Swedish scientist conducting embryo experiments previously thought to be taboo

A scientific procedure once considered taboo is apparently now being tried in Sweden.

Developmental biologist Fredrik Lanner has started trying to edit the DNA in healthy human embryos, National Public Radio reported. The step makes him the first researcher known to attempt to modify the genes of healthy human embryos.

Lanner is attempting to edit genes in human embryos to learn more about how the genes regulate early embryonic development. He hopes the work could lead to new ways to treat infertility and prevent miscarriages. He also hopes to help scientists learn more about embryonic stem cells so they can someday use them to treat many diseases.

But critics worry that making changes to the DNA in human embryos could accidentally introduce an error into the human gene pool, inadvertently creating a new disease that would be passed down for generations, NPR said.

Lanner, however, says he is initially planning only to study the modified embryos for the first seven days of their growth and would never let them develop past 14 days. The potential benefits could be enormous, he argues.

But not allowing the embryos to survive past two weeks means that the unborn human beings would be created only to be put to death.

NPR visited Lanner and his research team at the Karolinska Institute in Stockholm and watched as they injected a four-cell embryo with a genetic engineering tool known as CRISPR-Cas9.

More to read: Britain Must Not Open Door to Life-Altering, Life-Destroying Science, Ethicists Warn

The gene-editing tool comprises two molecules that can zero in on individual genes and make very precise changes to the DNA. It lets scientists modify DNA much more easily and precisely than ever before. Lanner calls the technique a “game changer.”

Marcy Darnovsky, who heads the Center for Genetics & Society, a watchdog group based in California that supports human embryonic research, cautions that the production of genetically modified human embryos is “quite dangerous.”

“It’s a step toward attempts to produce genetically modified human beings,” Darnovsky said. “This would be reason for grave concern.”

One fear is that scientists could make some kind of mistake, accidentally creating new diseases that would be passed down for generations, said the NPR report.

“When you’re editing the genes of human embryos, that means you’re changing the genes of every cell in the bodies of every offspring, every future generation of that human being,” Darnovsky explained. “So these are permanent and probably irreversible changes that we just don’t know what they would mean.”