Monkey Business

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Even if the new gene has indeed made it into ANDi's reproductive cells--which can't be known until he reaches sexual maturity in four or five years--there are plenty of hurdles to creating useful research monkeys. Scientists still must learn to substitute a malfunctioning gene for the animal's healthy version, then hope the gene expresses its protein at the right time, in the right place and in the right amount to mimic human disease. For diseases involving the misbehavior of several genes, the difficulties will only be compounded. "These techniques are really in their infancy compared to what we can do with the mouse," says Schatten.

For animal-rights activists, the leap from mouse to monkey will be a red flag. More broadly troubling, ANDi's success also raises the specter of human-germline gene engineering--that is, altering people's basic DNA so that any changes are passed on to their offspring. This sort of genetic tinkering, which could ultimately lead to "designer babies," artificially enhanced to be healthier, smarter or even more attractive, is currently far beyond our expertise. Nobody is likely to try to play God with humans in this way for decades.

In part that's because, as ANDi's case proves, it's very difficult and expensive to do, and because the unexpected side effects of gene transfers will be hard to predict. Indeed, even conventional gene therapy, which doesn't change the basic germline, has become controversial since the death of Jesse Gelsinger in a gene-therapy trial at the University of Pennsylvania last year. Besides, scientists have much simpler ways to stave off at least some genetic diseases. Parents whose embryos have the gene for Tay-Sachs disease, for example, can test for that defect and never bring the embryo to term.

But the ability to replace faulty genes directly--or even add enhanced genes--and then have those changes passed on to one's descendants will eventually come. When it does, say ethicists, we'd better have policies in place to deal with it. Germline gene manipulation shouldn't necessarily be banned, says Jeffrey Kahn, director of the Center for Bioethics at the University of Minnesota. But, he adds, "I think it's important to have this discussion now, when we have time to think about the implications."