The provocative notion of genetically modified babies met the very real world of federal regulation Tuesday, as a government advisory committee began debating a new technique that combines DNA from three people to create embryos free of certain inherited diseases.

The two-day meeting of the Food and Drug Administration panel is focused on a procedure that scientists think could help women who carry DNA mutations for conditions such as blindness and epilepsy. The process would let them have children without passing on those defects.

The debate over whether the technique — nicknamed “three-parent IVF” — should be allowed to proceed to human tests underscores how quickly the science of reproductive medicine is evolving. Scientists argue that this technology, like cloning and embryonic stem cell research, has huge potential to help people. But it is also highly sensitive, touching ethical and political nerves.

The technology involves taking defective mitochondria, the cell’s powerhouses, from a mother’s egg and replacing them with healthy mitochondria from another woman. After being fertilized by the father’s sperm in a lab, the egg would be implanted in the mother, and the pregnancy could progress normally.

The procedure was pioneered by Shoukhrat Mitalipov, a researcher at Oregon Health and Science University who focuses on early embryo development and stem cell biology. He has been able to produce five healthy monkeys using this technique and has proposed testing it in humans.

The FDA’s announcement several months ago that it would hold a public hearing on the subject elicited an outcry from scientists, ethicists and religious groups, who say the technology raises grave safety concerns and could open the door to creating “designer” babies, whose eye color, intelligence and other characteristics are selected by parents.

Marcy Darnovsky, executive director of the Center for Genetics and Society and a vocal critic of the procedure, said human trials would mark the first time the FDA had approved a gene-modification technique whose effect is transmitted to a person’s descendants.

“What we’re talking about is radical experimentation on future children. . . . A decision of such profound magnitude should not be made behind the mostly closed doors of this agency,” Darnovsky told the committee Tuesday.

Advocates of the technology say the discussion has been sensationalized, doing a disservice to women who have mitochondrial diseases and want healthy offspring.

“I don’t think we should be motivated by a fear of the unknown,” said Susan Solomon, chief executive of the New York Stem Cell Foundation, which is working on techniques similar to those of the Oregon researchers.

“There are no designer babies here,” she added. “We are trying to stop a horrible, horrible disease.”

On Tuesday, a number of members of the advisory committee expressed reservations about moving forward with human tests and raised concerns about possible damage to embryos from the procedure and risks to mothers. The FDA often follows the recommendations of its advisory panels but isn’t required to do so.

“There’s overall great concern for the well-being of these kids,” Evan Y. Snyder, the panel’s chairman, said at the meeting, summarizing some of the thoughts of the members. “I think there was a sense of the committee that at this particular point in time, there was probably not enough data either in animals or in vitro to conclusively move on to human trials . . . without answering a few additional questions.”

But he added that the committee thought the research “is incredibly intriguing and in some ways very promising.” The panel is charged with reviewing the procedure’s scientific aspects, not the ethical or social ones.

A different technique that also combined DNA from three parents was used in 2001 on an estimated 30 children. It was deemed a scientific success, at least in the short term, given that researchers did not do any long-term follow-up on the babies. But the idea of “three-parent babies” was so controversial that the FDA told researchers at the time to stop such tests, and since then experiments have been limited to animals.

More than 40 other countries have passed laws or signed treaties banning human genetic modifications that can be inherited. It is a line that governments have been hesitant to cross, but there have been signs recently that such stances may be softening.

A scientific panel in Britain found broad support for such a therapy there, with the caveat that if it is approved, it should be closely monitored and regulated. Parliament is expected to take up the issue this year.

Many of the concerns relate to safety, in part because the impact of tinkering with cells at that level may not be completely evident for years or even generations, said Debra Mathews, assistant director for science programs at the Berman Institute of Bioethics at Johns Hopkins University. She said that she doesn’t oppose this potential treatment but that it should be thoroughly tested and closely regulated.

But there are broader, societal concerns as well.

“There’s a whole other side of the argument that has little to do with safety and a lot more to do with how we think about children and whether we should be in the business of genetically modifying generations at all,” Mathews said.