Gene-Edited Babies: Why Scientists Are Debating the Risks, Benefits and Ethics

When Chinese scientist He Jiankui announced in 2018 that he had created the first gene-edited babies, the experiment was widely criticized as reckless and premature. He was later sentenced to prison.

That controversy has not stopped efforts to develop gene-edited human embryos. Biotech entrepreneur Kathy Tai argues that advancing the technology is not only an emergency but also a “moral obligation.”

Tai is the 30-year-old founder of Origin Genomics, a company founded in March with plans to bring gene-edited embryos to IVF clinics. In a new commentary published in Trends in Genetics, she calls for public funding and new regulatory pathways to advance research on gene-edited embryos and eventually move the technology into clinical use.

However, major questions remain about what evidence would be needed to determine whether gene-edited embryos are safe enough to use in human pregnancy—and what risks could remain for the resulting child.

“There’s a cautionary tale of the first human trial in which a person died without any red lights flashing,” said Hank Greeley, a law professor and director of Stanford University’s Center for Law and Biological Sciences.

What is germline gene editing?

Germline gene editing involves modifying cells involved in human reproduction, including embryos. The changes may be passed on to future generations. In theory, the technology could permanently correct a devastating genetic mutation.

But accidental changes to other parts of the DNA, known as “off-target effects,” could create new health risks that are also passed on to future generations. This risk is one reason dozens of countries prohibit editing human embryos for the purpose of pregnancy.

How IVF and genetic screening compare

For people at risk of passing a genetic disease to their children, in vitro fertilization can be combined with genetic screening. This process identifies embryos that do not carry the disease before they are implanted in the uterus.

Critics of embryo editing argue that improvements in screening have reduced the need for gene editing. Greeley said gene-edited embryos would help “a small percentage of people.”

The drawback of current approaches is that IVF is inefficient. Even people without a known genetic disorder may have difficulty obtaining viable embryos. During an IVF cycle, eggs may not be fertilized, and fertilized eggs may fail to develop or may contain chromosomal abnormalities. Genetic screening can further reduce the number of embryos available for implantation.

Ian Watts and Cheyenne Ziegler experienced these challenges while trying to have a child without the genetic mutation that causes Watts’ Charcot-Marie-Tooth disease, a neurodegenerative disorder that affects motor skills.

Three rounds of IVF produced eight chromosomally normal embryos, but only three did not carry Watts’ mutation. The couple believes those three embryos may not be enough to have the three or four children they hope to raise.

“Right now, the choice is either not to have children or to do a lot of IVF,” said Watts, a 36-year-old engineer who lives in Long Beach, California. Gene editing could give people like him another chance to build a family.

Gene editing may also be helpful for couples in rare situations where all of their embryos inherit a disease-causing mutation, such as when both partners have two copies of a harmful mutation.

“We’re here to treat these diseases; we don’t just exclude embryos and call it a day,” Tai said. The former Thiel researcher has referred to herself as “Biotech Barbie.”

Can newer gene-editing tools make embryos safer?

The invention of CRISPR raised the possibility of gene-edited babies more than a decade ago. Newer forms of gene editing have since improved precision.

In June, researchers at Columbia University reported that they had used a technique called base editing to modify early-stage human embryos with high precision.

Tai cites this work in her commentary and argues that precise gene editing is now within reach. But researchers and ethicists continue to debate whether the technology is safe enough for human pregnancy—and how regulators should evaluate the risks before gene-edited embryos enter clinical use.