Gene therapy: where to draw the line

The four classifications of genetic manipulation (somatic cell gene therapy, germ-line gene therapy, enhancement genetic engineering, eugenic genetic engineering) are reviewed from an ethical viewpoint. Immediately, it needs to be recognized that words like "therapy," "enhancement," and "eugenic" already possess an emotional framework, so that careful reasoning is made more difficult. In each of the areas of genetic manipulation, it can be argued that circumstances could be imagined that would either justify or not justify proceeding. Based on our present state of knowledge, the line should be drawn at not carrying out gene therapy of any type except in specific cases that are carefully evaluated in advance. With increased knowledge, the line should be moved to embrace appropriate situations.