The United Kingdom House of Commons recently approved a dormant exception to the prohibition on human inheritable genetic modification contained in the 2008 Human Fertilization and Embryology Act. It provides that in certain circumstances, an embryo may be created using the genetic material from three people: the mother, father, and a donor woman. The procedure, a type of in-vitro fertilization, would help prevent inherited disease caused by mitochondrial DNA, which affects about one in 6,500 babies. Nonetheless, it remains a controversial practice due to the questions it poses.
How It Works
Mitochondrial disease is genetic, only being able to pass through the mother. The mitochondria are small structures within each cell, the principal function of which is to convert food into energy. They are commonly referred to as the “power-houses” of the cell, producing more than ninety percent of the energy the body uses to live and grow. The mitochondria also have other specialized functions that depend on which type of cell they reside in. When they are defective they do not produce enough energy or perform their functions properly, causing major bodily functions to fail. Mitochondrial disease specifically harms cells in the brain, heart, liver, skeletal muscles, kidneys, and the endocrine and respiratory systems. Symptoms include cardiac failure, mental development problems, and gradual muscle weakness to the point that the affected person suffers extreme fatigue and respiratory failure.
In the most extreme cases, babies born with mitochondrial disease do not make it to their toddler years. Sharon and Neil Bernardi, a couple who advocated for changing the law, lost all seven of their children to complications caused by mitochondrial defects. Sharon later found out that she had been her parents’ fourth attempt at having a child, the three prior attempts resulting in stillbirths. Further, doctors found out that members of her extended family had lost eight children in total. It is this type of tragic case that the proposed law intends to address. If it is passed, researchers at Newcastle estimate there would eventually be about 150 births per year in the UK using the new method, but the technique would be more limited during the first year, utilizing it for approximately ten cases.
The procedure was developed by researchers at Newcastle Univeristy. There are two proposed methods of carrying out Three-Person In-Vitro Fertilization (TPIVF). At a very basic level, the procedure combines the parents’ DNA with the donor’s mitochondria. The first procedure involves fertilizing both the mother’s and donor’s egg with the father’s sperm to create an embryo for each, then removing the nucleus from the donor egg and replacing it with the nucleus from the parents’ egg. The alternate procedure involves replacing the nucleus from the donor’s egg with the mother’s nucleus, then fertilizing it with the father’s sperm. Since mitochondria has its own DNA, that DNA from the donor passes to the child. The result is that 99.9% of the child’s DNA would come from its parents, and .1% would come from the donor. The child would pass on this new genetic composition created by the three people.
Objections to TPIVF mainly include ethical and safety concerns. With so little consensus in the international community on the subject, not everyone is convinced the procedure is safe and effective. First is the ethical question of whether to create a child with such little known about how it will affect the child in the long-run, and how it will have an affect after generations of this practice. Researchers are convinced the procedure is safe, largely because we know what the mitochondria does for our bodies, and because the percentage of DNA from the donor is very small. The main issue is that professionals do not know everything about the long-term implications of creating one child that will contain DNA from three people. This is a valid concern, but every new medical procedure begins with some degree of uncertainty.
One of the proposed regulations for TPIVF is that a regulator must assess each case to determine whether there is a significant risk of disability or serious illness to the child before allowing the procedure to take place. Advocates of the new method simply want the parents to be able to have a healthy child. One study by researchers at Newcastle indicates almost 2,500 women in the UK would benefit from this method
Again, what has been difficult for researchers to address are effects on the child later in life, when many mitochondrial issues tend to manifest. Based on studies with mice and invertebrates, there is also a concern of mismatches between mitochondrial and nuclear genomes. In these animals, interaction between the mismatched mitochondria and nucleus resulted in “[a]ltered respiratory metabolism and reduced performance, learning, and exploratory capacity” issues. Importantly, many of these health problems resulting the mismatch did not manifest until adulthood.
New studies are revealing that mitochondria do not only play a passive, functional role in bodies, but they actually affect certain traits of ours. An article by science journalist Garry Hamilton on NewScientist.com1 states that “[f]ar from being passive power plants, it seems mitochondria influence some of the most important aspects of human life – from memory and aging to combating stress and disease. They even have influence over the DNA in your cell nuclei . . .” Additionally, recent research suggests mitochondria have much more of an influence over us and play a key role in many of our functions. It is the possibility that this could result in the child inheriting some traits via the donor’s mitochondria.
Another concern comes from those who believe the flat ban on genetic modification in humans should remain in place. One public interest watchdog group in England fears that once we start this practice, “it would lead inevitably to a future of ‘designer babies’ and a new consumer-driven eugenics.” It argues that the only benefit to the mother is a social one, and that the family instead can use adoption or another woman’s eggs without the risks of the procedure, whatever they may be. While admitting genetic modification is a by-product, rather than the purpose of, TPIVF, once one exception is made, others are imminent.
Here in the United States, a committee of the Institute of Medicine, at the request of the Food and Drug Administration, began a series of meetings on the ethical and social policy issues raised by this type of method of preventing mitochondrial disease. These meetings will continue for the next fourteen months. The FDA has effectively banned this type of procedure since 2001, and will not fund research that results in modification of the human germline. Researchers at the Oregon Health and Science University have been working this same method for some time and used it on monkeys three years ago, which appear to still be healthy and developing normally.
This method of creating a child is unnatural and its results are unnatural, but one could say the same of many medical procedures. Both sides debate whether more research of the risks is needed. However, when you imagine being a mother who has lost seven children to a painful disease that can be prevented by a new procedure, perhaps it is worth the risk. This “slippery slope” argument is largely overshadowed by the fact that this procedure would not be attempted often. Further, the benefit it will provide if it works arguably outweighs the cost.