Ruth Chadwick charts the ethical course of revolutionary genetics

The challenges for bioethics - the exploration of the ethical, social and legal issues raised by advances in medicine and the life sciences - are twofold.

First is the rapid development not only in technology but also in the opportunities and potential for use of that technology. Second is what is sometimes called the "second phase" of bioethics as it enters a period of critical self-reflection on its methodologies.

Bioethics is multidisciplinary, incorporating philosophy, law and sociology. But the way in which these disciplines can and should work together is the subject of debate, particularly the interplay of philosophical principles and empirical data, and the possibility of "complementarity" of philosophy and social science.

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It is widely accepted that in this branch of applied ethics it is not simply a question of "applying" a ready-made theory to the issues. Medical and technological advances can lead us to rethink our theories and categories.

This is perhaps most obvious in genetics. Alongside progress in mapping the human genome has come considerable discussion about genetic screening. A good example here is the mapping of the breast cancer disposition gene, BRCA1. An individual who carries the predisposition gene has a greater risk of developing cancer, but this outcome is not inevitable. But absence of the predisposition gene does not guarantee freedom from the disease: it is estimated that about 2 per cent of all breast cancers are due to BRCA1.

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The issues for bioethics fall into four categories. The first concerns the contribution of bioethics to discussion of options for action. In what circumstances should predictive testing be offered? What are the implications for insurance and employment prospects of a positive predictive result? How should patients with a positive result be managed, in terms of preventive treatment, such as prophylactic surgery?

The second category concerns the implications of discoveries such as BRCA1 on theory in bioethics itself. In bioethics' short history, a consistent theme has been the desirability of patient access to information - as found, for example, in the doctrine of informed consent. The advent of predictive testing, however, has led to arguments for a right not to know, because it is increasingly recognised that information is not necessarily empowering - there are circumstances in which it can be a burden rather than a help. Also, the fact that knowledge about one's genetic status has implications for genetic relatives has led to reconsideration of the centrality of the individual in ethical theory.

The third category of questions concerns social and political issues, such as the arguments concerning the potential for genetic discrimination and "geneticisation" of social problems so that environmental explanations of phenomena are played down.

The fourth category includes philosophical and conceptual questions about the potential impact of genetics on our understanding of human beings, in terms of, for example, genetic determinism and reductionism; and our understanding of health and illness. While most people think wide genetic screening should be introduced only for diseases which can be classified as serious, the meanings of both "serious" and "disease" are still contested.

A principle that has traditionally drawn support is that screening programmes should only be done where therapy is available. This has recently been modified to include scope for action such as changing the lifestyle.

Advances in genetics are frequently presented in terms of the possible therapeutic benefits in the long term. Here too bioethics is faced with quite rapid change.

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Much of the early theoretical discussion of gene therapy was undertaken before trials. It is thus possible to discuss in principle whether there is a conceptual and moral distinction between gene therapy and genetic enhancement; or between somatic and germ-line therapy. In policy documents around the world, though not among bioethicists, there is some consensus that these distinctions are sustainable.

Philosophical discussion has also been concerned with the implications for personal identity of the manipulation of the germ-line. Here discussion of the ethical issues must be open to the empirical data. For example, it is not irrelevant to the somatic/ germ-line discussion to have empirical data about whether somatic gene therapy may also affect the germ cells.

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Initially gene therapy consisted of adding copies of functioning genes rather than attempting to repair faulty genes (possibly the way of the future). This may affect how we regard the therapy conceptually. It may also be important to have regard to the particular condition in question. Inhaling a gene through a nasal spray, as in cystic fibrosis, may be regarded differently from more invasive approaches.

This point has a general application. While it is of crucial importance to give due consider-ation to key conceptual distinct-ions such as therapy/enhancement and health/disease, the phenomena of particular conditions can make a difference, such that the issues in testing and offering gene therapy (should it be possible) for breast cancer may be very different from, for example, the issues involved in testing and treating cystic fibrosis or thalas-semia. This is where the complementarity of philosophy and empirical data becomes vitally important.

Social context is also relevant. The facts relating to the preval-ence of the carrier state for thalas-semia in Cyprus, for example, are of central significance in an assessment of the philosophical and ethical questions.

Issues are raised starkly in looking at the genetic basis of mental disorder and behavioural genetics. For example, if it were possible to screen for a genetic predisposition to depression. This might facilitate more effective therapy for depression, but also it may have an effect on our very concepts of mental, as opposed to physical, disorders. Here again the interplay between concepts and data comes in. Where behavioural genetics is concerned, there may be opposition to what might be seen as the influence of models of genetic determinism and the potential for social control through genetics, but one underlying assumption insufficiently questioned is that other (environmental) forms of control are to be preferred.

While not all advances in genetics are welcome, similarly blanket opposition on the grounds that they are "eugenics" will not do. There is a conceptual question about what counts as "eugenics", but a rigorous analysis of arguments about the specific phenomena of particular conditions is also needed, having regard to all four of the categories of issues outlined above. This is the task for bioethics.

Ruth Chadwick is head of the Centre for Professional Ethics at the University of Central Lancashire.

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