Moving Toward Designer Genes

Since scientists first began manipulating genes, they have been envisioning a brave new world in which diseases from Huntington's chorea to sickle-cell anemia to possibly diabetes could be cured simply by inserting the correct strip of DNA into the body's cells. So far, though, most of the genetic tinkering has been limited to transplanting genes into isolated cells in laboratory dishes or into bacteria. But the dawn of designer genes is slowly moving closer. Researchers are now extending their experiments to living animals. In April, scientists at the University of California in Los Angeles reported they had inserted into intact adult mice a gene that makes cells resistant to a specific drug. Last week a team of Yale University scientists announced they had altered an animal's hereditary makeup at a more basic level: by injecting foreign genes into a mouse at its earliest stage of development, a fertilized egg.