World's first `three-parent baby" born in Mexico

The 5-month-old boy's mother carries genes for Leigh syndrome, a fatal disorder of the developing nervous system. The diseaseis caused by faulty genes in the mitochondria, "batteries" that energise human cells and are inherited from the mother, the magazine reported.

The Jordanian mother was healthy, but her two earlier children both died of Leigh syndrome, and a team led by John Zhang at New York's New Hope Fertility Centre agreed to help the couple by taking DNA from a second woman, using a technique known as mitochondrial DNA transfer.

The procedure, currently legal only in Britain, involves removing a tiny amount of faulty DNA from a mother's egg and replacing it with DNA from a second woman.

It is known as "three-parent baby" technology because a child born following the procedure would have DNA from two women and one man.

"The method approved in the UK is called pronuclear transfer and involves fertilizing both the mother's egg and a donor egg with the father's sperm," New Scientist said.

Before the fertilized eggs split into early-stage embryos, each nucleus is removed and the nucleus of the donor's egg is discarded and replaced by the one from the mother's fertilized egg.

"But this technique wasn't appropriate for the couple - as Muslims, they were opposed to the destruction of two embryos," the magazine said. "So Zhang took a different approach, called spindle nuclear transfer."

Zhang's team replaced the nucleus of a donor's egg with a nucleus from the mother, and then fertilized this with the father's sperm.

They used the technique to create five embryos, one of which developed normally after implanting in the mother's uterus, it said.

The work was carried out in Mexico because "there are no rules"there, and no form of mitochondrial DNA transfer has been legalized in the United States, Zhang told the magazine.
- DPA