When the Chinese Scientist He Jiankui announced in 2018 that he had created the first genetically modified babies, the experiment was widely condemned as reckless and premature. It ended with Him in prison.
But that hasn’t stopped the campaign for gene-edited human embryos, with biotech entrepreneur Cathy Tie saying it’s not just urgent: it’s a “moral imperative.”
Tie is the 30-year-old founder of Origin Genomics, a company launched in March with the intention of introducing genetically modified embryos into IVF clinics. In a new commentary published in the journal Trends in Genetics, she argues for public funding and new regulatory pathways to advance genetically modified babies and eventually move into clinical use.
But questions remain about what evidence researchers will need to determine whether genetically modified embryos are safe enough to attempt human pregnancy — and what risks might remain for the resulting children.
“There are cautionary tales about early human trials where there really wasn’t a flashing red light and people died,” says Hank Greely, a law professor and director of the Center for Law and Biosciences at Stanford University.
So-called germline gene editing involves modifying cells involved in human reproduction, such as embryos. Any changes made could be passed on to future generations. This could mean, for example, permanently correcting a devastating genetic mutation. But accidental changes to DNA elsewhere, known as “off-target effects,” could introduce new health risks that could also be transmitted. These high stakes partly explain why dozens of countries have banned the genetic modification of human embryos intended for pregnancy.
People at risk of passing a genetic disease to their children can use IVF combined with genetic screening to identify disease-free embryos before they are transferred to the uterus. Critics of embryo editing say screening tools make the need for it very small. According to Greely, genetically modified embryos would help “a fraction of a fraction of a fraction.”
The downside of the current approach is that IVF is ineffective; It can be difficult to obtain viable embryos, even for people not at risk of hereditary disease. Ian Watts and Cheyenne Ziegler, for example, underwent three rounds of IVF in an effort to have children who would not carry the genetic variant that causes Watts’ Charcot-Marie-Tooth disease, a degenerative neurological disorder that affects fine motor skills and mobility. With any IVF cycle, eggs are usually not fertilized, and those that do often slow their development or have chromosomal abnormalities. Adding additional disease screening means that some viable embryos are also not retained.
In Watts and Ziegler’s case, three IVF cycles produced eight chromosomally normal embryos, but only three without Watts’ variant. These three embryos probably won’t be enough to give the couple the three or four children they hope to one day have.
“The choices currently available are either not to have children or to do a lot of IVF,” says Watts, a 36-year-old engineer in Long Beach, California. Gene editing could give people like him a better chance of starting a future family. It could also help couples in the extremely rare situation where each embryo inherits a disease-causing mutation, such as in the case of partners each having two copies of a harmful variant.
“We’re here to treat these diseases, not just to exclude embryos and end this story,” says Tie, a former Thiel fellow who describes herself as a “biotech Barbie.”
The invention of CRISPR raised the possibility of genetically modified babies more than a decade ago, and new forms of genetic editing offer increasing precision. In June, researchers at Columbia University revealed that they had edited early-stage human embryos using a technique called base editing with incredible precision. Tie cites this work in his commentary, saying that precision editing is now within reach.
Gn Health
