A medical revolution has just taken a decisive step. For the first time, eight newborns have escaped potentially fatal mitochondrial diseases thanks to a revolutionary technique: mitochondrial gift. This advance, the fruit of forty years of fierce research, gives hope to families condemned to transmit incurable pathologies from generation to generation.
When cellular energy power plants malfunction
The mitochondria, these tiny organelles nicknamed “Cell Energy Centrals” have their own genetic heritage distinct from that contained in the cell nucleus. Unlike nuclear DNA inherited from both parents, mitochondrial DNA is transmitted exclusively by the mother. Problem: when this maternal DNA has changes, the consequences can be dramatic.
Hereditary mitochondrial diseases strike approximately one in 5,000. Their impact varies considerably depending on the severity of mutations. Some patients are developing simple chronic fatigue, others undergo convulsions, progressive muscle, severe heart problems or development delays. In the most tragic cases, these pathologies cause death in the first days of life.
The transmission of these diseases has a particularly cruel character: its unpredictability. The same mother can wear eggs with variable mutational loads. Some contain little or no harmful mutations, others only defaulting mitochondrial DNA. This genetic lottery places parents in the face of a heartbreaking choice: to design hoping to obtain a healthy child, or to give up their parental project.
A technological solution to the limits of chance
Faced with this dead end, scientists have developed a revolutionary approach: pronuclear transfer. This complex technique is carried out in several meticulous steps. The medical team first fertilizes the ovum of the future mother by intracytoplasmic injection of sperm. Once the fertilization is successful, the researchers extract the kernel from this embryo to transplant it into a donor egg previously emptied of its own nucleus.
The receiver egg comes from a donor whose mitochondria have been carefully checked and deemed exempt from pathogenic mutations. The result of this technical feat: an embryo bearing the nuclear DNA of biological parents but benefiting from healthy mitochondria from the donor.
This approach represents the culmination of decades of effort. The first experiments on mice date from the 1980s, but it was not until 2015 that British pioneer legislation authorizes tests on viable human embryos. Since then, scientists have gradually refined their technique, overcoming the many technical obstacles encountered.
Credit: ISTOCK
The mitochondria (photo) contain a unique DNA, but a mutation of this DNA can cause incurable diseases. A new clinical trial seeks to reduce the risk of these diseases. Credits :: Inkoly/Istock
Promising results under close surveillance
The clinical trial recently published in the prestigious New England Journal of Medicine demonstrates the effectiveness of this approach. Twenty-two patients with too high mutational charges to benefit from conventional embryonic selection techniques participated in the study. Eight of them fell pregnant and gave birth to perfectly healthy babies.
These children, currently closely followed by medical teams, achieve all their development objectives. Their surveillance will continue for years, researchers providing in particular an in -depth assessment at the age of five to detect possible subtle developmental disorders.
Nevertheless, the technique does not offer an absolute guarantee. During nuclear transfer, tiny quantities of maternal mitochondrial DNA can accompany the transplanted nucleus. Some babies thus have detectable traces of this potentially problematic DNA, although insufficient quantities to trigger a disease. This limitation highlights the importance of continuous monitoring and constant improvement in technique.
A glow of hope for the families concerned
This scientific advance radically transforms the prospects of affected families. As a mother participating in the study expresses: this technique dispelled the feeling of fear that weighed on their parental project. For researchers involved, notably Mary Herbert of Monash University and Bobby McFarland from Newcastle University, this success crown years of hard efforts.
Mitochondrial donation now opens a therapeutic path where only a medical deadlock there was before. Although the technique still requires improvements, it represents a concrete hope for families faced with the transmission of hereditary mitochondrial diseases.
