OPINION:
On July 16, The New England Journal of Medicine published the results of a study in the U.K. that resulted in the births of eight children via a new form of in vitro fertilization treatment.
These efforts were undertaken to prevent diseases caused by defects in the energy-producing parts of cells, called mitochondria, which come from the mother’s eggs. The procedure used in this study is called mitochondria donation, and it involves taking the nucleus of a fertilized egg from a mother with mitochondrial disease and transferring it to a egg from a healthy woman that has had its nucleus removed.
While the initial reports indicate that the children have been successfully spared from the mitochondrial diseases that the researchers were trying to avoid, the mechanism used to give rise to these children has created serious ethical concerns about human existence and personhood.
Normal human fertilization involves the fusion of one cell from the mother (the egg) and one cell from the father (the sperm) to create a single cell (the zygote) whose nucleus contains DNA from both, half from the mother and half from the father. One added layer of complexity is that, aside from the DNA in the nucleus, the zygote also contains extra DNA from the mother inside the mitochondria.
Even though the amount of DNA found in the “powerhouse of the cell” is small, less than 1% of the total DNA in the cell, it still encodes for dozens of genes that are essential for cells to function normally. This means that the eight children who were born in the U.K. study contained DNA from three people; that is, they all have three parents.
While there have been recent breakthroughs in the modification of human DNA sequences for the treatment of disease that have been (and should be) widely celebrated, such as the treatment of metabolic disease and sickle cell disease, these treatments have occurred in such a way that the changes to the patient’s DNA are not passed down to the patient’s offspring (i.e., the changes only occur in somatic cells). However, in 2018 a Chinese scientist edited the DNA sequence of twin babies (the so-called “CRISPR babies”) in such a way that the changes would be passed on to their offspring (by editing the germline).
This experiment was widely condemned by the scientific community for both its lack of regulation and its breaking of a nearly unanimous ethical barrier in biomedical research.
In addition to the ethical concerns of inheriting DNA from three people, the babies created using mitochondria donation have also effectively had their germline edited. Since mitochondria are inherited from the mother, any females born as a result of mitochondria donation will pass on the mitochondria they inherited to their own offspring.
For this reason, scientists previously advised only using this procedure to produce male children. However, four of the children born in the U.K. study were female and will thus pass on their inherited mitochondria to their future offspring (and to each subsequent generation of female offspring).
Since its inception, IVF has precipitously fallen down a slippery slope. What started out as a procedure to help men and women who were unable to become pregnant naturally have children has grown to include producing embryos for same-sex couples, the selection of desirable traits in embryos, the use of human embryos in scientific research and now the generation of embryos from three people in such a way that the DNA from all of them could be passed to future generations.
These new procedures demand that the ethical questions surrounding IVF be revisited.
Before IVF and its subsequent developments, it was taken for granted that all human persons were the result of a union between the reproductive cells of one man and one woman, both of whom had moral and legal obligations to their offspring. Now, there are embryos created and children born who may never know the man and woman (possibly two women) from whose cells and DNA they get their very being.
It is incumbent on medical ethicists and regulators to think critically about how far they are willing to let us slide down this slope.
• William Mills is an assistant professor of Biology at Mount St. Mary’s University in Emmitsburg, Maryland.
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