Editor of this issue:

Gail Hendler, Ehrman Medical Library, New York University Medical School, 550 First Avenue, New York, NY 10016, S-10, Phone: 212-263-8925, Fax: 212-263-8196, E-mail: hendler@library.med.nyu.edu.

Pharmacogenetics or pharmacogenomics -- what do these terms really mean and why are they important to health information professionals? People differ in their genetic makeup and consequently in their reactions to drugs. This is the premise of pharmacogenetics, which is the field of genetically determined variability in how drugs are metabolized. The broader term pharmacogenomics refers to drug discovery based on knowledge of genes. The boundaries between these two terms are not clear and they are often used interchangeably.

Pharmacogenomics combines traditional pharmaceutical sciences such as biochemistry with annotated knowledge of genes, proteins, and single nucleotide polymorphisms (SNPs). SNPs will be covered in a future Brave New World column. Identification and mapping of genetic variations are fundamental to pharmacogenomics. Genes provide the manufacturing instructions for all of the proteins. Some proteins actually "turn on" certain medicines, by switching them from an inactive form to an active one. For example, the painkiller codeine is a medicine that is "switched on" in this way by proteins. Reactions to drugs may include lack of effect, reduced effect, normal effect, increased effect or adverse effects. Fagerlund and Bratten explain the science behind pharmacogenomics in more detail.

With the growing application of pharmacogenomics, the one-drug-fits-all approach may be replaced by one in which variants of drugs are specially tailored to subgroups of populations. Sherrid explores why drug companies often have little motivation to segment the market for blockbuster drugs and how biotech firms use pharmacogenomics to develop safety and efficacy tests to determine who should and should not be treated with a particular drug. Clinical and epidemiological studies are needed to fulfill the promise of gene-targeted drug interventions. Khoury and Morris outline three areas of inquiry:

1. how drug response varies among individuals with different genotypes (genetic makeup),
2. what the prevalence of relevant genotypes is in the population and in relevant subpopulations, and
3. whether and to what degree other environmental factors (such as other drugs and diet) interact with genetic factors to influence drug response.