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A couple from the United States has had an incredible story: after the birth of their child, a blood test shows that the man cannot be the child's father. At least not only - because further investigations show that he is also the boy's uncle. A medical phenomenon for which there is as yet no scientific explanation.
Blood group test excludes possible fatherhood of the man
The nightmare for all new parents: A couple has a child through artificial insemination, but after birth it turns out that this has a blood type that cannot actually be. Because the test had shown "AB" in the baby, although both parents have blood type A. As a result, the man could not be the boy's biological father, because if both parents are "homozygous" A or B, they cannot have children with a mixed blood type.
Father and son share only 25 percent of the DNA
As the result was also confirmed by a second test, parents grew worried that sperm donations might have been mixed up in the clinic as part of the artificial insemination. They sought help from a lawyer and also contacted Barry Starr, a geneticist at Stanford University who also runs the blog “Ask a Geneticist”. The latter recommended that a new test be carried out with a genetic test from the provider 23andMe, which he then evaluated and came to an astonishing result: "The man is two different things - father and uncle," said Barry Starr. According to the genetic test, father and son would only share 25 percent of the DNA, just like other close relatives such as uncles, nieces or nephews. With a "real" fatherhood, however, the child inherits 50% of its DNA from its father.
Foreign DNA can remain in the body for years
The next step was to examine the father's sperm. It turned out that 90 percent of his own DNA was found in it - but the other ten percent was that of his twin brother, who was never born. What sounds incredible, however, is not absurd according to the current state of research. It has been known for a few years that between the embryo and the mother during pregnancy are exchanged via the placenta, which remain in the body even after birth.
However, it is still unclear how this phenomenon can be scientifically explained. Until now, the so-called "mother cake" was considered a "barrier" that ensures that the mother's blood does not mix with the child's blood. But even after miscarriages or blood transfusions, the body picks up foreign cells that can persist for years. "There are many more twins than is commonly believed," said Peter Pharoah of Liverpool University a few years ago, according to The World. "During conception, the chance is one in 20, but only one in 40 births actually gives birth to a healthy duo, the rest of the nine months in the uterus do not survive," the newspaper quotes the researcher.
The first case of this kind
"As far as we know, this is the first known case in which paternity was initially excluded by standard DNA tests and later re-included as the result of analysis of different tissues," Barry Starr reports in a small study leading to the Case was released.
“This case of chimerism, which resulted from the false exclusion of paternity, is considered unusual; with the start of assisted reproduction, however, this result could occur with increasing frequency, ”continued the expert. (No)