You could secretly have a twin unnoticed
A woman once suffered from kidney failure and her three sons were tested for the profile matches. The results revealed interesting insights. They showed the DNA of only one son among the three matched with the mother, while the other two sons remained unmatched. The mother confirmed to the doctors it is one hundred percent sure that she birthed the other two sons too. Taken aback by the results, the doctors decided to conduct further more investigation into the matter. They found yet more interesting factors that the mother’s genetic profile showed two different sets of DNA instead of one. Scientists from Genetic engineering were involved in this case and came to a conclusion that the mother has a condition called “Chimerism."
CHIMERISM
What is Chimerism?
Chimerism is a condition where people have two sets of DNA when a single organism is composed of cells with more than one distinct genotype.
How do you know if you have Chimerism?
Usually, the condition of Chimerism goes undiagnosed. But with specific biomedical tests, it is identified.
Generally during a DNA test, if the test results indicate two or more different sets of DNA, the person is said to have Chimerism.
Another most commonly known method to identify Chimerism is when the person has different skin pigmentation on various parts of the body or eyes being in different colors.
Intersex i.e., presence of both the sex genitals or the genitals being unclear.
Presence of any autoimmune disease.
Why do you get Chimerism?
During pregnancy, when the transfer of nutrients takes place, the stem cells from the growing fetus are sometimes transferred to the mother and vice-versa, resulting in Chimerism.
During IVF treatment, to increase the probability of success for pregnancy, multiple embryos are used.
During blood transfusions
During bone marrow replacements. The person may have a mix of DNA with that of the donor. Since it continues to regenerate, the DNA may match only to that of the donor.
What are the types of Chimerism?
Depending on the different probabilities by which Chimerism may occur, they are of various types:
- Micro-chimerism: The presence of different types of cells that are genetically different from that of the host. If the person retains a large portion of genetically different types of cells, it results in the development of autoimmune diseases over a period of time in their lifetime. This may also occur due to the vanished twin. In such conditions, the other surviving twin might absorb some or whole portions of the deceased twin.
- Germline Chimerism: This occurs when the germ cells are not genetically identical to their own cells.
- Artificial Chimerism: A person is said to have artificial Chimerism when one of the genes is inherited from the mother, and the other from any medical procedures such as transplantations.
- Tetragametic Chimerism: It is a congenital condition where two separate sperms fertilize two different ova, but these two aggregate into one later in the Zygote stage, which ultimately leads to the merging of two unidentical twins having different cell lines.
- Twin Chimerism: This is an extreme form of Chimerism, where the mother conceives a pair of twins and eventually when one of the twins is deceased, the other surviving twin might absorb a few cells from the other twin and result in Chimerism.
Effects of Chimerism in criminal cases and family law
Chimerism acts as a block in criminal cases and family law cases where the DNA results might be contradictory to the original facts. The most famous case is in 2002, a woman named Lydia Fairchild was denied public assistance when her DNA test results showed she wasn’t the mother of her children. One of the lawyers who had enough knowledge about Chimerism put forth the possibility of this condition and asked for further investigation in defense. Later they found out that Fairchild herself was a chimera with two different sets of DNA and the children could have either of the sets of genetic material.
Chimerism between humans and animals
Yes, there are several scientific pieces of research being held between humans and animals to understand the nature of various diseases and to overcome them, to check for replacement of human organs with those of animals if they are compatible. Famous researches include:
Chimerism between humans and pigs- in 2017, a Chimerism between humans and pigs is created and the genetic material from humans has survived around 0.001% cells and the remaining being pig cells.
Another famous research for Chimerism between humans and animals include the Chimerism between human and monkey- this is a project conducted by the Salk Institute of the USA and the Kunming University of China, where human DNA is injected into a monkey’s embryo and allowed to develop only for few days. At the end of the experiment, it showed a major number of human cells along with monkey cells and it was inferred that these cells might further form organs too. Hence it opened for further investigations if this can be used for brain transplantations.
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