I have my parents, and biotechnology, to thank for bringing me into this world; I was an IVF baby. Given this intimate connection with technology and test tubes, you might think I'd be a cheerleader for all developments in the field. But a new technique under consideration has broad and troubling implications, not only for hopeful parents-to-be and their potential future children, but for all of humanity.
This new technique, called mitochondrial replacement or "three-parent IVF," would make genetic changes to IVF embryos and thus to every cell of the children born as a result of it. And these changes would be passed down to future generations. Human inheritable genetic modification of this kind is currently prohibited in over 40 countries and by several international agreements due to numerous problems and concerns. But proposals that would break this long-respected international consensus are now under consideration in the United Kingdom and the United States.
The UK has been toying with the idea for some time and may soon change its law to allow clinical trials. Several US researchers also want a piece of the action; at their request, the FDA had planned to hold a public meeting to discuss the technology On October 22 and 23. Due to the government shutdown, the meeting has been postponed and the agency has yet to release any background materials, but a recent NPR segment and Nature article provide some details.
The goal of the new technique is, in one sense, the same as with all IVF procedures: to allow parents to have an (at least partially) genetically related child. But mitochondrial replacement requires genes from three people, and a biologically radical process to combine them. It is being proposed for a small number of women who suffer from a particular kind of severe mitochondrial disease (many kinds are actually caused by nuclear DNA, which this procedure would do nothing to help.) The idea is that replacing the unhealthy mitochondria in an affected woman's egg with the healthy mitochondria of a donor's egg could produce a disease-free child (that could have Dad's eyes and Mom's bone structure).
It's an enticing story, and some insist that the technique should be made available as quickly as possible. Unfortunately for the families whose hopes have been raised, the feel-good story of a "life-saving treatment" covers up critical safety and efficacy problems, and hugely important social and ethical considerations.
On the safety front, there are a number of concerns for the women involved. The raw material needed for this experiment - women's eggs - would have to be extracted from at least two different women. The low success rate shown in research studies suggests that many eggs would be needed - more than in traditional IVF or egg donation procedures (106 were used for one study from Oregon Health and Science University.) The process of extracting large numbers of eggs is both painful and time consuming, and carries short and long-term health risks.
There are also profoundly worrying safety and efficacy concerns for any resulting children, which a growing number of scientists are speaking up about.
Would parents be comfortable subjecting their future child to this degree of biological experimentation? Peggy O'Mara, mother of four and founder of mothering.com and peggyomara.com, wouldn't be; the non-profit organization, Mothers for a Human Future, lists ten reasons why we shouldn't be. This ethical dilemma would only be compounded by the fact that an effective, less invasive option already exists. IVF combined with preimplantation genetic diagnosis (PGD) can screen embryos and implant one that has a very high probability of being healthy. Prenatal screening, egg donation and adoption are additional options.
- A paper published in Science by three evolutionary biologists states that "it is premature to move this technology into the clinic at this stage." The authors argue that the risks have been downplayed, particularly regarding the "fine-tuned coordination" between mitochondrial and nuclear DNA, and that relevant experiments in animals (with worrying outcomes) have been overlooked.
- Scientists from the University of California, Davis just published a paper explaining that though there aren't many genes outside of the nucleus, they have a disproportionate effect on cell metabolism and phenotypic variation, and that this fact could complicate the efficacy of "three-parent embryos."
- Stuart A. Newman, a Professor of Cell Biology and Anatomy at New York Medical College, called the techniques "inherently unsafe" in a Huffington Post article earlier this year, pointing out that, "Unlike in vitro fertilization (IVF) which generates embryos from the biological components that evolved to serve this function, the two methods under consideration by the HFEA de- and reconstruct the fertilized egg in radical ways, unprecedented in the history of life."
- Paul Knoepfler, an Associate Professor in the Department of Cell Biology and Human Anatomy at UC Davis School of Medicine, recently wrote a post at the Knoepfler Lab Stem Cell Blog in which he questioned whether mitochondrial replacement has any clinical relevance given the serious safety risks. He wrote, "Moving one oocyte nucleus into the enucleated oocyte of another person could trigger all kinds of devastating problems (most likely through epigenetic changes) that might not manifest until you try to make a human being out of it. Then it's too late."
There are larger social and ethical considerations that mitochondrial replacement also forces us to confront. Most importantly, this technology raises one of the thorniest questions humanity will ever face: are we willing to genetically modify future generations of humans?
The technique under consideration isn't like gene therapy, which modifies a specific location in the genetic makeup of one person who consents to the treatment. What is at stake here is much broader: the modification of the germline, the inheritable genetic code that connects humanity from one generation to the next. Members of the Council of Europe recently declared that such technologies are "incompatible with human dignity." And, as Bill McKibben puts it in his book Enough: Staying Human in an Engineered Age, "The stakes in this argument are absurdly high, nothing less than the meaning of being human."
Every country that has previously considered human inheritable genetic modification has banned it. The United States has relied on FDA guidelines to largely prevent rogue fertility specialists from attempting it. As 30 bioethicists from around the world pointed out in a letter to The Times, breaking this international consensus by providing regulatory approval for one technique would set an extremely troubling precedent, and potentially open the door to further kinds of genetic engineering.
This prospect makes it clear that we desperately need policy lines separating beneficial and harmful uses of reproductive and genetic technologies. IVF is expensive and not always effective or harmless, but it plays an important role in a world in which families come in all shapes and sizes, a world in which women are increasingly pressured to postpone having children until after their careers have stabilized. Inheritable human genetic modification, however, offers an entirely different prospect: not merely that it can help couples have a healthy child, but that it can create a better child. And if we open Pandora's Box to allow just one technique for just one reason, will we really be able to close it again?
So, I just can't agree with the recent article in The Scientist, which compared the unease around mitochondrial replacement techniques to the initial unease surrounding traditional IVF. I'm glad that people were concerned about the welfare of us IVF kids, but mitochondrial replacement (which is much closer technically to reproductive cloning than it is to traditional IVF) is exponentially more problematic.
In 2002, George Annas, Lori Andrews, and Rosario Isasi published a report in the American Journal of Law and Medicine titled "Protecting the Endangered Human: Toward an International Treaty Prohibiting Cloning and Inheritable Alternations" in which they argue,
Altering the human species is an issue that directly concerns all of us, and should only be decided democratically, by a body that is representative of everyone on the planet. It is the most important decision we will ever make.In the UK, a public consultation was held by the quasi-governmental agency that oversees fertility treatments and embryo research, but that process was not good enough. Hopefully the FDA's first public meeting on a form of human inheritable genetic modification will mark the beginning of the desperately needed, much larger conversation about these issues. I hope that this discussion will also raise awareness and improve access to healthcare for the people who are already alive and struggling with mitochondrial diseases today.
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