CRISPR Base Editing Study Shows NANOG Is Required for Human Embryo Cell Formation

Researchers at the University of Cambridge disabled the NANOG gene in fertilized human eggs and observed that none of the resulting cells developed into those that form the embryo proper. The work relied on CRISPR base editing, which alters one DNA letter at a time rather than cutting strands.

Kathy Niakan, who led the team, said the activation of NANOG starts the developmental program that produces cells forming a human body.

When the same edit was performed in mouse eggs, cells failed to become yolk sac progenitors instead. The study marks the first use of CRISPR base editing to examine gene function in healthy human embryos. Earlier base-editing work in 2017 used only abnormal embryos discarded after IVF, and a June 2026 preprint from Dieter Egli at Columbia University focused on correcting disease mutations rather than basic gene roles.

Niakan’s team injected the editing components into eggs together with sperm, which lowered mosaicism to 50 percent. One edit attempted by Egli’s group produced 80 percent mosaicism. Robin Lovell-Badge of the Francis Crick Institute noted that even 50 percent mosaicism would remain too high for correcting disease-causing variants.

Mary Herbert, a member of the Cambridge team now at Monash University, stated that the technology is not ready for creating gene-edited children. Niakan said it would be unethical to attempt such edits now but called for continued basic research that is publicly discussed.

The paper appeared in Nature with the DOI 10.1038/s41586-026-10792-1 and was amended on 26 June 2026 to correct the description of Egli’s views.