By Scott McCredie for MSN Health & Fitness
Freelance
It started a decade ago with Dolly the Scottish sheep, the world’s first cloned mammal.
Then a year later came Lucy the Canadian mouse, the first mammal with artificially implanted genes that could be inherited by her offspring. Since then, the world has expressed a mixture of confusion, horror and optimism at the potential of genetic engineering to prevent diseases in humans and “enhance” physical or cognitive traits.
So where does this technology stand? Are we any closer to creating so-called “designer babies”?
And is there a developing darker side in which parents intentionally alter a baby’s genetic makeup so he has the same condition, such as deafness or dwarfism, as his parents?
If the last question shocks you, be clear that a survey published by the medical journal Fertility and Sterility showed that about 3 percent of U.S. fertility clinics—four out of 137 responding clinics that perform embryo screening—already have performed procedures to help couples create children with a disability such as dwarfism or deafness.
First, a few definitions are needed. According to Marcy Darnovsky, associate director of the Center for Genetics and Society, in Oakland, Calif., when people say “designer baby” they often mean different things. Some refer to the ability to select the sex of an embryo; others interpret it as selecting the embryo (fertilized egg) itself. Embryo selection is increasingly used for in vitro procedures when couples are at high risk for certain genetic diseases, such as cystic fibrosis. It allows them to screen out embryos carrying genes associated with the disease.
Most scientists avoid the “designer baby” phrase altogether, preferring “germline engineering” or inheritable genetic modification (IGM), defined as the altering of genes that pass on to future generations. This contrasts with non-inheritable gene therapy, such as when altered genes are added to body tissue, say, a diseased lung, in efforts to improve function.
</IMG>More Reality Than Science Fiction
Although the technology for doing IGM has existed since 1978, it is now only done in non-human animals. If a scientist, for example, wanted to test a new anti-cholesterol drug on mice, rather than trying to find mice with naturally high levels of cholesterol, he could order a line of mice whose genes had been changed to give them this condition. As of yet, however, the technology hasn’t been perfected. Mistakes often are made in the gene-altering process that lead to developmental abnormalities. This is one reason—and a good one at that—the technology hasn’t been attempted in humans.
But some people advocate developing IGM for use in humans. They see IGM as a way to make life better for their children. And what parent wouldn’t want that?
“None of us want to pass on to our children lethal genes if we can prevent it,” says W. French Anderson, professor of biochemistry and pediatrics at the University of Southern California School of Medicine. “And that's what's going to drive germline gene therapy.”
But this kind of argument is a little misleading, says Darnovsky. The technology already exists today for screening out embryos with “lethal” genes, without adding to or changing the genes of a future child. The technique used for this is called pre-implantation genetic diagnosis. Like in vitro fertilization (for infertile couples), it involves removing several eggs from a woman, fertilizing them with the husband’s sperm, and allowing the embryos to grow to several cells each. Then one cell is extracted from each and genetically analyzed. As scientists continue to unravel the code of the human genome, genes associated with other diseases and other traits will be identified.
Freelance
It started a decade ago with Dolly the Scottish sheep, the world’s first cloned mammal.
Then a year later came Lucy the Canadian mouse, the first mammal with artificially implanted genes that could be inherited by her offspring. Since then, the world has expressed a mixture of confusion, horror and optimism at the potential of genetic engineering to prevent diseases in humans and “enhance” physical or cognitive traits.
So where does this technology stand? Are we any closer to creating so-called “designer babies”?
And is there a developing darker side in which parents intentionally alter a baby’s genetic makeup so he has the same condition, such as deafness or dwarfism, as his parents?
If the last question shocks you, be clear that a survey published by the medical journal Fertility and Sterility showed that about 3 percent of U.S. fertility clinics—four out of 137 responding clinics that perform embryo screening—already have performed procedures to help couples create children with a disability such as dwarfism or deafness.
First, a few definitions are needed. According to Marcy Darnovsky, associate director of the Center for Genetics and Society, in Oakland, Calif., when people say “designer baby” they often mean different things. Some refer to the ability to select the sex of an embryo; others interpret it as selecting the embryo (fertilized egg) itself. Embryo selection is increasingly used for in vitro procedures when couples are at high risk for certain genetic diseases, such as cystic fibrosis. It allows them to screen out embryos carrying genes associated with the disease.
Most scientists avoid the “designer baby” phrase altogether, preferring “germline engineering” or inheritable genetic modification (IGM), defined as the altering of genes that pass on to future generations. This contrasts with non-inheritable gene therapy, such as when altered genes are added to body tissue, say, a diseased lung, in efforts to improve function.
</IMG>More Reality Than Science FictionAlthough the technology for doing IGM has existed since 1978, it is now only done in non-human animals. If a scientist, for example, wanted to test a new anti-cholesterol drug on mice, rather than trying to find mice with naturally high levels of cholesterol, he could order a line of mice whose genes had been changed to give them this condition. As of yet, however, the technology hasn’t been perfected. Mistakes often are made in the gene-altering process that lead to developmental abnormalities. This is one reason—and a good one at that—the technology hasn’t been attempted in humans.
But some people advocate developing IGM for use in humans. They see IGM as a way to make life better for their children. And what parent wouldn’t want that?
“None of us want to pass on to our children lethal genes if we can prevent it,” says W. French Anderson, professor of biochemistry and pediatrics at the University of Southern California School of Medicine. “And that's what's going to drive germline gene therapy.”
But this kind of argument is a little misleading, says Darnovsky. The technology already exists today for screening out embryos with “lethal” genes, without adding to or changing the genes of a future child. The technique used for this is called pre-implantation genetic diagnosis. Like in vitro fertilization (for infertile couples), it involves removing several eggs from a woman, fertilizing them with the husband’s sperm, and allowing the embryos to grow to several cells each. Then one cell is extracted from each and genetically analyzed. As scientists continue to unravel the code of the human genome, genes associated with other diseases and other traits will be identified.
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