Chimerism is a very rare type of genetic defect, which happens when a person carries more than 1 type of DNA in his body.
Generally, this change does not cause symptoms, but changes such as asymmetries and deformity in the body of the carrier can occur, or in rarer cases, hermaphroditism.
This situation is different from mosaicism, in which the person may present genetic changes, which are due to a mutation in the genetic material. Know what it is and how to identify mosaicism.
Chimerism can happen in 2 ways:
1. Natural or genetic chimerism
It is the classic form of chimerism, which originates when 2 or more embryos merge, forming one. Thus, the baby will be born with 2 or more different types of genetic material, as shown in the following figure:
A person with this disorder may have 2 or more different types of DNA in the body, and if the DNAs are of the same sex, there are usually no serious consequences for the person's life, with or without some signs, such as asymmetries of the body, skin color or eye pain, for example.
However, if they are of different sexes, the person will be born hermaphrodite. Understand what it is and how to identify hermaphroditism.
2. Artificial chimerism
It happens when the person receives an organ transplant, such as bone marrow, and the DNA of the organ is incorporated into the tissues of the person's body, and can be detected through genetic tests. This situation is beneficial, as this means that the organism of the transplanted person has accepted the organ well, reducing the risk of rejection.
Another form of chimerism that has been demonstrated is known as micro-chimerism, and it happens during normal pregnancy, in which some cells of the mother, or even of a twin baby, can be passed from one to the other, and the permanence of these cells it can last for years.
There is also microquimerism that happens through blood transfusion, in which the DNA of the transfused blood cells can last for a few days in the recipient's circulation.
Although this type of chimerism has not been shown to cause damage to health, some research has shown that it may be associated with the development of autoimmune diseases.
