Putting genetics in perspective

Requires better understanding and more rational debate

How will genetics affect society? Is it a science without clear application, or will it bring important health gains? Should we be hugely excited about its potential or worry about the ethical dilemmas it poses? Unquestionably views are polarised, 1 2 as this special issue of the BMJ reflects.

The impact on health and health care of the sequencing of the human genome has been well rehearsed.3 Our understanding and categorisation of disease will be enhanced. Drug therapy may become safer and more effective as treatments are tailored to take account of individual responses to drugs. Genetic tests will increasingly be used to predict the risk of disease and initiate preventive action. Drug development will become faster and more efficient.

Yet hidden among these simple statements lurks great complexity. Extrapolating from single gene disorders such as Huntington's disease to predict how genetics might affect future health care will mislead. In this disorder the detection of an abnormal variant or mutation in the relevant gene is highly predictive of disease. But in other single gene disorders, such as hereditary haemochromatosis, predicting clinical outcome is harder for it is modified by both other genes and environmental factors.

Genetic factors are even more subtle in the way they contribute to most common diseases.4 These develop because of interactions between many genes with low penetrance and environmental factors, and individual genetic variants may have little predictive power. These complexities are often not appreciated and the media tends to suggest that genetic factors are highly deterministic.5

Dissecting the genetic and environmental influences on common diseases presents a huge and long-term challenge. Success will depend on cooperation between governments, research councils, universities, and the commercial sector. It requires vast collections of community based population data and bioinformatic, biostatistic, epidemiological, and sequencing data. The Medical Research Council and the Wellcome Trust initiative to establish a database of half a million individuals in the United Kingdom population is one example. It will analyse variations in individual genomes and exposure to environmental factors such as smoking and correlate these with the development of disease.6

All countries must consider introducing statutory frameworks to regulate genetic technologies. These frameworks should be robust enough to protect patient and public interests but balanced enough to allow new developments, including predictive tests, gene therapies, and reproductive technologies. Contentious issues raised by patents, confidentiality of data, insurance and employment, and private sector provision of genetic services raise concerns that must be addressed rationally and openly.7

What of the impact of advances in genetics on health services? In the UK the NHS will certainly need to adapt by forging closer partnerships between medical geneticists and other specialties and educating staff. A national approach to service development is needed, and last week's news that the government will publish its first green paper on genetics is welcome (p 1018).8 Awareness that demand for services may exceed resources and capacity is behind the recent establishment by the Department of Health of the Genetics Commissioning Advisory Group. The group will develop mechanisms for evaluating and setting priorities for genetic technologies within the NHS.

As genetic testing becomes more widespread, molecular genetic and cytogenetic laboratories could provide a service similar to chemical pathology, accessed directly by clinicians. All specialists will have to become familiar with the genetic factors underlying the diseases they see. General practitioners will need to acquire specific skills, including assessing genetic risk (p 1027).9 Geneticists will continue to have a unique role because of their expertise in counselling and long term management of patients with genetic disorders. All must recognise that individuals may not want to undergo predictive testing or change their behaviour in accordance with risk predictions (p 1056).10

In time, health promotion programmes may take into account individual susceptibility to disease and provide more individualised approaches to behavioural change. Public health professionals will need to explore how genetic factors influence health and disease in populations and target interventions, such as screening programmes, at genetically defined subpopulations to improve their efficiency.11

Public health genetics, the application of advances in genetic science to improve health and prevent disease, is beginning to have an influence in the UK and the United States.10 Policy development must inevitably take into account issues wider than health and health services because the consequences of genetics for society reach beyond the boundaries of health services. Politicians and policy makers must therefore learn more about this complex science so that they can provide responses based on fact and evidence rather than prejudice and misunderstanding.

Public interest in genetic information and genetic tests is likely to grow. Health professionals need to understand the scope and limitations of genetic technologies and the controversial issues they raise. They, more than any other group, have a responsibility to promote public understanding and help their patients distinguish between hype and reality.