Manipulating the Human Genome

New genetic technologies allow scientists to delete a mutant gene and insert a healthy one, which someday may enable doctors to banish disease genes. Used in embryos, gene editing has the potential to eliminate inherited diseases, such as cystic fibrosis. Until recently, the techniques have been used only on embryos from laboratory animals. In April, however, stunned scientists accused Chinese researchers of crossing a strict ethical boundary by using the technology on human embryos — albeit nonviable ones. Some ethicists and scientists fear that if the new genetic engineering techniques are used to alter viable human embryos, scientists would then begin creating “designer babies.” The Chinese experiment raised fears that the notorious eugenics movement of the early 20th century — aimed at creating a perfect “master race” — might re-emerge. Twenty-nine countries — but not the United States — prohibit genetic manipulation of human embryos, and ethicists and scientists are calling for a worldwide ban or moratorium until such procedures are better understood.