On June 1, an international group of industry and academic collaborators, led by geneticist Dieter Egli at Columbia University, released a preprint on bioRxiv demonstrating the use of base editing in human embryos (2026, DOI: 10.64898/2026.05.30.728989).
Base editing, which allows for precise swapping of one nucleotide for another without creating destructive double-strand breaks in DNA, is an evolution of CRISPR gene editing technology.
Although the base editing didn’t result in aneuploidy, it still had significant off-target effects. The researchers observed editing at sites other than the gene of interest and cases of mosaic embryos, in which not all the cells in the embryo carry the gene edits. For those reasons, the authors argue, more work and ethics discussions are necessary before using genetically edited embryos for clinical in vitro fertilization (IVF).
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[David] Barrett has a few blunt words to spare for those who see genetic editing of embryos just beyond the horizon: “Science is not ready for heritable human genome editing.”

