Evolution of ethical debate about human gene therapy.

Ethical issues generally evolve through four stages: threshold, open conflict, extended debate, and adaptation. The history of the ethical debate on human gene therapy is examined. The threshold was the Nirenberg appeal in 1967. The open conflict centered around two early controversial cases: those of Rogers and Cline. The extended debate has lasted from 1980 to the present, but now adaptation, i.e., a public policy, for somatic cell gene therapy is emerging.