Scientists have long used the study of identical twins to examine the effects of nature on food, as the accepted view has been that because they share the same genes, physical or behavioral differences between these brothers must be external influences.
Identical twins come from a single fertilized egg or zygote.
In any embryo, cell division can cause mutations, but this type of genetic difference had not been previously measured between identical twins.
Scientists sequenced the genome of 387 pairs of identical twins and their parents, spouses and children to track mutational divergence. The authors found that twins differed by 5.2 early mutations in development, on average.
In approximately 15% of twin pairs, one sibling carried a large number of these mutations that the other twin did not have.
A genetic mutation is an error or change in DNA. A mutation occurs when the sequence of the genetic code is broken or changed in some way. While most mutations are harmless, some can be serious and can cause diseases such as cancer. Mutations can also affect physical attributes such as hair color.
This is not the first study to suggest differences between so-called identical twins. An article published in The American Journal of Human Genetics in 2008 revealed some genetic differences between his siblings. However, the new research goes beyond including the DNA of the extended family.
Genetic differences
Some of the research topics revealed striking differences, study co-author Kari Stefansson told CNN.
The implications of this are significant, according to Stefansson, as the research led the team to conclude that the role of genetic factors “in shaping the differences observed between monozygotic twins” has been “underestimated.”
He acknowledged that both science and society in general are fascinated by identical twins, adding, “There is something magical about the connection between identical twins.”
His team’s research, however, is more about what divides them than unites them.
“Imagine that you have identical identical twins. If one of them develops autism, the classic interpretation is that it depends on environmental factors. But our work shows that before we conclude that it is caused by the environment, you have to sequence the genome of the twins to know what could explain autism, ”Stefansson said.
He told CNN that the “mutational divergence” could explain a number of “devastating childhood illnesses,” such as severe epilepsy and various metabolic disorders.
“It’s absolutely amazing that a percentage of these horrible early childhood syndromes come down to genome mutations,” he said.
“This is an extraordinary, exciting and insightful effort to identify the first cellular mechanisms that explain the genetic differences between MZ (monozygotic) twins,” said Nancy Segal, author and professor of psychology who studies twins at the University California State (Fullerton) and that was not it. involved in the research.
“It is well known that MZ twins do not have a perfect resemblance and that some differences may reflect genetic differences. The present study provides new information on the source of differences between MZ twins,” said Segal, who is also director of Center of CSU Twin Studies.
The research “did not negate environmental factors in initial and subsequent development,” he added, but showed that “some twin models underestimate genetic effects and require revision.”
Segal Segal, the study also raised questions about how the findings should be applied, such as whether prenatal intervention is needed to correct certain genetic disorders.
“There are a lot of tempting questions that this extraordinary study raises,” he said.