Nephew of his own dad
The child inherited the genes not of the father, but of the unborn uncle
American geneticists reported a case of so-called "genetic chimerism": the child inherited the genes not of the father, but of his twin brother, who died in the womb.
Last year, a couple from Washington sought advice from Stanford University geneticist Barry Starr. In the summer, their son was born, conceived with the help of in vitro fertilization (IVF). After giving birth, it turned out that the child's blood type did not match any of the parents.
According to BuzzFeed News (This Man Failed A Paternity Test Due To His Vanished Twin's DNA), the first paternity test showed that the father is not really the father for the baby at all. At first, the upset parents decided that their sperm was mixed up in the clinic, but they said there could be no mistake. Then they tried to take a test in one of the accredited laboratories in the USA – for him they took a scrape from the mucous membrane of the inner side of the cheek. But just like the first test, it gave a negative result. Only additional genetic studies, including analysis of the genes of relatives, showed that the man was not the father, but the uncle of the child. "It was kind of eureka," said Barry Starr, who realized they were dealing with a so–called "genetic chimera."
According to experts, the reason for this rare phenomenon is the so–called chimerism. With it, the embryonic cells of two non-identical twins merge at the very beginning of pregnancy, which leads to the formation of two cell lines containing different genomes in the body of the surviving twin. At the same time, scientists believe that every eighth single birth begins as a multiple pregnancy. So, the man did not pass the paternity test due to the fact that the genes contained in his saliva and sperm were different. In addition, semen analysis showed that the genetic set inherited by his newborn son coincides with the DNA in the sperm of a man by only 10%. Scientists concluded that from a genetic point of view, the boy's father could be an unborn twin brother of an American who died in the womb.
Such cases are rarely detected, but they have been known about before. For example, in 2002, researchers reported a case when a genetic mother, according to a set of genes, turned out to be not a mother to her two sons at all, but a twin sister. This turned out during testing, which the woman underwent for a kidney transplant. A similar case was described in 2006.
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27.10.2015