David Cyranosky and Heidi Ledford in Nature:
A Chinese scientist claims to have helped make the world’s first genome-edited babies — twin girls, who were born this month. The announcement has provoked shock and outrage among scientists around the world. He Jiankui, a genome-editing researcher at the Southern University of Science and Technology of China in Shenzhen, says that he impregnated a woman with embryos that had been edited to disable the genetic pathway HIV uses to infect cells. In a video posted to YouTube, He says the girls are healthy and now at home with their parents. Sequencing of the babies’ DNA has shown that the editing worked, and altered only the target gene, he says. The scientist’s claims have not been verified through independent genome testing, nor published in a peer-reviewed journal. But, if true, the twins’ birth would represent a significant — and controversial — leap in the use of genome editing. Until now, the use of these tools in embryos has been limited to research, often to investigate the benefit of using the technology to eliminate disease-causing mutations from the human germ line. But some studies have reported off-target effects, raising significant safety concerns.
HIV’s entry point
Documents posted on China’s clinical-trial registry show that He used the popular CRISPR–Cas9 genome-editing tool to disable a gene called CCR5, which encodes a protein that allows HIV to enter a cell. Genome-editing scientist Fyodor Urnov was asked to review documents that described DNA sequence analysis of human embryos and fetuses edited at the CCR5 locus for an article in MIT Technology Review. “The data I reviewed are consistent with the fact that the editing has, in fact, taken place,” says Urnov, who is based at the Altius Institute for Biomedical Sciences in Seattle, Washington. But he adds that the only way to tell whether the children’s genomes have been edited is to independently test their DNA.