This baby has DNA from 2 parents plus 1 other woman

• A UK baby is one of a few born through a procedure using DNA from three people.
• The procedure uses mitochondria from a donor's egg to help prevent mitochondrial diseases.

A newborn baby is one of only a few worldwide to have DNA from three different people: the mom, dad, and a female donor.

The baby, born in the UK, was conceived through a novel type of in vitro fertilization (IVF) intended to prevent inherited, and often fatal, mitochondrial diseases, the BBC reported.

While carriers of these mutations can have children through adoption or egg donation, the procedure can allow them to carry and deliver babies with their own DNA.

The donor is not considered a "parent." That is in part because her donation — mitochondria — won't influence the child's personality, appearance, or other characteristics, professor Doug Turnbull, head of the center in Newcastle that pioneered the research, previously told the BBC.

In fact, she only accounts for 0.1% of the baby's DNA.

A groundbreaking solution to a medical mystery

Mitochondrial disease is something of a mystery in medicine.

There are no cures or "highly effective" treatments for the conditions, which research shows can be deadly within days of birth. The BBC previously wrote about a woman who lost all seven children due to mitochondrial disease.

Mitochondria are the small compartments in cells mainly used to produce energy.

When they don't function right, they can lead to health issues, including seizures, heart problems, vision and hearing issues, impaired kidney function, and more.

How it works

In an attempt to prevent these diseases, Turnbull and colleagues developed a technique to use mitochondria from a healthy donor's egg.

The process, called mitochondrial donation treatment or mitochondrial replacement therapy, can involve swapping out the donor egg's nucleus (which contains its genetic material) for the mom's nucleus before fertilizing it with the dad's sperm. Or, a similar process can occur but with an already-fertilized embryo instead of an egg.

Either way, the healthy mitochondria remain intact while the vast majority of baby's genetic information comes from the parents. The resulting embryo is then implanted into the mom.

Because mitochondria are passed down from the mother, the donor must be female. The procedure has been controversial since it can involve destroying embryos and is considered genetic modification.

There are a few of these unique children — but information on them is highly protected

The first baby born this way was delivered in the US in 2016 to a Jordanian family. But so few children have been conceived this way, and much of the information on them is protected, so it's not entirely clear yet how well they fare.

Some babies, for example, may still go on to develop diseases since it's inevitable that some of the mom's mitochondria still gets passed to them, research has shown.

"Long-term follow-up of the children born is essential," Dagan Wells, a professor of reproductive genetics at the University of Oxford who was involved in the research, told the Guardian.