Healthy babies can develop from abnormal embryos

A group of Cambridge scientists made a discovery that will help to better understand the processes of embryonic development and develop methods to combat genetic abnormalities of the fetus. Research has shown that any embryo has everything necessary to develop into a full-fledged child, and scientists have also managed to establish (for the first time in the history of science) at what stage of development it is possible to understand that there will be any deviations in the future organism.

One of the Cambridge staff, Professor Magdalena Zernicka-Goetz, who became the author of the revolutionary study, once went through a difficult experience associated with her pregnancy. At the age of 44, Magdalena, who was then carrying her second child, was told by doctors that the results of a placenta biopsy indicated that her child might be born with Down syndrome. As the doctors explained, about 1/4 of the cells in the placenta were abnormal, and they suggested that the woman have an abortion. After questioning her colleagues, Magdalena found out that with such test results it is impossible to say with 100% accuracy that the child will be born with abnormalities, and this influenced the woman's decision to keep the baby, who was born on time and completely healthy. This is what prompted the woman to study the processes of embryo development in more detail in order to reduce the number of abortions associated with inaccurate tests.

Researchers studied rodent embryos, some of whose cells contained the wrong number of chromosomes, after a series of experiments it was proven that at the early stages of development some anomalies in the chromosome set can disappear on their own. Specialists created embryos with wrong sets of chromosomes, but observations showed that abnormal cells die due to apoptosis (the mechanism of cell death), while healthy cells continued the normal process of division.

In the first experiment, the researchers mixed abnormal and healthy cells 50/50, in the second 3/1, but the result was similar, with one exception - some of the abnormal cells did not die, but in both the first and second experiments, the biopsy showed the presence of abnormal cells, which confirms the possibility of an error, which happened in Magdalena's case.

The human embryo contains 23 pairs of chromosomes, one of which is sex chromosome (XY and XX), and the rest are autosomes. Changes in the number of chromosomes lead to various fetal developmental abnormalities, the most common example being Down syndrome, when the 21st chromosome has three copies instead of two.

As a rule, such disorders become the main cause of death in newborns; the only viable form of the disorder is trisomy (the formation of three copies of autosomes), which occurs during the development of Down syndrome.

Most often, the formation of three copies occurs in the 16th chromosome, which invariably leads to a miscarriage.

The absence of one of the chromosomes (monosomy) has more severe consequences, since in this case the embryo dies, with the exception of the loss of one of the sex chromosomes in women, which causes Turner syndrome - deviations in mental and physical development (dwarfism).

Extra copies of sex chromosomes do not have such a negative effect on the development of the embryo, but children may experience mental retardation.

Women over 40 have a higher risk of developing abnormalities in the chromosomal set. There are now tests that can suggest the presence of genetic pathologies. From the 11th to the 14th week, women are offered a chorionic biopsy, in which samples of the placenta are removed and examined for the number of chromosomes.

There is also another test that examines amniotic fluid cells (administered between 15 and 20 weeks) and the results of this study are considered more accurate.

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