A group of leading biologists on Thursday called for a worldwide moratorium on use of a new genome-editing technique that would alter human DNA in a way that can be inherited.

The biologists fear that the new technique is so effective and easy to use that some physicians may push ahead before its safety can be assessed. They also want the public to understand the ethical issues surrounding the technique, which could be used to cure genetic diseases, but also to enhance qualities like beauty or intelligence. The latter is a path that many ethicists believe should never be taken.

“You could exert control over human heredity with this technique, and that is why we are raising the issue,” said David Baltimore, a former president of the California Institute of Technology and a member of the group whose paper on the topic was published in the journal Science.

Ethicists, for decades, have been concerned about the dangers of altering the human germline--meaning to make changes to human sperm, eggs or embryos that will last through the life of the individual and be passed on to future generations. Until now, these worries have been theoretical. But a technique invented in 2012 makes it possible to edit the genome precisely and with much greater ease. The technique has already been used to edit the genomes of mice, rats and monkeys, and few doubt that it would work the same way in people.

The technique holds the power to repair or enhance any human gene. “It raises the most fundamental of issues about how we are going to view our humanity in the future and whether we are going to take the dramatic step of modifying our own germline and in a sense take control of our genetic destiny, which raises enormous peril for humanity,” said George Q. Daley, a stem cell expert at Boston Children’s Hospital and a member of the group.

The biologists writing in Science support continuing laboratory research with the technique, and few if any scientists believe it is ready for clinical use. Any such use is tightly regulated in the United States and Europe. American scientists, for instance, would have to present a plan to treat genetic diseases in the human germline to the Food and Drug Administration.

The paper’s authors, however, are concerned about countries that have less regulation in science. They urge that “scientists should avoid even attempting, in lax jurisdictions, germline genome modification for clinical application in humans” until the full implications “are discussed among scientific and governmental organizations.”

Scientists also say that replacing a defective gene with a normal one may seem entirely harmless but perhaps would not be.

“We worry about people making changes without the knowledge of what those changes mean in terms of the overall genome,” Dr. Baltimore said. “I personally think we are just not smart enough--and won’t be for a very long time--to feel comfortable about the consequences of changing heredity, even in a single individual.”

The International Society for Stem Cell Research said Thursday that it supported the proposed moratorium.

The Doudna group calls for public discussion, but is also working to develop some more formal process, such as an international meeting convened by the National Academy of Sciences, to establish guidelines for human use of the genome-editing technique.

“We need some principled agreement that we want to enhance humans in this way or we don’t,” Dr. Jaenisch said. “You have to have this discussion because people are gearing up to do this.”