Is it possible to have two DNAs in the same body?

Nucleic acids (Dna and Rna) are the basic building block molecules that control metabolic processes in all living cells and transmit hereditary traits.

DNA is present in the cells of all living things and is extracted in the same way from every biological sample. The Dna in a person's blood is identical to the Dna in their skin, sperm and saliva. Except for chimerism. Chimerism is genetically defined as the birth of two embryos formed by two eggs fertilized by two sperms as a single living being instead of twin brothers. For this reason, the Dna profiles in the skin and blood of chimeric individuals do not match, so they carry two Dna in the same body.

What is Chimerism?

The word chimerism comes from the Greek mythology of Chimera, a wild creature with the head of a lion, the body of a goat, and the tail of a snake that breathes fire from its mouth, where the limbs of many animals are united in one body. Although this creature is a figment of imagination, it now helps us to define a serious health problem today.

Kimerism is a rare genetic defect caused by the fusion of two separately fertilized eggs in the womb. Although the differences caused by mutations in the genetic material do not cause symptoms, in rare cases they can cause hermaphroditism differences on the body of the individual. The number of such chimeric individuals is very small. Each cell population originates and develops according to the genetic characteristics of its constituent organism.

In cases of chimerism, any change in the genetic code has an effect on both the anatomical and morphological structure of the organism. While the chimeric individual carries its own DNA, it also carries the DNA of its unborn twin. This situation is popularly known as "he ate his brother."

What are the Types of Chimerism?

Chimerism can be seen in many different ways in living things. It is possible to see changes in the eye color, skin color or blood type of chimeric individuals. In some cases, there is no change in the phenotype of chimeric individuals, but chimerism can be observed in their genotype. There are two main types of chimerism: natural chimerism and artificial chimerism.

Natural Chimerism; While two eggs, i.e. dizygotic twins, two eggs and two sperms will continue their lives as fraternal twins, one egg is divided into two by mitosis. Here it merges and continues its life as a single embryo. Therefore, there are 2 Dnavars inside. These people are congenitally chimeric individuals. Their incidence, that is, their prevalence in the society is low.

Artificial Chimerism occurs when the donor's DNA is passed on to the recipient with the help of cells in cases such as bone marrow transplantation and organ transplantation. Artificial chimerism develops later in the individual's body.

Cimerism occurs not only in humans, but also in plants and animals. In animals, it occurs when the egg is fertilized more than once, while in plants it occurs when the egg mutates and forms different tissues. Chimerism can give different characteristics to living things. Chimerism; While it occurs in animals by the union of fertilized eggs, it occurs in plants when mutations that occur during cell division form different types of structures.

Forensic Science and Chimerism

Chimerism cases question the perception in the scientific community that DNA tests cannot be altered by testable methods. For forensic science, the presence of a chimeric perpetrator or victim will make it more difficult to solve the crime. Chimerism cannot be understood without any suspicion, and to suspect it, we need to have no test results or to see a double Dnaprofile mixture.

Chimerism is not a new concept in the medical literature and has been the subject of scientific studies since the first case was reported. Dna testing is not the only evidence used to identify chimeric individuals born as composites. Current research hypothesizes that tests to minimize the risk of organ transplants will yield more effective results on chimeras.

In conclusion;

Cimerism is not always a condition that differs in appearance. It should be tested by consulting experts in the field. Various analytical methods and markers are used in chimerism analysis. You can visit our Forensic Sciences and Molecular Biology and Genetics section pages to learn more about chimerism, which today has an important position in the triangle of crime scene, victim and perpetrator.