Overview
- A Nature paper published Thursday, June 25, 2026, reports that researchers led by Kathy Niakan used adenine base editing (ABE8e) to disable the gene NANOG in donated human embryos and found NANOG is essential for forming the epiblast cells that give rise to the fetus.
- The team applied base editing at fertilization to make a precise splice-site change that functionally knocked out NANOG, and the edited embryos developed supporting tissues instead of a pluripotent epiblast.
- Base editing avoided the double-strand DNA breaks linked to large-scale genome damage seen with earlier CRISPR–Cas9 methods, but many embryos were mosaic (containing both edited and unedited cells) and showed unintended nearby, or bystander, edits.
- The work was done with HFEA approval and informed donor consent in the UK and is framed as basic research, while critics including the ASGCT reiterate calls for moratorium-style limits on any heritable embryo editing.
- The findings advance knowledge of human embryology and stem-cell biology and may help improve IVF or lab models, but persistent mosaicism, bystander mutations and unresolved ethical and regulatory questions mean clinical use remains off the table.