Last month, the United Kingdom voted to legalize “three-parent babies.” They are the first country to allow this procedure and within a year, the first of these babies will be born.
These babies will have three parents in an attempt to eradicate mitochondrial disease. In short, this disease is caused by mutations in the mitochondrial DNA which in turn leads to insufficient energy for the cell’s survival. The death of cells causes the organs to fail ultimately leading to death. This illness is passed through the mother to her children. There are three traditional choices for mothers with this disease that hope to have children. They can adopt a child, use a donor egg, or become pregnant and at 11 weeks have the fetus tested for mitochondrial disease. At that point, they can choose to terminate the pregnancy. However, there is new hope on the horizon for prospective mothers in the United Kingdom that have this disease. The government recently legalized a method of three-person in-vitro fertilization, mitochondrial donation.
There are two different methods of mitochondrial donation. The first is named maternal spindle transfer where the repair is completed before fertilization. An egg is taken from both the mother and the donor and both the nuclei are removed. Next, the mother’s nucleus is kept and inserted into the donor’s egg while the donor’s nucleus is destroyed. Then, the donor egg containing the mothers nucleus and healthy mitochondria is fertilized with the father’s sperm. Finally, the egg is implanted back into the mother.
The other method of fertilization is named pronuclear transfer. In this procedure, the repair is done after fertilization. First, an egg is taken from both the mother and the donor. Then, they are fertilized with the father’s sperm. Before the eggs have a chance to replicate, the chromosomes from each egg are taken out. Next, the donor ones are thrown out and the donor egg is filled with the mother’s chromosomes. Finally, the egg is implanted in the mother.
There are many ethical concerns attached to this issue causing countries including Canada to hold back on legalizing this procedure. In Canada, this specifically has to do with the fear of opening the doors to designer babies. Not only are designer babies horrifically dystopian and Brave New World-esque, it may also decrease the natural variability of the human race, something that is required for the race to survive and adapt. However, changing a baby’s mitochondrial DNA is a far cry from creating designer babies. The procedure has no effect on their hair or eye colour and it isn’t enhancing them in any way. In fact, the change affects less than 1% of the baby’s total genome.
Other ethical concerns include “germline” genetic engineering, the fact that one of the embryos are destroyed in the pronuclear transfer and that we are unsure of this procedure’s effects on humans. Even with these concerns, this procedure is worth it if we can eradicate a painful disease affecting millions.
Check out this video by Elliot M. that sums up mitochondrial replacement:
– Siana Lai