The Download: three-person babies, and tracking "AI readiness" in the US

Eight babies have been born in the UK thanks to a technology that uses DNA from three people: the two biological parents plus a third person who supplies healthy mitochondrial DNA. The babies were born to mothers who carry genes for mitochondrial diseases and risked passing on severe disorders. In the team's approach, patients' eggs are fertilized with sperm, and the DNA-containing nuclei of those cells are transferred into donated fertilized eggs that have had their own nuclei removed. The new embryos contain the DNA of the intended parents along with a tiny fraction of mitochondrial DNA from the donor, floating in the embryos' cytoplasm. The study, which makes use of a technology called mitochondrial donation, has been described as a "tour de force" and "a remarkable accomplishment" by others in the field. But not everyone sees the trial as a resounding success.