The Fear-Mongering Of ‘Three-Parent IVF’
Last year, when the United Kingdom became the first country to pass laws permitting mitochondrial donation, a seemingly innocuous fertility procedure made international headlines when it was billed as “three-parent IVF.”
The confusion and outrage was immediate. One embryo created using genetic material from three parents? What’s next, creating caveman babies using the DNA of frozen neanderthals? What is society coming to? Oh, the (lack of) humanity!
While referring to the procedure as “three-parent IVF” makes for compelling copy, in reality, it is not accurate. It’s also not nearly as controversial or ethically problematic as the “three-parent” moniker makes it sound. Sorry to disappoint.
First of all, the reason behind mitochondrial donation is to prevent women with life-threatening genetic conditions from passing them down to their children — not to serve as a means of creating the perfect human by combining the DNA of those with desirable traits (for instance, a body like Arnold with a Denzel face while boasting the smarts of Stephen Hawking and the charm of Michelle).
The possibilities for fiction are, of course, limitless — and serve as a compelling thought experiment. But that’s not why we’re here.
Here’s how it works:
Sperm and an egg from two humans who wish to have a baby together are used to create an embryo. But the egg provider in this scenario has a genetic condition inherited through mitochondria, so the genetic material within the nucleus of the fertilized egg is removed and placed in a fertilized donor egg with healthy mitochondria. Mitochondria act like batteries within an embryo, providing energy to allow them to develop, but the introduction of this material does not seriously alter most of its DNA.
Technically, the resulting child would inherit DNA from the sperm provider and both egg providers, but all of the 20,000 genes on the child’s 23 pairs of chromosomes come from the primary egg and sperm providers; less than 0.2% of the total DNA would come from the donor egg.
In a study published in Nature in June 2016 — involving more than 500 eggs from 64 donor women — researchers from Britain’s Newcastle University reported that pronuclear transplantation (one of three mitochondrial donation procedures, and currently the one used in the UK) does not harm embryological development, and has the potential to reduce the risk of inherited mitochondrial conditions, though it may not guarantee prevention. Additionally, the study found that embryos created using mitochondrial donation were indistinguishable from conventional IVF embryos.
“The key message is that we have found no evidence the technique is unsafe. Embryos created by this technique have all the characteristics to lead to a pregnancy,” according to Professor Doug Turnbull, Director of the Centre for Mitochondrial Research, and co-author of the paper. “Our studies on stem cells do express a cautionary note that it might not be 100% efficient in preventing transmission, but for many women who carry these mutations, the risk is far less than conceiving naturally.”
Most of the diseases that mitochondrial donation would help to eradicate affect children before adulthood and are often fatal, including Leigh’s disease, progressive infantile polio dystrophy, and Barth syndrome. More common medical conditions, such as Parkinson’s, deafness, failing eyesight, epilepsy, and diabetes, have also been linked to faulty mitochondria.
Another important finding of the Newcastle University study is that pronuclear transplantation will work best if the fertility patient (rather than donor) eggs are frozen, therefore making it possible for women with mitochondrial abnormalities to freeze their eggs for future use, and avoid age-related decline of egg quality.
So what’s the problem? Aside from the usual “it’s not natural” complaints, there are two primary ethical concerns with mitochondrial donation. The first is the dreaded “slippery slope” argument: that once this technology is permitted in assisted reproduction, it will result in “designer babies,” a strong favoring of one sex over the other, or a mutant army of Justin Biebers.
While all legitimate concerns, they won’t be possible via mitochondrial donation: Characteristics like hair and eye color are controlled by nuclear DNA, which in this procedure, only comes from the two primary parents.
The second concern stems from the fact that it is germline modification; in other words, donated mitochondria are passed on to future generations, which some see as ethically problematic, as the future descendants would not have the opportunity to consent to the treatment. Others argue that if we have the technology to help improve the lives and health of future generations, we are morally obligated to use it. While there are other procedures that — for better or worse — strip future children of their ability to consent (think: everything from in utero surgical procedures, to doctors and parents making decisions regarding the genitalia of a baby born intersex), mitochondrial donation goes one step further, impacting not only a fetus or infant, but future generations as well.
Professor Mary Herbert, senior author of the study, said: “Having overcome significant technical and biological challenges, we are optimistic that the technique we have developed will offer affected women the possibility of reducing the risk of transmitting mitochondrial DNA disease to their children.” (Herbert also thanked the women who donated their eggs that made this research possible.)
When it comes to assisted reproduction, there is no shortage of policies and procedures that could, under certain circumstances, do more harm than good if left unrestricted, like sex selection or certain forms of preimplantation genetic diagnosis. What we should be concerned about is reproductive policies that restrict necessary care or limit options for potential parents — not a poorly-named tactic used to limit life-threatening medical conditions.