Around one couple in four suffer from fertility problems; and, among the main causes, is the delay of motherhood. Assisted reproductive techniques have come a long way in recent decades, but we must be aware that they are not a panacea: in fact, women under 35 currently have only a 32.2% chance of becoming pregnant after a pregnancy. in vitro fertilization cycle (IVF) . And those probabilities decrease considerably with age: the percentage is 27.7% in women between 35 and 37 years old and 20.8% in those who are 38 or 39.
Now, a team of scientists from the Francis Crick Institute in London has discovered a “master gene” that seems crucial to achieving pregnancy, a finding that could open the door to improving the results obtained by these IVF treatments in the future . Likewise, this British study, published in the journal Nature , represents a breakthrough in understanding infertility and why so many attempts at pregnancy do not progress properly and end in miscarriage.
Research has shown for the first time that gene editing can be used in the study of the genetic behavior of human embryos in their first days of life . In this way, the team discovered that the POU5F1 gene, which produces a protein called OCT4, is crucial for a viable pregnancy.
This research is not without controversy despite having been authorized by the Human Fertilization and Embryology Authority, since it is based on the use of a technique similar to that used in so-called “designer babies”, those whose genetic inheritance has been selected using various reproductive technologies in order to achieve optimal recombination of the genetic material of their parents. As this type of experimentation requires the use of human embryos, not everyone welcomes it due to the ethical implications that it entails. The new technology, called CRISPR-Cas9, seeks to achieve, by editing DNA (cutting the defective and replacing it with good), genetic repair . This technique in medicine is considered the greatest scientific advance of the year 2015 and its main objective is to correct mutations inherited from the father, the mother or both and free babies from serious congenital diseases.
In any case, Francis Crick’s team ensures that their work only aims to understand the early stages of conception . And indeed, by the terms of this research, modified human embryos must be destroyed after fourteen days.
Future research
During this study, a total of 41 human embryos donated by IVF patients were analyzed. To do this, the researchers used the CRISPR / Cas9 technique to make precise cuts in the DNA and, thus, block the action of the POU5F1 gene and prevent it from producing the OCT4 protein . By deactivating it, they found that it seemed necessary for an embryo to end up becoming a blastocyst, a tiny ball made up of approximately 200 cells that arises a week after conception has occurred and that marks a key point in the development of the embryo.
The chances of this embryo implanting in the maternal uterus depends on whether it successfully reaches the blastocyst stage: and, according to this British research, less than a fifth of those embryos in which the OCT4 protein was deactivated succeeded .
Dr. Kathy Niakan is one of the scientists who has led this study, and defends that “one way to find out what a gene does in the developing embryo is to see what happens when said gene does not work .” “Now we have shown an efficient way to do it, and we hope that other scientists will use it to discover the role that other genes play,” he adds.
It also points to the possible improvement that this discovery could lead to in assisted reproduction success rates. “If we knew which key genes embryos need to develop successfully, we could improve IVF treatments and understand some of the causes of pregnancy failure,” he concludes.
Reference:
Norah ME Fogarty. Genome editing reveals a role for OCT4 in human embryogenesis. Nature (2017) Doi: 10.1038 / nature24033
