- Eight babies have been born in the United Kingdom after undergoing pronuclear transfer, a technique that reduces the risk of inherited mitochondrial diseases.
- The procedure uses genetic material from three people and replaces the mother's defective mitochondria with those from a healthy donor.
- The legality and ethical impact of this technique are controversial, as it is not yet regulated in countries like Spain.
- Experts emphasize the need for long-term follow-up to understand the potential effects and actual effectiveness of the procedure.
Un unprecedented scientific progress has allowed eight babies are born free of hereditary diseases of mitochondrial origin in the United KingdomThis new reality has been achieved thanks to a technique applied by the University of Newcastle and published in the journal New England Journal of MedicineThe method has brought renewed hope to families with mitochondrial DNA mutations, genetic conditions that, until now, had no effective treatment.
Mitochondrial donationKnown as “three-parent technique”, consists in replacing defective mitochondria from the mother's egg with those from a healthy donor, without altering the nuclear DNA of the parents. In this way, The resulting baby inherits most of its genetic information from its parents, but a small fraction comes from the donor woman, which prevents the transmission of mitochondrial diseases.
What does pro-nuclear transfer entail?
The procedure, legalized in the United Kingdom since 2015, has been used so far in Twenty-two women with mitochondrial mutations, resulting in eight confirmed births and one pregnancy still in progress. The technique is performed after in vitro fertilization of the eggs from the mother and the donor with the father's sperm. The parents' nuclear genetic material is then transferred into a donated egg that has been stripped of its nucleus, preserving the donor's healthy mitochondria.
The result is an embryo with nuclear DNA from the parents and mitochondrial DNA almost exclusively from the donor.This prevents maternal transmission of diseases that seriously affect energy-demanding tissues such as the heart, brain, or muscles. Although male parents can be affected by these diseases, only women can transmit them to their children, since mitochondria are only inherited through their mothers.
In the eight babies born, all have shown a healthy development, exceeding the expected milestones for their ageIn six cases, the Pathogenic mitochondrial mutations were reduced by more than 95%, and in the remaining two, between 77% and 88%. Some of the babies had minor problems unrelated to the technique, and regular medical follow-up is performed to monitor their progress.
Why is this technique relevant?
Pro-nuclear transfer represents a revolutionary option For families at high risk of transmitting incurable diseases through traditional methods. The technique offers the possibility of having biologically unique offspring without the fear of inheriting mitochondrial mutations. The process does not mean the total elimination of risk, but it drastically reduces it., moving mutational levels away from the thresholds that cause clinical disease.
Currently, around One in every 5.000 newborns suffers from some mitochondrial diseaseThese pathologies can be devastating, affecting cellular energy and causing damage to vital organs. The lack of a cure has prompted the search for alternatives such as in vitro fertilization with preimplantation genetic diagnosis or pro-nuclear transfer.
However, the procedure has limitations. During nuclear transplantation, a small number of the mother's mitochondria may accompany the genetic material and persist in the embryo. Even so, in documented cases, the presence of pathogenic mitochondria never exceeded 20%, well below the dangerous level of 80% that causes disease.
Advantages, risks and ethical issues
Pronuclear transfer allows families to maintain the genetic link with both parents., a key difference from traditional egg donation, where maternal nuclear DNA is lost. The alternative therefore offers an intermediate path between conventional conception and complete donation, which eliminates the risk but modifies the genetic relationship.
Experts stress the need for comprehensive counseling for families who opt for this procedure, since the risk reduction does not imply the absolute eradication of the disease. Furthermore, There is a possibility that in some cases the fraction of maternal mitochondrial DNA may increase during development, although initial data indicate that it tends to stabilize after birth.
Various voices within the scientific community insist on continuing with the long-term follow-up of children born using this technique, extending it until at least the age of five, to ensure that they do not manifest unexpected adverse effects related to the combination of nuclear and mitochondrial DNA from different people.
The pioneering use of pro-nuclear transfer has also generated ethical and legal debates. In the United Kingdom, after a long process of public consultations and scientific reviews, The technique was authorized, but in countries like Spain the assisted reproduction law does not contemplate it., so it is neither explicitly prohibited nor permitted. Experts consider It is important to address the legal vacuum to prevent the emergence of “reproductive tourism” and ensure the safety and ethics of the procedures.
The future of technology
The success of pronuclear transfer in the birth of healthy babies opens a path of hope for families affected by mitochondrial diseases and consolidates the United Kingdom's role as a leader in the application of advanced assisted reproduction techniques. Other countries are closely monitoring these results, which could accelerate the international regulation and adoption of mitochondrial donation.
The First experiences show a remarkable success rate, close to 36%., and confirm that the technique allows the transmission of pathological mutations to be minimized, although without eliminating the risk completely. The scientific community agrees that importance of continuing to research to perfect the procedure, improve case selection and resolve any ethical and medical concerns that may arise.
With the pro-nuclear transfer, Reproductive medicine takes a significant leap in genetic prevention, offering the possibility of having children free of previously incurable ailments for families with a high hereditary risk. Meanwhile, researchers and doctors continue to monitor children born using this technique to ensure their health, refine protocols, and assess the true scope of this revolutionary advance.
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