Warfarin: a case history in pharmacogenetics.

Both hereditary and environmental factors contribute to inter-individual variability in drug response. The considerable interest in the role of genes has to be balanced with the contribution of external influences. Warfarin provides a useful case study of the need to integrate both genetic and non-genetic information when selecting the right dose for a patient. This article discusses the latest data on genotype and warfarin sensitivity and the efforts to incorporate this information into normograms. Exploring the genetics of warfarin response will lead not only to safer prescribing but elucidate the mechanism of action of warfarin and enable the development of new anticoagulant drugs.