Review ArticleHuman Germline Genetic Modification: Scientific and Bioethical Perspectives
Introduction
Once the preserve of science fiction, the idea of genetically modifying humans at the germline level is becoming increasingly plausible as a consequence of recent scientific and technological developments. In this paper we argue that strong ethical grounds exist to pursue the goal of human germline genetic modification (HGGM). In terms of developing the technologies that will be required for effective and safe HGGM, no serious ethical prohibitions pertain. Indeed, the requisite technologies are already under intensive development as part of a) scientific research into fundamental biological process (such as the development of transgenic mice to study developmental processes) and b) applied research for biotechnological and bioscientific purposes (such as the development of vectors for somatic gene therapy). Thus, whether or not society decides to actively pursue HGGM as a specific goal, the tools for achieving it will be constructed anyway. The scientific and technical basis for HGGM is considered in some depth in this paper.
Various objections have been raised against the potential use of HGGM. These objections range from concerns over safety to fears for the welfare or identity of genetically modified individuals, to fears for the future state—or the very existence—of the human species. We examine such objections and conclude that none of them, taken either individually or in their totality, provide good reasons to prohibit HGGM.
The human genome is not perfect, and there exist no good biological reasons to presume that the genome cannot, at least in principle, be improved. By altering the human genome, HGGM offers major future benefits to the population including protection from major diseases (such as cancer and AIDS) that presently afflict the human species. Ultimately, HGGM offers the possibility of genetic enhancement, such that normal or species-typical functioning is enhanced by improved human capacities and abilities. In the future, HGGM could result in the birth of persons who are altogether better: for example, such genetically modified persons might live longer and have improved cognitive and physical abilities.
The common reaction to the notion of human genetic modification is one of rejection: by contrast, we seek to provide good reasons for believing not only that HGGM is ethically acceptable, but that it is ethically imperative to positively support its development.
Section snippets
Dealing with Simplistic Objections to Genetic Modification
HGGM requires two fundamental processes: 1) the deliberate alteration of genetic sequences and 2) the use of human embryos and consequent loss of some of these embryos. Objections are frequently raised against these processes. As such, the arguments commonly deployed amount to rather simplistic assaults on HGGM.
Background
Germline genetic modification of the mammalian genome is not new: reports of successful animal GM date back to the 1980s. Following the first reports of stable heritable alterations, genetically modified animals (transgenic animals) rapidly became an invaluable tool for biomedical research. Although the mouse has been the most frequently modified animal, many other mammalian types ranging from rodents to large agricultural animals and primates have also been successfully modified. Thus, the
Ethical Considerations in HGGM
The methods described above seem to offer genuine possibilities for HGGM and the potential for thereby improving human welfare is, at least in theory, vast. Actually applying these techniques to achieve HGGM, however, remains largely a matter of theory rather than practice. This is at least partly due to concerns over the ethical issues associated with HGGM and the consequent restrictive regulatory environments in many jurisdictions that do not permit inheritable genetic modification for humans
Human Germline Genetic Enhancements (HGGE)
A prominent theme in relation to HGGM is the prospect of genetic enhancement: not just ‘curing’ genetic disease but improving on the human genome to confer, for example, longer lifespans or resistance to disease.
Objections to enhancement per se, simply because it aims to improve on nature or on what is considered ‘normal’, tend to lack logical force (as discussed in, for example, references 123, 133, 134). Our general attitude towards medical science demonstrates that we have little moral
Conclusions
Putting aside safety concerns and efficiency limitations, animal GM technology, in its present state of development, could in principle be used to modify the human germline. Moreover, GM technology is developing apace: in particular, gene targeting—a crucial component of any plausible HGGM system—is undergoing something of a revolution in the form of designer genetic recombination tools. Additionally, recent advances in other scientific areas, for example the fields of human genome sequencing
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