General, Research, Technology

Do chimeras exist among people?

More recently, we told you thatChinese scientists managed to achieve the birth of a chimera of a pig with monkey cells. If you suddenly missed this news, be sure to read it, and subscribe to us in Telegram so as not to miss important events from the world of science and high technology. However, after reading this material, you might ask: "Is there any possibility of creating chimeras with the participation of man?" The answer to it may not be as obvious as it seems at first glance. Chimeras not only can exist, but also quite successfully live among us. And, if based on the definition of what a chimera is, then this is true.

Are there any chimeras among us? The answer will surprise you!

Chimeras among us?

Let's finally understand the terminology. A chimera is an organism that has several sets of DNA. As you know, we are all born with a certain set of genes, which determines our personality. But if you do not “mix” foreign DNA at the time of fetal maturation, then how to create a chimera? The answer is quite simple, although strange at first glance - to transplant the bone marrow from one person to another.

Nevada resident Chris Longsuffered from leukemia several years ago. With this procedure, a bone marrow transplant is indicated. Mr. Long was lucky to find a donor and the operation was successful. But 3 months after the procedure, during the patient’s blood test, the doctors noticed that his blood DNA had changed. Now it belonged to the man who saved Chris's life. However, the story did not end there.

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4 years after the rescuenot only Mr. Long’s blood was affected. Smears taken from his lips and saliva also now contain both his DNA and the donor's DNA. What is even more surprising is that the DNA in the blood and even the seminal fluid has been completely replaced. The only tissue that has retained only the DNA of the “owner” is the hair on the chest and head. Thus Chris Long technically became a chimera.

Before you is a real chimera. Her name is Chris Long

In fact, tens of thousands of people annuallygo through bone marrow transplantation for blood cancer and other diseases, including leukemia, lymphoma and sickle cell anemia. Although it is unlikely that any of them will turn out to be a criminal or a victim of a crime, the possibility that this will happen cannot be ruled out.

The doctor does not need to know how much DNAa donor will be present in the patient’s body. Because this type of chimerism has no effect on the body of patients. Their brain and their personality remain unchanged. Says Andrew Rezvani, director of the blood and bone marrow transplant department at Stanford University Medical Center. Patients also sometimes ask me what it means for a man to have the chromosomes of a woman after a transplant or vice versa. But that doesn’t matter at all.

But for a medical examiner this is completely differentstory. In the course of collecting DNA evidence from the crime scene, investigators proceed from the fact that each victim and each criminal leave behind one identification code, so the presence of chimerism can play a key role here. Moreover, a similar case has already occurred. In 2004, Alaskan investigators uploaded a DNA profile extracted from the sperm of the alleged offender into a DNA database. He matched a potential suspect. But there was one problem: during the attack, this man was already in prison. It turned out that the real culprit of the investigated case was a bone marrow transplant. And the brother was the donor, who was in prison at the time the crime was committed.

At the same time, the question remains open: and what kind of DNA will a child born if one of the parents is a chimera possess? Transplantologists agree that with a “foreign” DNA, the child would also be a “foreign”. But this hypothesis has not yet been confirmed in practice.