by Dr. Heather Kuruvilla
Since Britain legalized the creation of 3-person embryos on February 24th, I’ve been asked a number of questions about this procedure. Below are a few commonly asked questions as well as some resources that I hope will be helpful.
Why is this procedure sometimes called making a “3-person embryo”? Gametes from three individuals are being used to create one embryo. The biological mother and father contribute eggs and sperm respectively. However, in this case, the nuclei of the biological mother’s egg and the father’s sperm will be injected into an enucleated donor egg that has healthy mitochondria.
Whom would this procedure help? The procedure would enable women with mitochondrial disease to bear healthy children who are biologically related to them. Mitochondria are cellular organelles that are passed down from mother to child. Therefore, a woman with mitochondrial disease would normally pass diseased mitochondria to her offspring.
Will embryos be destroyed in order to carry out this procedure? It depends upon how the procedure is carried out. There are several methods by which 3-person embryos can be made, and not all are embryo destructive. I’ve linked an article from the Center for Genetics and Society below. Using their definitions, pronuclear transfer would involve the destruction of embryos, but maternal spindle transfer and nuclear genome transfer would not. Polar body transfer would not directly result in the destruction of an embryo, but if the polar body were produced by fertilizing an egg so that the polar body could be produced, the resulting embryo would likely be destroyed since it would contain damaged mitochondria.
Is this procedure risky to humans? The short answer to this question is that we don’t know. It is a relatively untested procedure, which raises safety concerns. In addition, the Center for Genetics and Society (CGS) mention other concerns, such as violating an EU ban on modifying the human germline, risks to the women from whom eggs were extracted, and potential identity struggles that a person might face once he/she learns of the unusual circumstances surrounding his/her conception. CGS suggests preimplantation genetic diagnosis (PGD) as an alternative to the three-person embryo technology. However, since PGD generally results in the destruction of genetically imperfect embryos, this alternative cannot be supported by those who believe that embryos are human persons worthy of protection.
For more information: I’ve put links to several helpful articles below.