This article is part of DNA/IDK , a semi-regular column exploring how genetic modification is shaping the future. Follow along here .
A Chinese researcher announced that he edited the DNA of two twin girls born earlier this month to make them naturally resistant to HIV and other diseases. If this research turns out to be legitimate, these babies will be the first in the world to be born with an edited genome.
He Jiankui, a geneticist who formerly studied at Rice and Stanford in the US, made the announcement on Monday ahead of a major international summit on human genome editing. According to MIT Technology Review, He edited the DNA for embryos carried by seven different couples, although he declined to name the couples or the status of the other babies at the request of the parents.
“I feel a strong responsibility that it’s not just to make a first, but also make it an example,” He told the Associated Press. “Society will decide what to do next.”
He said he used CRISPR-Cas9 to edit the genomes of the human embryos. CRISPR uses an enzyme called Cas9 to excise small portions of DNA and introduce genetic changes at that location. The core element of the CRISPR system is a small piece of RNA that binds to a specific DNA sequence in a genome and the Cas9 enzyme. Once the RNA is bound to the DNA sequence, Cas9 cuts the DNA at the targeted location and the cell’s natural DNA repair mechanisms work to repair the DNA sequence.
In the case of the newborn twins, He told the Associated Press that he edited their DNA to make them naturally resistant to HIV, smallpox, and cholera.
The scientific community has expressed mixed reactions to He’s announcement so far. In the first place, it’s not certain that the breakthrough has actually occurred. He hasn’t followed the standard procedure of publishing his results in an academic journal where it can be peer reviewed by other genetics experts. He also isn’t releasing any details about the couple that conceived the children. The only clue that He’s claims are legitimate are documents posted on the website for Southern University of Science and Technology, where He has been on leave since earlier this year.
According to the Associated Press, the Southern University of Science and Technology said that He’s work “seriously violated academic ethics and standards” and planned to investigate.
There’s also the question of whether He has made a gross ethical misstep by editing viable human embryos. Although CRISPR has been used to edit the genes in adult humans to successfully treat numerous diseases, until now it hadn’t been used to edit the genome of an embryo that was brought to term. In the United States, editing the genome of embryos is limited to labs and genetically modified embryos are always terminated long before they begin to mature into a fetus.
The concern about embryonic genome editing largely stems from uncertainties about how this process will affect later generations. Unlike editing the genome of an adult human to treat a disease, messing with embryonic DNA induces genetic changes that can be passed on to later generations. A related problem is that CRISPR has been known to produce unwanted genetic mutations, which could potentially lead to unforeseen health issues in the newborn twins.
In China, the rules about genome editing are slightly more relaxed than in the United States, however. Although outright cloning of humans is still considered illegal, editing the genomes of human embryos is not. This relative leniency when it comes to genetic engineering has allowed China to make a number of notable advances in recent years—including producing the first cloned monkeys, which was considered a major hurdle on the road to creating the first human clone.
It’s also worth noting that this isn’t the first time scientists have claimed to have produced a genetically modified baby without providing the evidence to back it up. In the early 2000s, researchers linked to a cult claimed to produce the first human clone, which ultimately turned out to be a complete fabrication. Nevertheless, the announcement caused widespread panic about the potential of cloning and led to a number of laws banning the practice to be adopted around the world. China isn’t exactly known for its honesty when it comes to scientific research: Last year, the New York Times reported that China has retracted more fraudulent peer reviewed papers since 2012 than every other country combined and a number of high profile research results haven’t been replicated by other scientists. On the other hand, genome editing technology is at a point where He’s claims are utterly plausible. For now, however, the jury’s still out on whether He has ushered us into the brave new world of designer babies.