Monozygotic twins are derived from an egg cell that divides to produce two embryos, but one twin may “disappear” during development and only one baby may be born. Now, new research may reveal whether your DNA started as an identical twin in the womb, even if your twins disappeared long before your birth. It suggests that.
The new study was published in the journal on Tuesday (September 28) Nature Communications, Researchers zoomed in on so-called Epigenetic Modifications found in twin DNA. The term “epigenetic” refers to the factor that allows a gene to be turned “on” or “off” without altering the underlying gene. DNA order. For example, small molecules called methyl groups can stick to specific genes like sticky notes, preventing cells from reading those genes and effectively turning them off.
According to a new study, the DNA of identical twins is adorned with a characteristic pattern of sticky methyl groups. The authors found that this pattern spans 834 genes and can be used to distinguish monozygotic twins from both dizygotic and non-twin twins. And in fact, based on these results, the team has developed a computer algorithm that can reliably identify identical twins based solely on the position of the methyl group throughout the DNA.
Theoretically, such a tool could also find someone who had a vanishing twin, but new research has not tested this idea.
In essence, this pattern of methyl groups is a type of “molecular scar” left over from early embryonic development in identical twins, a professor of pediatrics and genetics at Baylor Medical University, involved in a new study. Not Robert Waterland said. “The authors have discovered the epigenetic features of identical twins,” he said. This means twins derived from a single fertilized egg or zygote.
These methyl group-coated genes play a variety of roles in cell development, growth, and adhesion. That is, it helps the cells stick to each other. However, based on current studies, it is unclear how these methylation genes affect the growth, development, or health of identical twins in particular, Waterland said.
In investigating these wounds in early development, the author wanted to better understand why the same twins first occurred. Scientists know that zygotes divide at certain points of development, but it was a mystery as to why division sometimes occurs. “”[The study] Jenny van Dongen, an assistant professor and lead author of the Department of Biological Psychology at the Free University of Amsterdam (VU), said:
An estimated 12% of human pregnancies begin as multiple pregnancies, but less than 2% are carried to maturity. So, according to the 1990 report, the rest are so-called vanishing twins. International Journal of Fertility and Infertility.. Overall, sibling twins are generally more common than identical twins when both twins reach maturity.
Evidence suggests that Genetics Affects the chances of a mother giving birth to dizygotic twins. This happens when two eggs are fertilized at the same time. For example, studies show that sibling twins may be carried out in the family, and genes involved in hyperovulation appear to be working, Van Dongen said. By comparison, the prevalence of identical twins is fairly consistent around the world, occurring approximately 3-4 times for every 1,000 live births. This suggests that genetics does not cause this phenomenon. The question is what to do.
“It’s really a mystery of developmental biology,” said Dorret Boomsma, a senior author and professor of biological psychology at VU Amsterdam.
The team wondered if this mysterious solution could be encoded by the methyl groups that decorate human DNA, as it helps the molecule control embryogenesis at its very early stages. And thanks to a special protein called methyltransferase, the methyl groups added to the DNA under development are copied as the cell continues to divide. In other words, you can stick to adulthood.
In a new study, the team pulled epigenetic data from six large cohorts of twins, for a total of over 6,000 people. The cohort included both identical and dizygotic twins, as well as non-twin families of these individuals. By including dizygotic twins, the team was able to see if the epigenetic patterns found in identical twins were actually unique to them and not common to all types of twins.
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Most of the DNA methylation data blood Although samples were collected from adults, one dataset consisted of cheek swab samples from children. And across all samples, the team found the same different methylation patterns in the same twin DNA.
“The fact that you can see the same thing in those cells is encouraging,” Waterland said. This indicates that the pattern is not unique to any particular type of cell. This means that clear methylation took place very early in development before special tissues such as: heart Also lung, Has begun to form. When a methyl group attaches to DNA at this stage, the methyltransferase passes the molecule to all subsequent daughter cells, regardless of the final cell type.
Some datasets contained DNA samples collected at multiple time points, allowing the team to reaffirm how stable these methylation patterns were over the years. “They found that these methylation states were very stable in individuals,” Waterland said.
“It looks like something is happening very early in development, which remains written in the methylation patterns of the various cell types in our body,” Van Dongen said. “It remains archived in our cells.” However, for now, what exact effects of these methyl groups have on gene expression (of the “on” or “off” of the gene). It’s unclear if the switch), or methylation pattern, represents the cause, effect, or by-product of the same twin, she understands.
“Functional studies are really needed to really understand the exact steps taken in the early stages of embryogenesis that lead to the formation of identical twins,” Van Dongen said. Mentioned studies that investigated whether it affected. The team plans to carry out such studies using animal models of laboratory dishes and human cells.They may also use a human embryo model Known as Blastoid..
In the future, the team will also be able to investigate larger examples of epigenetic modifications to the genome to see if the methylation pattern exceeds the 800 odd genes that have already been identified. Mr Rand said. The new study covered hundreds of thousands of potential methyl group attachment points, but he said there was much more to investigate.
Originally published in Live Science.
Did you share your womb with the “vanishing twin”? The answer may be in your DNA.
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