Researchers identify gene that starts human embryo formation

Researchers have identified a gene whose activation begins the process that turns cells in a fertilized human egg into an embryo. The gene, called NANOG, was studied by altering its function in eggs donated by women undergoing IVF treatment. The team applied a precise gene-editing method known as CRISPR base editing, which changes one DNA letter at a time.

When NANOG was disabled in human eggs, none of the resulting cells developed into those that form the embryo proper.

The new experiments found that its role in people differs from its role in mice: disabling the gene in mouse eggs prevented yolk-sac formation, while the same change in human eggs blocked embryo-cell formation. The edited human embryos still looked normal under a microscope.

Selection of embryos for IVF transfer currently relies mainly on visual appearance, which does not always predict successful implantation.

limits Base editing was performed by injecting the editing components into eggs at the same time as sperm. This approach lowered but did not eliminate mosaicism, in which only some cells carry the intended edit. The study was published in the journal Nature. The authors note that the technique remains far from clinical use for creating gene-edited children.