Gene Tests Allow Disease-Free Baby
Date accessed: 22 June 2001
By Rick Weiss
Washington Post Staff Writer
Saturday, June 9, 2001; Page A04
Doctors for the first time have used genetic tests to identify human embryos
that lack a key cancer-causing mutation, helping a New York couple to give birth
to a baby free of the childhood cancer syndrome that had run in the father's
family. The work is the latest in a series of recent developments that have allowed
couples to screen their test-tube embryos for the presence or absence of disease
genes, then transfer only the healthy embryos to the mother's womb. The technology has freed a growing number of families from the ancestral
chains of inherited illness, but it has also raised fears that parents may soon
be able to choose from a menu of less-pressing genetic traits, heralding an age
of "designer babies." The latest work plays into that controversy
because it screened out embryos with a gene variation that, while adding to the
risk of cancer, is not 100 percent certain to cause disease. Some experts said
that while many embryo tests seemed justifiable, they were worried by the
field's direction. Yury Verlinsky and colleagues at the Reproductive Genetics Institute in
Chicago used a molecular testing technique called preimplantation genetic
diagnosis, or PGD, to screen test-tube embryos produced by the New York couple,
who asked to remain anonymous. The technique involves the harmless removal of
one cell from an eight-cell embryo for genetic testing. The father has Li-Fraumeni syndrome, a genetic condition caused by a mutation
in the p53 gene. People with the syndrome have about a 50 percent chance of
getting any of several types of cancer by age 40, and an 80 percent to 90
percent lifetime cancer risk -- about double the standard 40 percent risk.
Because of the defect, which he inherited from a parent, the man had developed
cancer at age 2 and again at age 31. Seven embryos out of 18 produced by the couple tested negative for the
defect. A total of three were transferred in two efforts, and one, a boy,
survived to term and was born last fall. Details of the work -- the first to
screen embryos for a p53 mutation -- are described in the March issue of
Reproductive BioMedicine Online and were presented Thursday at a Chicago news
conference. Verlinsky said he believes the technology should be used only to avoid
illnesses. But he conceded that the line can be fuzzy when, as in the case of
Li-Fraumeni, disease is not 100 percent certain to occur. In all cases, he said,
the decision of whether to test should be up to the doctor and the patient. "Government regulations always backfire," he said. In England, he
said, where PGD is regulated, "in three years they've done about as much as
I do in one month."
Category: 32. Genome Project and Genomics