DNA, epigenetics and egg donation
A few days ago, we read a post on the Instagram profile @lavidamadre.es that made us think about our patients: "To be a mother, you have to share love, not DNA." The mistaken belief that DNA differs greatly from one human being to another is a major concern for them when they are offered treatment with gamete donation.
DNA
Scientific progress has shown that we are almost identical when we compare our DNA. However, many people believe that human DNA is only 5 or 10% similar. This misconception stems from the fact that, before the results of the Human Genome ProjectWe used to think that DNA between different human beings had very little similarity. We thought that DNA had large areas that were completely different from one human to another; these areas were what each of us called "my DNA." We thought that each of us had an "enormous" genetic heritage and we were excited to pass it on to our children.
The Human Genome Project allowed us to learn the complete sequence of our 46 chromosomes. Once several genomes had been sequenced, we were able to compare the DNA sequences of different people, and to everyone's surprise, it was found that We are 99,9% identical at the DNA levelThis finding surprised many people who intuitively thought that our differences at the DNA level were much greater than an "insignificant" 0,1%.
The biggest surprise came when it was observed that the similarity between the human genome and that of the chimpanzee (Troglodytes bread) reaches 98,77% and that the similarity with the DNA of the mouse is 88%, without us having a significant physical resemblance to these or other animals.
The next question would be whether a mere 0,1% difference in DNA could explain all the phenotypic differences we observe between different human beings. The answer is no. In addition to that 0,1% difference in DNA sequence, it's also important to consider that epigenetics plays a significant role in our vital expressions, both physical and metabolic.
epigenetics
Epigenetics is defined as heritable changes that do not involve the DNA sequence but, by altering the structure and condensation of chromatin, directly affect gene expression and phenotype.
Epigenetics is responsible for our offspring being unable to use a "perfect" gene in their DNA sequence due to an epimutation inherited from their mother during pregnancy. In fact, there is no difference in phenotype between having a mutation and an epimutation in a gene.
Egg Donation
Therefore, a couple who receive a donated gameteAn egg, for example, receives a cell capable of being fertilized and that has DNA that is 99,9% identical to that of any woman.An egg contains approximately 25.000 genes, virtually identical in all women. The key lies in selecting which of these genes will be expressed—crucial decisions that begin during pregnancy and are unique to the pregnant mother.
Of course, after birth, epigenetics continues its course and Our children end up being a mixture of epigenetics, education, experiences, and the love we have given them throughout our life together. They grow as people and we as parents, in love with our children, each one of whom is special and unique, despite having DNA that is 99,9% identical to that of everyone else.