An influential US science advisory committee this week said genetic modification of human embryos should be allowed in the future to eliminate diseases, sparking new debate on this controversial topic.
The report by the National Academy of Sciences (NAS) caused concern among some researchers who fear that genetic tools could be used to boost certain people's intelligence or create people with particular physical traits.
"Clinical trials for genome editing of the human germline - adding, removing or replacing DNA base pairs in gametes or early embryos - could be permitted in the future," said the report, released Tuesday.
"But only," it added, "for serious conditions under stringent oversight."
The emergence of inexpensive and accurate gene-editing technology, known as CRISPR/Cas9, has fueled "an explosion of new research opportunities and potential clinical applications, both heritable and nonheritable, to address a wide range of human health issues," the report said.
The committee of international experts was convened to examine scientific, ethical and governance issues surrounding human genome editing.
The experts noted that clinical trials on gene editing for certain nonhereditary traits are already under way.
"These therapies affect only the patient, not any offspring, and should continue for treatment and prevention of disease and disability, using the existing ethical norms and regulatory framework for development of gene therapy," it said.
The group said using science to enhance human traits, such as physical strength, "should not be allowed at this time, and that broad public input and discussion should be solicited before allowing clinical trials for somatic genome editing for any purpose other than treating or preventing disease or disability."
In 2015, the United Nations Educational, Scientific and Cultural Organization (UNESCO) International Bioethics Committee called for a halt to human germline editing, out of concern that the technique could lead to a resurgence of eugenics, or attempts to improve the genetic quality of the human race.
More than 40 countries have signed an international convention banning the use of gene-editing to modify the human race.
In the United States, federal funds cannot be used for editing DNA and human reproductive cells.
"The concept of altering the human germline in embryos for clinical purposes has been debated over many years from many different perspectives, and has been viewed almost universally as a line that should not be crossed," said a 2015 statement from National institutes of Health Director Francis Collins.
Reacting to the new report, some experts said that times are changing rapidly, and that the NAS aims to advance discussion of the science while ensuring ethical oversight of what could be a promising technology.
The report "now takes this debate an important step further," said Bruce Whitelaw, professor of animal biotechnology at the University of Edinburgh.
"It is a triumph of applying caution -- with the report detailing stringent, overarching principles that should be followed -- over premature prohibition of what is an exciting technology for society."