UK scientists successfully use DNA from three people to prevent rare genetic diseases in babies

This image from video provided by the Newcastle Fertility Centre shows a nuclear genome from an egg carrying a mitochondrial DNA mutation being inserted into an egg donated by an unaffected woman. (Photo Credit: AP)

In a landmark achievement in reproductive medicine, eight healthy babies have been born in the UK through an experimental technique that uses DNA from three individuals to prevent the transmission of rare mitochondrial diseases. The breakthrough, confirmed in a study published Wednesday in the New England Journal of Medicine, represents a critical step forward in helping families avoid passing on life-threatening genetic conditions.

The procedure, known as mitochondrial donation treatment (MDT), was carried out by scientists at Newcastle University in collaboration with Monash University in Australia. It involves replacing faulty mitochondria — the energy-producing components of cells — with healthy ones from a donor egg, while preserving the nuclear DNA from the parents.

How the Technique Works
Mitochondrial DNA is inherited exclusively from the mother and makes up less than 1% of a person’s total genetic material. However, mutations in this DNA can lead to devastating disorders, including muscle weakness, seizures, and multi-organ failure. The MDT process involves transferring the genetic material from a mother’s egg or embryo into a donor egg or embryo that contains healthy mitochondria, but has had its own nuclear DNA removed.

As a result, the child inherits nuclear DNA from both parents and mitochondrial DNA from the donor, effectively giving them genetic material from three people. Despite this, scientists emphasize that the donor’s contribution is minuscule and does not influence traits or identity.

A Regulatory and Scientific Milestone
The use of MDT was approved in the UK following a legal amendment in 2016, making it one of the few countries — along with Australia — to allow the procedure. In contrast, the United States still prohibits clinical use due to federal restrictions on heritable genetic modifications.

According to the study, 22 women underwent the procedure, resulting in eight healthy births. One additional patient remains pregnant. Each case was individually approved by the UK’s fertility regulator, the Human Fertilisation and Embryology Authority (HFEA). As of this month, 35 patients have received authorization.

Dr. Zev Williams, director of the Columbia University Fertility Center (unaffiliated with the study), hailed the findings as a “significant milestone,” stating that the ability to expand reproductive options offers new hope for affected families.

Concerns and Cautions
While the results are promising, experts caution that long-term monitoring is necessary. One of the newborns reportedly showed slightly higher levels of abnormal mitochondria than expected. Though not considered harmful, researchers say the child should be followed closely.

Critics also warn that the long-term consequences of mitochondrial replacement on future generations remain unknown. In the U.S., Congress has blocked FDA consideration of such techniques for over a decade, citing ethical concerns over genetic inheritance and embryo modification.

Hope for Families Affected by Mitochondrial Disease
For families impacted by mitochondrial disorders, this development offers a renewed sense of possibility. Liz Curtis, who lost her eight-month-old daughter Lily to mitochondrial disease in 2006, now runs The Lily Foundation to support research and raise awareness.

“Back then, we had no answers, no treatments, no hope,” Curtis said. “Now, for families facing the same diagnosis, this breakthrough gives them a chance at something we never had — a healthy future.”

(with inputs from AP)