A U.S. advisory board on Wednesday debated a controversial new technique that would use DNA from three people to produce embryos free of a particular type of hereditary disease.
The panel, which provides independent advice to the Food and Drug Administration, weighed whether a procedure that replaces part of a human egg cell with that of another is safe for clinical trials.
The procedure has thus far been tested only on monkey embryos.
Proponents of the technique called "three-parent in vitro fertilization" say the measure has huge medical potential while detractors say it could lead to custom-made "designer babies."
At the center of debate lie mitochondria, a structure where most of a cell's energy is created, that also contains DNA separate from the 23 chromosomes in a cell's nucleus.
Each year some 1,000 to 4,000 children born in the United States develop mitochondrial diseases, which often affect the central nervous system or cause blindness or heart problems.
The diseases, which generally become evident before age ten, often result from genetic abnormalities in mitochondria, which are passed down from a child's mother.
Under the procedure, a disease-producing mitochondria in an egg is replaced with another woman's mitochondria, before the egg is then fertilized in a laboratory and implanted in the mother.
Shoukhrat Mitalipov, the scientist at Oregon Health and Science University who created the procedure, successfully oversaw the birth of five monkeys using the technique.
He would now like to pursue clinical trials on humans.
In 2001, using a different technique, U.S. scientists carried out successful three-parent fertilization experiments which resulted in the birth of some 20 children.
But the FDA asked them to halt the procedure on humans.
The Center for Genetics and Society, a Washington group opposed to the procedure, organized a petition against its approval.
"This is a biologically extreme procedure that puts any resulting children at serious risk, and that breaks a long-standing international consensus against producing genetically engineered humans" said director Marcy Darnovsky.
"The technique ... raises grave safety and social concerns. It carries a wide range of predictable and unpredictable risks for any resulting children and for future generations," she said.
Some 40 countries, including many with large biotechnology and advanced biomedical sectors, have adopted laws forbidding similar genetic modifications, Darnovsky emphasized.
Susan Solomon, CEO of the New York Stem Cell foundation told The Washington Post that people's feelings on the procedure should not be motivated by a fear of the unknown.
"There are no designer babies here," she said. "We are trying to stop a horrible, horrible disease."