Babies with the DNA of Three Different People Born in the U.K.

A medical first is changing the way we think about paternity and genealogy. The Human Fertilization and Embryology Authority in the United Kingdom has confirmed that several babies were born using an experimental in vitro fertilization (IVF) technique that combines the DNA of three different people. The approach is designed to prevent the children from inheriting rare genetic diseases. Fewer than five babies have ever been born this way in the U.K.

The women in question struggled to reproduce through traditional means because they have faulty mitochondria, the parts of the cell that drive movement and growth. The U.K. started regulating techniques to help these women reproduce via IVF in 2015 and the world’s first baby born with the DNA of three people was reported in the U.S. in 2016.

Women with faulty mitochondria often pass rare genetic disorders onto their children, including muscular dystrophy, epilepsy, heart problems, and cognitive deficiencies.

The process known as mitochondrial replacement therapy (MRT) involves taking genetic material from a mother with faulty mitochondria and putting it in an egg or embryo from a donor with healthy mitochondria that has the rest of its DNA removed.

Once the egg has been fertilized with sperm, it is transferred back into the womb of the mother. Thus, the resulting child will have the DNA of three different people, but the genetic material from the donated egg represents less than 1% of the child’s total identity.

But that small change in the child’s DNA can make all the difference when it comes to preventing rare genetic diseases. Mothers with a high risk of muscular dystrophy and other diseases can have children without worrying about passing them onto their kids.

“Mitochondrial donation treatment offers families with severe inherited mitochondrial illness the possibility of a healthy child,” said the Human Fertilization and Embryology Authority in a statement.

The University of Newcastle in collaboration with the Newcastle Fertility Center have become pioneers in this emerging technique. Robin Lovell-Badge, a stem cell expert at the Francis Crick Institute, a biomedical research center in London, who was not involved with the studies, says he will be watching the child’s future development.

“The Newcastle team involved in carrying out the procedures are cautious and will have wanted to include at least some follow-up data on the babies, while also protecting the privacy of the families,” Lovell-Badge explained. “This is a challenge in itself. It will be interesting to know how well the MRT technique worked at a practical level, whether the babies are free of mitochondrial disease, and whether there is any risk of them developing problems later in life or, if female, if their offspring are at risk of having the disease.”

Several babies have been born with the DNA of three people over the last few years, including one in Mexico in 2016, another in Ukraine in 2017, and one in Greece in 2019.

Some 32 patients in the U.K. have been approved for the procedure, according to the country’s leading IVF authority.

“The HFEA oversees a robust framework which ensures that mitochondrial donation is provided in a safe and ethical manner,” says Peter Thompson, chief executive of HFEA.

“All applications for treatment are assessed on an individual basis against the tests set out in the law and only after independent advice from experts. These are still early days for mitochondrial donation treatment and the HFEA continues to review clinical and scientific developments.”