How does a person learn that they have chimerism? There is reason to believe that microchimerism may be the underlying explanation. For reasons not fully understood, many mothers report relief from rheumatoid arthritis during pregnancy. The baby’s stem cells may be acting to help protect the mother from her own autoimmune condition. A transient form of microchimerism can also occur after a blood transfusion or organ transplantation. Microchimerism has been detected in women who have never had a full-term pregnancy, but may have been unknowingly pregnant and miscarried. Frequently, this condition arises during pregnancy when a mother and the fetus exchange cells across the placenta. Microchimerism is defined by a person harboring a small percentage of cells that originate from another individual. In doing so, Lydia became the child’s mother and simultaneously, the biological aunt.Īn even more common form of chimerism is called microchimerism. Lydia unknowingly passed on her second genome to her baby. So when social services took a blood sample for routine maternity DNA testing, it did not match her child’s genome. Her twin did not survive to term and all that remained of the embryo were the cells that Lydia retained in her ovaries and other organs. What most likely happened is Lydia absorbed cells from her fraternal (non-identical) twin while still in utero. The remaining embryo incorporates the disappearing (“ghost”) twin’s cells into various tissues and develops to a healthy baby.īack to Lydia Fairchild, and her story. This is referred to “vanishing twin syndrome” because one embryo doesn’t survive and the embryo’s cells are absorbed by its twin and the mother. For the type of chimerism mentioned in this blogpost (also known as ‘tetragametic’ chimerism), the most common cause is a twin pregnancy that naturally reduces to a single baby. There are many types of chimerism, and various root causes. In essence, Lydia had delivered a child from her twin, thereby becoming both the child’s mother and biological aunt. Thankfully, a geneticist thought to test her cervical cells’ DNA, and indeed that DNA matched her son’s genome. Again, the third child’s DNA test excluded her from being the mother. Lydia was court ordered to have a witness present at the birth of her third child to take a DNA sample immediately following the birth. She nearly lost her two children to child protective services. Without knowledge of her condition, Lydia was accused of fraud. How could this be possible? Lydia conceived both of her kids naturally, carried them to term, gave birth, and was being told she was not their mother. Her husband was confirmed as their biological father, but the test indicated she was not the mother. She was required to prove a biological relationship to the kids, so she submitted DNA samples for routine DNA relationship testing. At the time, she was pregnant with their third child. Lydia applied for child support for her two children after separating from her husband in 2002. Perhaps the most famous example of a human chimera is Lydia Fairchild. Hospitals are usually ill-equipped to identify and treat chimeric individuals. When the hospital staff discovered he has two different, incompatible blood types flowing through his veins, they asked if he had received a bone marrow transplant. One young chimeric father I know reported being sent to a hospital after a car accident. As you can imagine, this condition can lead to confusing results when the person seeks medical care or relationship testing! So a DNA test result would be entirely different depending on where the sample was originally from (blood, saliva, fingernail clippings or hair, etc). One genome is found in one region or organ(s), while the other genome can be predominant in other organs or tissues. Chimerism is a condition whereby a person has not one but two complete genomes (or sets of DNA) in their body. Although this monster never existed beyond our collective imagination, the health condition is quite real. The term chimera is derived from a Greek mythological creature that was composed of a goat, a lion, and a snake. This might sound like science fiction, but this genetic condition is real and it silently impacts the lives of everyday people. The lab tests the alternate genome, which doesn’t match the DNA in his blood. At the scene of the crime, he only leaves traces of the alternate genome behind. OctoYou may have seen an episode of CSI where a man is exonerated from a crime he actually committed because he has two different genomes (sets of DNA). Posted 8:58 am by Kayla Sheets & filed under Chimerism, Paternity Testing, Vibrant Gene. Giving Birth to Your Sibling’s Baby: The Intriguing Condition of Chimerism
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