Medicine: An Early-Warning System

For many would-be parents, the recent revolution in prenatal genetic testing has created agonizing dilemmas. If the tests reveal genetic abnormalities in the fetus, the mother and father must either have a handicapped child or resort to abortion. At best the choice is painful. For some, it is the worst kind of moral quandary.

Now a team of medical researchers has devised a technique that may eventually help parents sidestep this predicament. Scientists at the Illinois Masonic Medical Center and Northwestern University, led by geneticist Yury Verlinsky, say they can test for genetic defects in the human egg even before it...