A new technology aimed at eliminating genetic disease in newborns would combine the DNA of three people, instead of just two, to create a child, potentially redrawing ethical lines for designer babies.

The process works by replacing potentially variant DNA in the unfertilized eggs of a hopeful mother with disease-free genes from a donor. U.S. regulators today will begin weighing whether the procedure, used only in monkeys so far, is safe enough to be tested in humans.

Because the process would change only a small, specific part of genetic code, scientists say a baby would largely retain the physical characteristics of the parents. Still, DNA from all three — mother, father and donor — would remain with the child throughout a lifetime, opening questions about long-term effects for this generation, and potentially the next. Ethicists worry that allowing pre-birth gene manipulation may one day lead to build-to-order designer babies.

‘Once you make this change, if a female arises from the process and goes on to have children, that change is passed on, so it’s forever,” Phil Yeske, chief science officer of the United Mitochondrial Disease Foundation, said by telephone. ‘That’s uncharted territory; we just don’t know what it means. Permanent change of the […]