Pharmacogenetics

Pharmacogenetics is the variability of drug response due to inherited chara cteristics in individuals. Drug metabolizing enzymes have been studied for decades, first as chemical reactions and, more recently, as specific polymo rphisms of known molecules. With the availability of whole-genome single-nu cleotide polymorphism (SNP) maps, it will soon be possible to create an SNP profile for patients who experience adverse events (AEs) or who respond cl inically to the medicine (efficacy). Proof-of-principle experiments have de monstrated that high density SNP maps in chromosomal regions of genetic lin kage facilitate the identification of susceptibility disease genes. Whole-g enome SNP mapping analyses aimed at determining linkage disequilibrium (LD) profiles along an ordered human genome backbone are in progress. SNP 'fing erprints' or SNP PRINTssm will be used to identify patients at greater risk of an AE, or those patients with a greater chance of responding to a medic ine. As LID maps for various ethnic populations are constructed, the number of SNPs necessary to measure for an individual will decrease. Standardized pharmacogenetic maps for drug registration and post-marketing surveillance will result in safer, more effective and more cost-efficient medicines. Th e timing of these pharmacogenetic applications will occur over the next 5 y ears. In contrast, the benefits of pharmacogenomic applications such as the identification of new tractable targets will not be visible as new medicin es for 7-12 years, due to the lengthy drug development and registration pro cesses.