Introduction

The concept of deliberate, targeted genetic intervention into the human genome has been under discussion since the early 1960s, and the attendant ethical problems have been well-rehearsed in the professional and public arenas. Somatic genetic interventions in humans have been shown to be possible and to effect substantial amelioration in at least a few conditions: the first such “cure” by somatic cell gene transfer (SCGT) was announced in 1990. Although progress in the implementation of SCGT has been slower than hoped, the announcement in 2000 of significant improvement in the condition of children with X-linked severe combined immunodeficiency (SCID) treated by SCGT suggested that somatic genetic intervention may yet become part of the everyday medical repertoire.

The situation is rather different for inheritable genetic modification (IGM), even though IGM may actually face fewer technical difficulties in terms of gene delivery and expression than SCGT. Extensive experience of germ-line modification has been gained from the production of transgenic animals, but as far as is known there have been no attempts to use transgenic technology to modify the human genome, although therapeutic modification of the human mitochondrial genome has been successful.

The abstention is primarily for ethical reasons. Since the 1970s, a professional semi-consensus on the ethics of human genetic interventions has developed. This views somatic, therapeutic (as opposed to enhancing) interventions as ethically acceptable, arguing that they involve no more than the introduction of exogenous material (genes) into an individual's body, and as such are no more ethically problematic than any other expensive, experimental therapy.