A scientist says his group has edited genes in an embryo, a landmark scientific move. The practice is controversial, because it raises the prospect of eugenics.

Columbia University associate professor Dieter Egli says his group has precisely edited genes in an embryo, a landmark scientific move that is highly controversial.

Columbia University associate professor Dieter Egli says his group has precisely edited genes in an embryo, a landmark scientific move that is highly controversial.

Columbia University associate professor Dieter Egli says his group has precisely edited genes in an embryo, a landmark scientific move that is highly controversial.