HapMap, pharmacogenomics, and the goal of personalized prescribing.

Most of the gene variants that have been identified in the last 50 years have affected individual drug responses through effects on pharmacokinetics. Gene variants that affect a drug's pharmacodynamics, such as polymorphisms in receptors or signalling molecules, have been more difficult to identify. This often requires a more systematic and genome-wide approach, prompting the emergence of the new discipline of pharmacogenomics. The provision of the human genomic sequence and now data from the HapMap project look set to bring 'personalized prescription' a step closer.