The Ethical Principles of Gene Therapy

 The Ethical Principles of Gene Therapy

1 - Therapy vs. enhancement. There is a consensus that gene therapy should be therapy, i.e. the correction of bona fide disease conditions, rather than enhancement, which would mean "improving the human species" (whatever that means...) and therefore would entail the introduction in human subjects of novel characteristics going beyond the usual, medical, understanding of health (i.e. health as absence of serious disease).

2 - Somatic vs. germ line gene therapy. All current research on humans deals with somatic gene therapy. In these projects somatic cells such as bone-marrow, liver, lung or vascular epithelium etc. are genetically modified. Since the germ line is not affected, all effects of therapy end with the life of the patient, at the very latest. In fact, most somatic therapies will probably require repeated applications, much like ordinary pharmacological treatments.

3 - Germ line therapy is "open-ended" therapy. Its effects extend indefinitely into the future. This basically fits the objective of germ line therapy (assuming that it becomes possible one day), namely to correct a genetic defect once and for all. But precisely there lies also an ethical problem: an experiment in germ line therapy would be tantamount to a clinical experiment on unconsenting subjects, which are the affected members of future generations. This raises a number of very complex questions and is, in my view, an important but not necessarily overriding argument. A recent symposium on germ line engineering has concluded with a cautious "yes-maybe" for germ line gene therapy (see references).

4 - Germ line therapy may involve invasive experimentation on human embryos. Although there are other potential targets for germ-line interventions, much of the discussion revolves around the genetic modification of early embryos, where the germ line has not yet segregated from the precursors of the various somatic cell types. As a result, the ethical assessment of germ line gene therapy will hinge in part on the ethical standing accorded to the early human embryo and the moral (dis)approval of early embryo experimentation. Those who believe the early embryo to be the bearer of considerable intrinsic moral worth or even that it is "like" a human person in a morally-relevant sense will conclude that embryo experimentation is to be rejected and germ-line therapy as well. Others think that it is only later in development that humans acquire those features that make them ethically and legally protected human subjects to the fullest degree. For them, the use of early embryos is not objectionable and germ line therapy cannot be ruled out on these grounds alone. As might be expected in view of the moral pluralism of modern societies, the policies of European countries differ in this respect: some permit some invasive research on human embryos (UK, Spain, Denmark), others ban it (Germany, Norway), others are still undecided. More generally, embryo-centred controversies are expected to increase as the field of embryonic stem-cell research becomes ever more promising. It is expected that this field will catch much of the public attention that was devoted to gene therapy in the nineties.