Chimerism: The Science of Two DNAs in One Body
Chimerism sounds like something from mythology, but it is a rare and very real genetic condition. In its most common natural form, it can occur during early pregnancy and is often linked to Vanishing Twin Syndrome. When one twin stops developing, the surviving baby doesn’t “eat” or destroy the other. Instead, some of the twin’s cells can become part of the surviving baby’s developing body. Those cells may settle into different tissues and continue functioning normally, contributing to things like blood, skin, and other parts of the body. The result? One person walking around with two separate sets of DNA: their own in some tissues and their twin’s in others. This can also happen artificially through medical procedures such as bone marrow transplants. When a patient receives donor stem cells, their new blood cells carry the donor’s DNA, while the rest of their body retains its original genetic code. In a sense, that person becomes a medical chimera. The body identifies cells using mole...
