According to a recent scientific study, the genome of identical twins diverges at a rate of 5 mutations at a very early stage, and this provides a completely different view of the prevailing scientific views about this type of twins.
In a report published in the French newspaper "Le Monde", writer Florence Rossier says that the question of the ideal congruence between twins has been questioned from a scientific point of view, and this is confirmed by a study published on January 7 in the journal Nature Genetics ( Nature Genetics).
The study was supervised by Professor Carrie Stephanson from Reykjavik University, a pioneer in the use of genetics to understand differences in human genome sequences, and founder of the biopharmaceutical company "Decode Genetics".
Differences between monozygotic twins
Before going into detailing the study, let's review some terms:
Zygote is the fertilized egg that results from the fertilization of the sperm from the male to the egg from the female.
A true twin "identical twin" is called the term "onozygotic", meaning that there is one zygote, then it separated into a zygote, each one that formed a fetus.
This is what happens in a true twin.
An unreal twin, which is not identical, is called "dizygotic" twins. It is a twin that results from the fertilization of two separate eggs from two different sperm during the same pregnancy.
Monozygotic Triplets, meaning that the zygote split into three zygotes, giving 3 identical twins.
Back to study
The researchers decoded the genomes of 381 pairs of identical twins, in addition to two pairs of monozygotic triplets, and analyzed 3 types of tissues (blood, adipose tissue, and oral epithelial tissue).
Tissue analysis revealed 23,653 mutations for each individual, and the rate of mutations that distinguished one twin from the other was 14 mutations, but with great variation between couples, as the number of mutations in 30 pairs reached more than 100 mutations, while there was no characteristic mutation. At another 30 pairs.
The results showed an average of 5.2 mutations during a very early stage of fetal development.
It is already known that there are some rare mutations that distinguish monozygotic twins, says Joerg Toast, a researcher at the French National Center for Human Genome Research, but "this is the first time that a study has monitored the number of these mutations in a large sample."
In the Icelandic study, researchers decoded the genome of the spouses and children of 181 pairs of twins, and discovered that in about 15% of cases, one of the twins passed on to his offspring mutations of his own that he did not share with his twin.
According to the author, this study helps to uncover more secrets about the nature of genetic and environmental factors affecting the lives of identical twins, which researchers have been interested in for a long time.