Embryos-smokers
Scientists: smoking changes baby's DNA in the womb
Observations of the health of six thousand pregnant women have shown that smoking while carrying a fetus leads to changes in the structure of the baby's DNA in the womb, which indicates an increased risk of tobacco for the health of mothers and children, according to an article published in the American Journal of Human Genetics (Joubert et al., DNA Methylation in Newborns and Maternal Smoking in Pregnancy: Genome-wide Consortium Meta-analysis).
"It is extremely surprising to see how the same epigenetic changes in the structure of genes that are characteristic of smokers affect the same genes in the body of newborn children. Since embryos cannot smoke, all this is transmitted through the mother's blood and her placenta," said Stephanie London from the US National Institutes of Public Health.
Smoking, as London and her colleagues explain, often leads to mutations in lung cells, as well as to changes in the structure of the "packaging" of genes in the DNA of all cells of the body, which often change their activity, forcing cells to read them more or less often. The effect of such changes, which geneticists call "epigenetic", has not yet been fully studied.
Relatively recently, according to the authors of the article, molecular biologists have discovered that tobacco smoke can cause similar changes in embryos at the early stages of their development when they are grown in test tubes. The London group tried to find out whether such changes occur in the womb of mothers who do not give up smoking after conception.
To do this, scientists analyzed data on almost seven thousand pregnant women, a little more than a third of whom constantly or occasionally smoked while carrying a fetus. After the children were born, scientists collected blood samples from the mother and child, and studied how the "packaging" of their DNA was arranged.
As these observations showed, regular smoking during pregnancy led to large–scale changes in the structure of histones - proteins enveloping DNA. In total, scientists counted more than six thousand sites on their surface, the structure of which was changed in children growing up in the womb of smokers.
According to London, the genes that were located under these histone sites control the growth and functioning of the lungs, nervous system, predisposition to cancer and various congenital deformities of the mouth and pharynx. Almost all such epigenetic marks, as shown by DNA analysis of the older siblings of these children, continue to remain on their DNA even after several years of life.
Now scientists are analyzing the impact of each of these modifications of the "packaging" of DNA separately, trying to understand the role they can play in the development of health problems associated with smoking. This information will help to understand more precisely what kind of threat smoking poses to a mother and her children.
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01.04.2016