Introduction

In the late 1960s and early 1970s, there was considerable debate about the ethics of research involving the genetic modification of humans by inserting, repairing, or deleting genes. Opponents of gene transfer research argued that genetic interventions were dangerously different from other therapeutic interventions, while the proponents of such research insisted that somatic cell gene transfer (SCGT) was simply a logical extension of available techniques for treating disease. Those advocating gene transfer research argued, convincingly, that products of genetically modified somatic cells are similar to medications currently available (e.g., enzyme therapies for adenosine deaminase [ADA] deficiency) and that the techniques involved are similar to other widely used medical interventions (e.g., transplantation of tissues). At the time, much ado was made about the fact that the proposed genetic modifications would affect only non-reproductive cells. Out of this debate emerged a moral demarcation line between SCGT and germ-line gene transfer (GLGT); under certain constraints and with appropriate oversight, it would be ethically acceptable to proceed with SCGT research, provided the proposed interventions would not affect the germ cells. The science moved forward on these terms; the ethical debate was, for some time, relatively quiescent.

In the late 1980s and early 1990s, however, with the move to clinical trials involving SCGT, debate about the ethics of gene transfer experiments resurfaced. Many began to question the entrenchment of the moral demarcation line between SCGT and inheritable genetic modification (IGM) and, in particular, to emphasize the potential benefits of research on IGM, especially GLGT.