A doctor who treats infertility in New York City says he has helped a couple have the first baby purposefully created with DNA from three different adults.
John Zhang of the New Hope Fertility Center in Manhattan traveled to Mexico earlier this year to perform a procedure for a couple from Jordan that enabled them to have the baby in May, according to a clinic spokesman.
Zhang performed the procedure in the hopes of helping the couple, who the clinic declined to identify, have a healthy baby. The couple had lost their first two children to Leigh syndrome, an inherited neurological disorder.
The idea of creating babies this way to help prospective parents who come from families plagued by genetic disorders has long been controversial. In February, a 12-member panel assembled by the National Academies of Sciences, Engineering and Medicine outlined a plan for how scientists could ethically pursue the research.
The Food and Drug Administration had requested the report after two other groups of U.S. scientists asked for permission to try. Despite the report, the FDA said Congress had prohibited the agency from allowing the procedure. In response to the latest development, the FDA reiterated that position in an email to NPR.
That prohibition had prompted Zhang to travel to Mexico, according to the clinic.
The baby's birth prompted both praise and criticism. Some infertility experts welcomed the development as a potentially important step for women carrying genetic disorders.
Zhang plans to present the details of the case at the society's meeting next month in Salt Lake City.
Some scientists said the move was irresponsible because not enough research had been done to know whether it was safe.
"This is a troubling development on a number of levels," wrote Paul Knoepfler, a cell biologist at the University of California, Davis, in an email to NPR. "It could have gone wrong in any number of ways and still could."
Others fear the move could open the door to the creation of so-called designer babies, in which parents try to pick and choose the traits of their children.
"This is entrepreneurial reproductive technology at its most unethical and irresponsible," wrote David King, who heads the genetic watchdog group Human Genetics Alert in London, in an email. "When are the world's governments going to stop rogue scientists crossing crucial ethical lines?"
One scientist hoping to perform this procedure in the United States is worried about details he has seen in Zhang's presentation.
"While exciting, there appears to be problems with the study," wrote Dieter Egli of Columbia University Medical Center in an email. Egli said he sees possible abnormalities in the embryos Zhang created, which he says reinforces why the FDA should be overseeing such experiments.
"For a technique pioneered and developed in the U.S., it be fitting to see the benefits to patients here as well," he says. "Because of funding restrictions to the FDA, promising medical advances are forced to move elsewhere."
The birth of the child was first reported Tuesday by the British magazine New Scientist. A clinic spokesman who asked not to be named told NPR that most of the details in the article were accurate except statements that the baby was born in Mexico and there was no oversight of the procedure there.
Leigh syndrome is known as a mitochondrial disorder because it is caused by defects in a type of DNA known as mitochondrial DNA. Mitochondria are structures in cells that provide the cells with energy.
To help women who carry defects in mitochondrial DNA, scientists have developed techniques to replace the defective mitochondrial DNA with healthy DNA.
The technique Zhang used involved removing all the DNA from the nucleus of eggs donated by women with healthy mitochondrial DNA. The DNA in the nucleus of eggs carries most of the genetic information needed to create a person, including the information most people consider important, such as determining an individual's physical appearance.
Zhang then removed all the nuclear DNA from the eggs of the woman trying to have a healthy baby and placed that DNA into the donor egg, leaving the defective mitochondrial DNA behind. Those eggs, which then presumably had only healthy DNA, were then fertilized with sperm from the husband of the woman trying to have a baby.
Zhang created five embryos this way. Only one developed normally, according to his report. It was transferred into the woman's womb and resulted in the birth of a boy, who appears healthy, according to the clinic.
Because mitochondrial DNA is only passed from women to their offspring, the boy is incapable of transferring the mitochondrial DNA to any future children, sidestepping many of the ethical concerns.
A previous version of this story incorrectly said women pass mitochondrial DNA only to female offspring, rather than to all offspring.