What Is a Three-Person Embryo?

Even though in-vitro fertilization (IVF) is no longer considered the least bit experimental, there are still plenty of aspects to it that scientists continue to work on, namely in pursuit of increasing success rates given that it’s still a costly treatment. While improving the process of IVF is one avenue of research, a newer, more cutting-edge aspect is genetic modification using the DNA from a third party donor, which can increase success rates by correcting genetic abnormalities in the embryos a couple creates together.

This technology currently exists, and the first baby was born from it in 2016 -  an apparently healthy baby boy born to parents from Jordan, assisted by an American doctor who created the embryo in an American lab, with the embryo transfer performed in Mexico because implanting a genetically-modified embryo is currently illegal in the US. But what exactly is and why is it illegal?

Currently, the experimental work of creating three-person embryos is aimed at women who carry a genetic abnormality affecting the mitochondria of the cells – known as the “powerhouse” of the cells because they convert food into energy that’s usable by the human body. While not every type of mitochondrial disease is fatal, many forms are and women who carry the fatal gene in their DNA have no chance of conceiving a baby who can live past the age of two or three.

The most recent development in genetic modification looks to be able to eliminate the marker for mitochondrial disease through use of a third source of DNA used to replace the faulty genes the mother carries. When creating the embryos in the lab, the embryologist isolates the nucleus in the mother’s egg and removes it. The embryologist then implant’s the mother’s nucleus into a donor egg in which the nucleus has been removed, so the mother’s nucleus (which contains the majority of the cell’s genetic material) is now surrounded by healthy mitochondria. This modified egg is then fertilized with the father’s sperm and then implanted into the mother as with any other IVF treatment.

When initially performed, five embryos were created and only one of them was found to be healthy, but that one embryo resulted in a baby born nine months later. How likely is this technique to take off and become more widespread, essentially offering parents insurance against fatal forms of mitochondrial disease, and eventually, other fatal diseases?

The future success of these techniques is uncertain at this time, at least in the United States. The process has been reviewed and is protected by law in the United Kingdom (which, incidentally, led the world with the first IVF baby born – Louise Brown), but its future is less certain in the United States. Medical ethics advocacy groups have raised concerns that being able to affect control over genetic expression is a Pandora’s Box just waiting to explode open and can all-too-easily result in the pursuit of eugenics – or the quest to create “genetically superior” children. Since this technology has become publicly known, I’ve seen plenty of opinion pieces asking if scientists will seek to eliminate congenital conditions such as deafness, blindness, dwarfism, even autism, which some people see not asdisabilities, but as differences. It’s a valid point.

But I don’t think it’s a valid enough point to hold back further research on the life-saving aspects genetic modification may hold. Right now the technique is employed for mitochondrial defects, but in due time scientists may be able to locate and even eliminate genetic predispositions to other fatal conditions such as Tay-Sachs disease, Trisomy 13 or 18, Cystic Fibrosis, Canavan Disease, even some forms of cancer. Over the course of many generations, many of these fatal diseases may be able to be eradicated.

It’s hard to argue that it’s unethical to try to eliminate fatal diseases, but some people and/or groups attempt to make the case that humans should not intervene with the disease portion of natural selection. I would hazard a guess that it’s unlikely that these people have lost a child or loved one to a degenerative genetic disorder. But like any new development on the scientific and medical frontier, it takes time for significant changes to be widely accepted.

For certain, we are just on the very forefront of human genetic modification and more research needs to be done on both the techniques and the long-term implications on human health. But the possibilities of helping couples have children when they otherwise stood no chance are a bright spot, and one we should keep our eyes on for future developments.