Mitochondrial Replacement 'Ethically Permissible,' IOM Says

Lara C. Pullen, PhD

February 09, 2016

A new consensus report issued by the Institute of Medicine finds that research into mitochondrial replacement techniques (MRTs), where an embryo has genetic information from three people, is "ethically permissible," and should be allowed to move forward under limited conditions.

The US Food and Drug Administration (FDA) requested the report on the ethical, social, and policy considerations related to MRT to advise its decision whether to sanction such research in the United States.

If MRT is effective, it would allow women with mitochondrial DNA (mtDNA) disease to have genetically related children without passing on their mtDNA diseases. The technology represents a unique opportunity for a small group of patients, explained Marcelle Cedars, MD, from the University of California, San Francisco, in an interview with Medscape Medical News.

Dr Cedars suggested that physicians understand the basis for MRT so that "they don't perpetuate this sense of sort-of three-parent reproduction."

For the women with mitochondrial disease, this the only path for them to have their own genetic children. Dr Cedars explained that, as a reproductive endocrinologist, she sees first-hand the primal instinct to have a family. MRT may extend the opportunity to reproduce to yet another group of people, while at the same time improving human health.

MRT Is Unique

In effect, MRT represents the culmination of the transition from bench research to primate studies to improving human health. It is a unique approach to genetic engineering.

The Institute of Medicine (IOM) committee clearly distinguished between modification of mtDNA and modification of nuclear DNA. MRT does not involve targeted editing of the nuclear genome. In addition, MRT will be limited to women with mtDNA disease and limited to the purpose of giving birth to a healthy child.

"The US has been fairly conservative about a lot of embryo research and embryo manipulation," explained Dr Cedars. She added that sometimes people make slippery slope arguments suggesting that if you alter mtDNA now, maybe the technique will be used in the future to optimize for a trait such as athletic performance or cognition. She feels that these arguments are not justifiable and that, in reality, genetic engineering is not used for such purposes.


"There haven't been any babies born by this technique, which is why there was a need for this report," explained report author Jeffrey Kahn, PhD, MPH, from Johns Hopkins in Baltimore, Maryland, by email to Medscape Medical News.

Although the IOM acknowledged concerns about MRT, specifically recognizing the fact that MRT is new and the effects are currently unknown, they conclude that most of these concerns could be avoided by limiting its use. In particular, the committee made recommendations designed to minimize the risk for harm to the child born as a result of MRT.

Because the technique is not yet available clinically, the committee recommended that studies be performed to determine the safety and efficacy of MRT. The committee also suggested that all investigations of MRT pay special attention to consent in research, as well as communication of the novel aspects of MRT research to potential participants.

Furthermore, the IOM committee suggested that clinical investigations be limited to women who are at risk of transmitting serious mtDNA disease. In addition, only male embryos should be transferred for gestation.

Mitochondria are passed from the mother, so limiting the technique to male embryos would avoid introducing heritable genetic modifications into the human population. Such an approach would thus limit the effect on future generations.

"It's very exciting and a potential way to treat a very serious disease," enthused Dr Cedars. Limiting initial efforts to boys also represents a middle-of-the road approach, she explained.

Should initial investigations of MRT prove successful, the committee recommended that the FDA consider extending MRT research to the transfer of female embryos.

United Kingdom

MRT was approved in the United Kingdom last year.

At that time, medical ethicist Art Caplan, PhD, from the New York University Langone Medical Center in New York City, provided some perspective for Medscape Medical News. "There certainly is room to debate where we want genetic engineering to go. I would argue that mitochondrial transplant is the wrong place to draw the line. Preventing parents who want to try to have a healthy child who can live does not seem to be the right place to say no to this form of genetic engineering."

Likewise, Dr Cedars was not surprised by the conclusions of the IOM report. She felt that the arguments in favor of MRT were strong. The recommendations made by the IOM were sensible, and somewhat conservative.

The authors and Dr Cedars have disclosed no relevant financial relationships.

Mitochondrial Replacement Techniques: Ethical, Social, and Policy Considerations. IOM. Published online February 3, 2016. Full text


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