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New Fertility Treatment Swaps Nuclei of Fertile, Defective Eggs

By Denise Grady

The New York Times -- Doctors in China have become the first in the world to make an infertile woman pregnant with an experimental technique devised in the United States for women who have healthy genes but defects in their eggs that prevent embryos from developing.

The technique, called nuclear transfer, involves removing the nucleus, which contains the genetic material, from a woman’s fertilized egg and transferring it to an egg of a woman whose own nucleus has been removed. The resulting hybrid egg is then put back into the womb of the first woman. The idea is that the second woman’s egg will provide a healthier environment for the genes.

Although researchers at Sun Yat-sen University in Guangzhou succeeded last year in impregnating a 30-year-old woman with the technique, she gave birth prematurely and the fetuses died. Although the procedure was legal at the time in China, it was recently banned there.

Critics say the technique is perilously close to human cloning, which has been widely condemned, although there is no proof it has ever been done or even seriously attempted. Those who oppose nuclear transfer also argue that it poses unknown hazards to any children who may be born as a result, and as evidence they cite the death of the Chinese woman’s fetuses.

Doctors involved in the research say it is not cloning, but is an attempt to give infertile women chances to have children that are genetically their own. They say that the technique has been studied extensively in mice and is safe and effective.

A report on the experiment in China is to be presented on Tuesday at a medical conference in San Antonio. It was described in The Wall Street Journal on Monday.

Nuclear transfer is quite similar to a crucial step in cloning, but it also differs in important ways.

To make a clone like Dolly the sheep researchers start with a fertilized egg and remove its nucleus. Then, they replace the nucleus with a cell from an adult animal, electrically stimulate the egg to start its development and implant it in the prospective mother’s womb.