Genetic knowledge has played a direct role in pregnancy for more than 50 years, since the first use of amniocentesis to extract amniotic fluid containing fetal cells and DNA for analysis. Noninvasive prenatal testing (NIPT)—which is significantly cheaper than amniocentesis and, requiring only a blood draw, can be done earlier in pregnancy—started a decade ago and is now common. NIPT will only become better, providing more-accurate information on risk for thousands of rare genetic conditions and dozens of more-common diseases. It’s just one of the technologies poised to transform pregnancy over the coming decades.
Today, bad news from prenatal testing leaves would-be parents with two options: terminate the pregnancy or prepare for the birth of an ill or at-risk child. For over 30 years, parents have been able to avoid this dilemma by turning to pre-implantation genetic diagnosis (PGD). This procedure starts with in vitro fertilization (IVF), but then tests embryos before they are transferred into the uterus. For many people, choosing not to transfer an embryo destined to have a genetic disease raises less concern than aborting an already implanted embryo or growing fetus.
PGD opens yet another door. One might edit the genes of those at-risk embryos, using CRISPR or other methods, before using them to try to start a pregnancy. Infamously, Chinese scientist He Jiankui used embryo editing to make babies three years ago. In this case, rather than trying to head off genetic disease, He was attempting to confer HIV resistance by introducing mutations in CCR5, a gene that encodes a cell-surface receptor that the virus latches onto to infect T cells. He expected acclaim, but instead was condemned around the world and ultimately sentenced to prison. For many people, He’s sin was changing the babies’ DNA in ways they could pass on to their children, because changed cells in the embryo would eventually become eggs or sperm. This argument against heritable changes would also apply when the change is made to correct disease-causing mutations—or when it is used to try to “enhance” the resulting babies. Whether such germline editing should be a “line in the sand,” not to be crossed, is hotly disputed.
My new book, CRISPR People: The Science and Ethics of Editing Humans, tells this story of human germline genome editing in depth, including He’s experiment and the many problems with it. But if the process of editing the DNA of embryos is eventually shown to be safe and effective, it might end up being adopted, especially as we continue to improve our understanding of genetics. As we learn more about the effects of genetic variations, gene editing technologies will have more to offer. Most of us look forward to this when it involves disease, while the (distant) prospect of “enhancement” of traits such as height or intelligence causes very mixed feelings.
Now, consider that we may soon be able to make eggs and sperm from stem cells derived from a person’s skin. This technique, which has already worked in mice and is being researched with human cells, offers hope to people who cannot have their own genetic children because they lack functional sperm or eggs, as well as a potential pathway for LGBTQ couples who want to have children who are biologically their own. If the technique becomes an easy source of human eggs, it may also allow people to bypass the uncomfortable, risky, and expensive process of harvesting eggs for IVF, which could lead to a vast expansion of the use of PGD.
Finally, in several decades, one might be able to make a living uterus outside the body using stem cells and, by mechanically giving it blood with oxygen, nutrients, and the right hormones, use it to gestate a baby. This not-exactly-artificial womb could transform pregnancy entirely, and with it, the lives of billions of people.
Some of these developments will come to pass, some will not, and some things that I have neither discussed nor dreamt of will happen. While these advances could bring great benefit, they could also be abused, creating in real life the familiar dystopias of the breakdown of family structures, state control over parental decisions, or genetically stratified societies. We need to watch these biomedical possibilities to make sure they deliver a better tomorrow.
Henry T. Greely is Professor of Law, Professor by Courtesy of Genetics, and Director of the Center for Law and the Biosciences at Stanford University. Read an excerpt from CRISPR People here.