On Monday, February 2, the UK Parliament voted to permit the creation of “three-parent embryos.” If the House of Lords follows suit next month, which is expected, the UK will become the first country in the world to permit the creation of human embryos with genetic material (DNA) from three different people.
The controversial procedure known as mitochondrial DNA transfer  is a treatment for mitochondrial diseases . Mitochondria are tiny battery-like structures inside of cells that produce energy and are necessary for a host of important cellular functions. Each mitochondrion contains a small amount of DNA. When that DNA is faulty (“infected”), the organs and systems of the body can fail causing heart disease, strokes, muscle wasting, epilepsy and even death.
Mitochondrial DNA only passes through the maternal line. This means infected mothers can pass the diseases to their children, but infected males cannot. Consequently, the idea of purging human reproduction of faulty mitochondria was conceived.
The procedure is ordinarily carried out in one of two ways.
Since an egg’s mitochondria reside in the cytoplasm, the DNA in the egg’s nucleus of a woman with mitochondrial disease is free of infected DNA. Consequently, the first way is to “enucleate” (i.e., remove the nucleus from) an egg with infected mitochondrial DNA and transfer the (uninfected) nucleus into the enucleated egg of a third party donor who is free of the disease. The “new” egg, created from two mothers, is then fertilized with male sperm in vitro.
In the second and preferred method, two embryos are created, one using an egg from an infected mother and a father’s sperm; and the second from an egg donor free of the disease and donor sperm. The nucleus of the infected embryo is then removed, which is lethal to the first embryo; and the nucleus of the uninfected embryo is removed and discarded, which is lethal to the second embryo. A third embryo is created using the uninfected nucleus from the first embryo, and the enucleated egg from the second embryo. Notice that this “nuclear transfer” is a kind of human cloning.
Mitochondrial DNA Transfer Using Embryos
Both techniques create a human embryo with genetic material (DNA) from three parents: the infected mother, the woman who supplied the uninfected egg, and a male.
In a recent article  entitled “Is It Ethical to Create Babies From Three DNA Sources?” bioethicist Art Caplan of the NYU Langone Medical Center replies, “Absolutely.” I would like to reply to his argument.
Caplan says the procedure is no more radical than giving “the battery from my car to a friend whose battery has died.” But for several reasons this analogy fails. First, since an egg has approximately 100,000 mitochondria, it’s not one battery, but 100,000 batteries. Second, both the batteries and the car are alive. Third, the identical profile of the 100,000 batteries will be transmitted ad infinitum to progeny within the car’s lineage. And fourth, unlike any automobile, the embryo will be an autonomous human being, who will love, sorrow, suffer and die. But no embryo will ever be consulted on what he thinks about being created by this procedure (so much for patient autonomy and informed consent); he will merely be told one day: “We made you with DNA from three parents for your own good.”
How about the question of safety? “The case for moving forward,” Kaplan says, “is strong.” Based upon what? Based upon the fact that in 2012 “viable” primate embryos were created using the procedure. This is not a strong case. Even if we have good reason to believe that viable human embryos are possible, we haven’t the foggiest notion of what effects the procedure will have on people’s lifelong development. Nor can we have anything approaching certitude that the confusion of parentage (“how many parents do I have?”) will not cause mental distress in the adult children created by this procedure. This ignorance alone is enough to put an absolute prohibition on human trials.
But there are at least three more ethical problems. First, there is the immorality of creating human embryos in order to lethally exploit them for their body parts. Second, there are the perennial ethical problems raised by creating children in vitro. And third, there is the very real danger of eroding our moral inhibitions against “germline engineering,” where each genetic alteration introduced is inherited by every single offspring of any child created from the procedure.
Fertility specialists plan to begin using the method in earnest next fall when the new law comes into effect. Barring any unanticipated obstacles, the first three-parent babies will be born in 2016. It won’t be until the 2030s before we can ask them whether they believe Parliament’s decision to permit their creation from three DNA sources was ethical.