Abstract
1. Information and technologies derived from genomic research are beginning to revolutionize the study of disease. It is now being predicted that the human genome sequencing project will be more than 90% complete by the end of this decade and that most of the major genes involved in common diseases will have been identified by that time. Correlations between genetic mutations, disease susceptibility, and adverse reactions to drugs are already being established and it seems inevitable that this will lead to the development of novel therapies accurately targeted at subsets of patients most likely to show a favourable response. 2. Targeted therapies present a significant challenge to the pharmaceutical industry because the potential market for such drugs is likely to be smaller than for current 'phenotypic' treatments. However, application of molecular genetic technologies may allow parallel reductions in development costs since it should be more straightforward to demonstrate efficacy and safety in accurately selected patient groups, reducing the requirement for large clinical trials. 3. Gene-based diagnostics have the potential to radically improve medical practice, and progress in genetic testing technology has been impressive. Yet there is growing concern that commercial and other pressures may result in genetic testing being made widely available before the biological consequences of mutations in disease susceptibility genes are fully understood and before the legal, ethical and psychological consequences of testing have been fully debated.