The U.K. has recently become the first country in the world to legalize mitochondrial transfer, which has left people wondering: why not the U.S.? Mitochondrial transfer is also known as three-person in vitro fertilization.

The techniques of this fertilization have the potential to prevent mitochondrial disease, which is a group of disorders such as deafness, diabetes, epilepsy, and other more life-threatening disorders, in the offspring.

Doctors in Britain, who are looking to perform this procedure, must first apply for permission from the Human Fertilization Embryo Authority (HFEA). It is likely that the HFEA will require more safety and effective data on mitochondrial transfer before giving out any licenses.

So why hasn’t the U.S. passed a law that allows three-person in vitro fertilization? It was actually in the U.S. that the first mitochondrial replacement took place yet, for somewhat unknown reasons, some people are concerned that this type of IVF might lead to widespread genetic engineering.

Mitochondrial replacement IVF does one simple thing: replace a single strand of the mother’s DNA with third-party mitochondria from a healthy egg donor, as mitochondrial DNA is passed down from the maternal line. Traits such as hair and eye color, on the other hand, are controlled by DNA in the cell nucleus. Mitochondrial IVF won’t start a eugenic epidemic but could save thousands of lives and prevent serious suffering

In 2001, the FDA banned an assisted reproduction procedure similar to mitochondrial replacement IVF, cytoplasmic transfer, in which donor egg cytoplasm is injected into an egg with mutated mitochondria. The agency had concerns about chromosomal abnormalities with three people’s DNA in one embryo and a need for oversight when transferring genetic material outside of egg and sperm fertilization.

FDA spokesperson Tara Goodin has said, “The FDA has not made any decision regarding clinical trials of mitochondrial manipulation technology.”

Lehigh University’s Dena Davis, a bioethics professor, states that debates over mitochondrial replacement are often the result of confusion.

“This is only an ethical problem if one has the misguided idea that babies and children are created by only two parents,” Davis says. “But, babies created through the use of a gestational surrogate mother already have three parents, because nine months’ pregnancy surely leaves its mark on an infant. And babies who are wet nursed, which used to be a common practice, received important nurturing and nutrients from a third parent.”

Even though this technology has the potential to eradicate devastating genetic conditions, until the FDA is satisfied that any potential risk is worth the trade-off, there is no indications that the U.S. will be seeing mitochondrial transfers legalized anytime soon.