Discovering the first mutations in human life, what are they?

The most ancient mutations were explained by researchers at the Sanger Institute and their collaborators. The oldest human mutations were observed by researchers in this institute, and the genes were analyzed from adult cells and scientists were able to look back to reveal and learn how each embryo developed.

This study was published in the newspaper (Al-Nature), the study showed that, starting from the two-cell stage in the human embryo, one of these two cells becomes more dominant than the other and later forms a higher proportion of the adult body.

And this question remained for a long time for researchers: What happened during the very early evolution of humans? It was not possible to study this directly.

Now the researchers analyzed the complete genome sequences in blood samples collected from 279 people with breast cancer and discovered the 63 mutations that occurred very early during the embryonic development of these people, and once they were identified, the researchers used the mutations from the first, second, and third division of the fertilized egg to calculate the proportion of adult cells that resulted. From each of the first two cells in the fetus.

And they found that these first two cells contribute differently to building the body as a whole. One of the cells gives up to 70% of the tissues of the body, while the other contributes a slight up to 30% of the tissues: this deviant contribution continues in some cells until the second and third generation.

This is when the normal blood cells of cancer patients were mainly diagnosed and then the mutations in cancer samples that were surgically removed during treatment were studied, unlike normal tissues, which consist of multiple copies of somatic cells, cancer cells develop from a single mutant cell, so all proposed fetal mutations must be They can be found in all cancer cells or not in any of them, and by using these carcinogenic samples, researchers were able to validate that the mutations arose during embryonic development.

Dr. Inigo Martincorena of the Sanger Institute says after neutralizing the mutations, we were able to use statistical analysis to understand cell dynamics during fetal development and to determine the relative contribution of first embryonic cells to adult blood cell aggregation, and found one dominant cell that resulted in 70% of blood cells and one small cell secondary and we did It also tracks breast cells and lymphocytes, and the results indicate that the dominant cells also contribute to these tissues at a similar level to other cells, which opens an unprecedented window in the early stages of human development.

During the study, researchers were able to measure the rate of mutation during early human development from the first time to the next three generations of dividing cells.

Previous researchers estimated that there was only one mutation in each cell division, but this study measured three mutations for every cell duplication in every daughter cell.

Mutations occur during embryonic development by two processes known as mutational signatures 1 and 5. These mutations are distributed somewhat randomly within the gene.

The vast majority will not affect the embryonic development of mutations that occur in the important gene that lead to diseases such as developmental disorders.

This is an important step forward in expanding the range of biological ideas that can be extracted using gene sequences and mutations, says Professor Mike Stratton, the paper's lead author and director at the Sanger Institute. Basically, mutations are archaeological sites that lead us to understand the embryonic development occurring in our adult tissues, so if we want to. Finding it and its interpretation We can better understand human embryology and this is only an early look into the science of human evolution, hoping more for it in the future.