Medicine: Green Light

Scientists stand on the brink of performing gene therapy

The goal is grand -- and maddeningly difficult to achieve. Ever since Watson and Crick first deciphered the structure of DNA in 1953, doctors have had visions of treating disease not from the outside, with drugs or scalpels, but from the inside, by altering the primal instructions tucked in the nucleus of living cells.

Now, after years of debate about the ethics of genetic engineering and lengthy tests in animals, the first human trials are about to begin. Last week two experimental techniques passed a major regulatory hurdle, winning approval from the National Institutes of Health's Recombinant DNA Advisory Committee. The...