GENEVA (AP) — The chief of the World Health Organization says his agency is assembling experts to consider the health impacts of gene editing.

WHO Director-General Tedros Adhanom Ghebreyesus said Monday that gene editing "cannot be just done without clear guidelines" and experts should "start from a clean sheet and check everything."

Tedros' comments followed Chinese scientist He Jiankui's announcement last week that he had helped alter the DNA of newborn twins in hopes of making them resistant to the AIDS virus.

China ordered a halt to experiments by He's team.

Tedros told reporters WHO's experts "should start from asking, 'Should we even consider this?'" and noted: "We have a big part of our population who say, 'Don't touch.'"

He said: "We have to be very, very careful, and the working group will do that."