So-called “three parent babies” may be returning to labs in the United States.

But it won’t happen this year and the experiments will probably be limited to male embryos only.

A recent advisory report concludes that clinical research into mitochondrial therapy procedures on human embryos is “ethically permissible” as long as it meets several conditions.

Three Parent

The U.S. Food and Drug Administration (FDA) requested the report. It was written by a committee made up of members of the National Academies of Sciences, Engineering, and Medicine along with the Institute of Medicine (IOM).

It recommends limiting initial research “to women who are at risk of transmitting a severe mitochondrial genetic disease that could lead to a child’s early death or substantial impairment.”

Due to budget constraints, FDA officials aren’t expected to look much deeper into the report until next year.

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Limiting Research to Baby Boys

The procedure, also known as mitochondrial replacement techniques (MRT), allows damaged mitochondria to be removed from a mother’s egg and replaced with healthy mitochondria from a donor egg.

The result is a designer embryo formed by three parents.

Before it was banned a decade ago in the U.S., several women conceived healthy children using this method.

Research on this technique was given the go-ahead last year in the United Kingdom.

The ailments caused by damaged mitochondria include developmental delays, heart problems, muscle weakness, and vision loss. The therapy can modify an egg or a fertilized egg.

The report recommends that research on therapy be limited to male embryos because one in 5,000 people have a mutation in the mitochondria’s DNA derived from their mothers.

This limitation would prevent the male embryos from passing along the defect to future generations.

Jeffrey Kahn, PhD, who chairs the committee that compiled the report, said the next step is for the FDA to decide what to do with the recommendations and see if clinical investigations are allowed.

Kahn is a professor of bioethics and policy and deputy director for policy and administration at the Johns Hopkins Berman Institute of Bioethics.

He told Healthline the report is an “ongoing discussion related to the new reproductive technology” and that it provides good information for yet-to-be-developed technologies.  

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Reactions Vary on Report

Some industry leaders are already weighing in on what all this could mean.

I. Glenn Cohen, JD, the faculty director at Harvard Law School’s Petrie-Flom Center, published a blog post about the report. He described the recommendations that MRT be limited to the transfer of male embryos as “clever and interesting.”

He said it could have some negative ramifications, such as requiring that female embryos be discarded or frozen. That move could anger some religious conservatives.

It would also differ from what is permitted in the U.S. compared to the U.K., he added, where a restriction doesn’t exist.

“The committee is to be commended for accurately describing the pursuit of this research as a response to a ‘desire’ on the part of some women to have genetically related children without mitochondrial disease,” Françoise Baylis, PhD, a professor at Dalhousie University, said in a statement. “Too often the ‘desire’ of prospective parents for genetic relatedness is inappropriately described as a ‘need,’ placing focus on reproductive rights instead of parental responsibilities. It is important not to overvalue genetic relatedness within families.”

Overall, Baylis said, the guiding principles for the oversight of research on the therapy are “generally sound.”

She added that they do not, however, include a “principle of ‘care and concern for egg providers’ who assume the risk of potential harm for no potential benefit other than perhaps financial compensation which, for some, exposes them to the harms of either commodification or exploitation.”

Dr. Bruce Cohen, director of the NeuroDevelopmental Science Center and pediatric neurology at Akron Children’s Hospital, said in comments that he was not directly involved in research on MRT, but he suspects groups that do so are reviewing the recommendations carefully.

“My hope is that we will have clinical trial protocols up for review in a few months,” he wrote.

He added that he believes in taking a “multi-pronged approach to treat mitochondrial disease with mitochondrial replacement being one, medications being another, and genetic modification like CRISPR [another genome-editing technology] being yet another option for treatment.”

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