Babies with DNA from three people: a scientific breakthrough that revolutionizes the world

The medical world is in turmoil this week after it was revealed that eight babies were born in the United Kingdom free of mitochondrial diseases thanks to an assisted reproduction technique that combines genetic material from three people. Although currently permitted only in this country, it promises to become a path forward in the coming decades.

The procedure, developed by British scientists and legalized a decade ago, was documented by BBC Mundo in a report that includes the initial clinical results and the reactions of beneficiary families. It explains how the method, known as "mitochondrial donation," seeks to prevent mothers from transmitting devastating genetic conditions that affect the body's energy metabolism to their children.

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As they explained, mitochondria, tiny structures present in almost all human cells, are responsible for producing the energy needed for the body to function. When these structures fail, the consequences can be lethal, leading to brain damage, organ failure, muscle weakness, and death in the first days of life.

Approximately one in every 5,000 babies is born with a mitochondrial disease , and in these cases, the cause is usually maternal, since mitochondria are inherited exclusively from the mother. Therefore, the British technique seeks to break this cycle by fertilizing an egg from the mother and one from a donor with the father's sperm. The pronuclei (containers of the parents' nuclear DNA) are then removed and inserted into the donated egg, which retains its healthy mitochondria.

The result is an embryo with 99.9% of the parents' DNA and 0.1% of the donor's genetic material, enough to ensure the healthy functioning of the mitochondria. This minimal genetic intervention has allowed eight children—four girls and four boys, including a pair of twins—to be born without signs of disease, and another pregnancy is underway.

The BBC Mundo report includes anonymous testimonies from families who underwent the procedure at the Newcastle Fertility Centre. One mother added, "After years of uncertainty, this treatment gave us hope and then gave us our baby." Another mother added, "The emotional burden has disappeared, and in its place is hope, joy, and deep gratitude."

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Although the procedure has been successful, scientific doubts persist about its scope, since in five of the cases analyzed, defective mitochondria were not detected, but in three, between 5% and 20% of damaged genetic material was found. Despite being well below the threshold that triggers the disease (80%), the researchers emphasize the need for continued long-term monitoring. One of the babies had mild epilepsy (now overcome) and another had a heart problem that is being successfully treated.

A debate that goes to the ethical

From an ethical standpoint, the technique has also generated debate, since mitochondria have their own DNA, girls born through this procedure will pass this modification on to their offspring, implying a permanent change in the human genetic line and, for some critics, opening the door to so-called "designer babies."

Even so, the United Kingdom is the first country in the world to legalize this technique after a parliamentary vote in 2015. “Only here could it happen: we had world-class science, an appropriate legal framework, and the support of the public health system,” Professor Doug Turnbull of Newcastle University told the British media.

Finally, the Lily Foundation, an organization dedicated to supporting families affected by mitochondrial diseases, celebrated the news, saying, "After years of waiting, we now know that eight babies have been born using this technique, and none show any signs of disease. This is the first real hope of breaking the cycle of this inherited condition."