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Tuesday, October 14, 2003The doctor, Jamie Grifo of New York University School of Medicine, first tried a variant of the technique in the United States about five years ago, when he transplanted a woman's genes from her own egg cells into the gutted egg cells of a younger woman. The rationale is that some women may be infertile not because of defects in their DNA but because of problems with the fluid surrounding the DNA in their eggs. That fluid, called cytoplasm, contains the egg cells' energy powerhouses, or mitochondria, and chemicals that nurture the cell and its genes. The idea, in effect, is to construct new eggs that have the infertile woman's DNA but the cytoplasm of a young, healthy woman -- then fertilize that egg with sperm from the woman's husband. When Grifo described those efforts in October 1998 at the annual meeting of the American Society for Reproductive Medicine (ASRM), the FDA took note and determined that the procedure fell under the same regulations as human cloning, because both involve transfers of DNA from one cell to another. The agency warned Grifo against trying it again without FDA permission. They also apparently wanted him to make sure it was safe before using it on people: In an interview about two years ago with The Washington Post, he complained vehemently that the agency had wanted him to conduct experiments on animals before trying his approach again with women. And it looks as if the FDA was right to be concerned: Five of those reconstructed zygotes were transferred to the infertile woman's womb, where three successfully implanted. After a month, heartbeats could be detected in all three, but one fetus was surgically killed to improve the odds of survival for the other two. At 24 weeks, one fetus was delivered prematurely because of ruptured membranes and died of "respiratory distress." The other was delivered dead at 29 weeks. The fetuses' cells contained a mix of DNA from the infertile woman and the fertile woman who had donated her eggs. Specifically, the fetuses' cells contained "nuclear DNA" (the main batch of genes) from the infertile couple as planned, but also "mitochondrial genes" (which reside in the cytoplasm) from the fertile woman who donated the egg. Scientists are not sure whether such mixtures of genes from two mothers can cause developmental problems, but that possibility has been noted by the FDA as one reason to proceed cautiously with such techniques. Sounds like the FDA's concerns were limited more to safety than to whether or not this was cloning. And they're right to be concerned. We don't know what kind of consequences manipulating genetic material can have. It's rather cruel to subject an infertile couple to an experimental technique that could result in a deformed baby - or in this case a dead one. Not to mention the cruelty to the child whose genes have been manipulated. You could argue that the parents know the risks and are willing to take them, but without any trials in other animals, they really don't know the risks. posted by Sydney on 10/14/2003 07:56:00 AM 0 comments 0 Comments: |
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