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Choosing a Perfect Child
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10828 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
3 / 1993 |
2,413 Words |
| Author
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Ricki Lewis
Ricki Lewis is the author of two college textbooks, Human
Genetics: Concepts and Applications and Life (1997, 1998,
McGraw-Hill College Publishing, Dubuque, Iowa), and coauthor
of two anatomy and physiology textbooks. She has published
more than 2,500 articles in popular magazines and journals. |
Chloe O'Brien, who celebrates her first birthday this month, is a very wanted child, perhaps more so than most. When she was a mere ball of cells, smaller than the smallest speck of sand, a test determined that she would be free of the cystic fibrosis genes that each of her parents carries. Chloe-to-be, along with another ball of cells (a potential twin), was implanted into her mother's uterus. Only one of the two balls of cells, Chloe-to-be, survived the rigors of prenatal development, and Chloe today is a healthy little girl.
The O'Briens had already had a child who suffered from the stiflingly thick mucus clogging the lungs that is a hallmark of cystic fibrosis, the most common genetic disease among Caucasians. They wanted to spare their future children this fate--but they also wanted to avoid having to end a pregnancy that would yield an affected child.
"Previously, couples had to wait from 9 to 15 weeks [after conception] to find out if their developing baby was affected by a known genetic disease. Now, we can diagnose these inherited diseases within three days after an egg is fertilized in the laboratory, before it is transferred back to the woman," says Mark Hughes of the Baylor College of Medicine in Houston. Hughes, along with John Lesko, also of Baylor, and Alan Handyside, Robert Winston, and Juan Tarin, of Hammersmith Hospital in London, reported the preimplantation diagnosis of cystic fibrosis in September 1992 in the New England Journal of Medicine.
The preimplantation genetic diagnosis that confirmed Chloe to be free of the cystic fibrosis genesis built primarily on three existing technologies: in vitro fertilization (IVF); gene amplification, a way to rapidly copy a single gene from a single cell; and gene probing, which detects the gene responsible for the disorder. The latter two interventions are performed on the 8-cell "preembryo" [see "Before the Embryo, p. XXX].
Few couples have so far had their preembryos examined for genetic problems, and the high costs of the procedure will likely keep the numbers down. However, with the rapid progress being made by the Human Genome Project in identifying genes associated with specific genetic disorders, preembryos in the future may be scrutinized for a wider range of diseases, from rare inherited ailments to the more common heart disease and cancer.
Is a brave new world of mechanized reproduction upon us? To understand how we may someday pick and choose the traits of
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