Jiankui He defends CCR5 gene editing in embryos

Jiankui He outlined the process and rationale for the genome editing of two human embryos at the International Summit on Human Genome Editing in Hong Kong, including the interest of the parents to implant both embryos despite only one having a successful edit of the CC chemokine receptor 5 (CCR5) gene and an off-target effect in the edited embryo.

Naturally occurring mutations in the CCR5 gene are associated with HIV resistance. He sought to use CRISPR to introduce this mutation into the embryos, rendering the children resistant to HIV infection, because the father of the children was HIV-positive. "It's one of most understood genes," He said at the summit Wednesday...