A Chinese scientist says he is the first to create gene-edited babies, provoking an international outcry among researchers 

Scientists have known for some time that a small subset of individuals carry mutations that thwart HIV. The mutations prevent the expression of CCR5 and CXCR4, cell-surface receptors that a handful of pathogens, among them HIV, exploit to enter target cells.

About a decade ago German researchers succeeded in curing a leukemia patient with HIV by transplanting bone marrow from a donor whose stem cells were missing the CCR5 receptors, and the dawn of genome-editing tools has allowed scientists to try and target the CCR5 gene in HIV-infected adults.

But no one until now has tried to create children with the resistant genes. In a story first reported by MIT Technology Review, a secretive Chinese project has apparently produced twin girls whose genomes were modified to make them resistant to HIV. It appears as though CRISPR-Cas9 technology was used to delete the CCR5 gene.

Not surprisingly, the experiment has sparked international outrage from scientists and ethicists. Using CRISPR to create so-called designer babies has always topped the list of Don’ts and the scientist who did it is now facing investigation over whether the experiment broke Chinese laws or regulations, according to MIT Technology Review. Meanwhile Feng Zhang, a member of the Broad Institute of MIT and Harvard and the co-inventor of CRISPR, called for a global moratorium on using the technology to create designer babies.

He Jiankui, whose lab performed the procedure on the twins said on a YouTube video that the girls, named Lula and Nana, were conceived using IVF.  Right after the husband’s sperm was added to the eggs the lab added “a little bit of protein and instructions for a gene surgery and removed the doorway that HIV uses to enter cells”, he said, an apparent reference to the CCR5 gene. The procedure was done because the father is HIV positive. Though father-to-child transmission is extremely rare, HE said the father did not want to run the risk of passing on the virus to his daughters.

In an interview with the Associated Press, He said he didn’t just want to be the first to make a gene-edited baby, he wanted to set an example. “Society will decide what to do next,” he said, referring to allowing or forbidding such science.

A lack of scientific data has made it impossible to know for certain if the gene editing worked. In a news story in Nature, genome-editing scientist Fyodor Urnov said the only way to know for sure is to test the girls’ DNA.

But if it turns out to be so, the debate won’t remain within the halls of science for long. For every scientist uncomfortable about overstepping the boundaries of CRISPR etiquette are parents who might view gene editing in a very different light.