our genes, and second, that each individual has one – and only one – set of DNA.
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