Drugs are administered to patients with the intention of achieving an expected therapeutic response. Yet drug therapy remains a medical art because of the wide variation in individual responses to standard drug doses. Pharmacogenetics emerged as a field aimed at identifying heritable factors that are predictive of individual variations in drug efficacy and toxicity from the dedicated work of a small group of investigators who in the 1950s began to enrich the discipline of pharmacology by integrating it with human genetics. Pharmacogenetics provides the experimental framework to understand variation in human reactions to drugs and other exogenous substances as a function of inborn human genetic variability. Recently, pharmacogenetics has experienced a period of rapid growth and redefinition. The human genome initiative has provided a wealth of primary genetic information and functional genomic data to fuel the understanding of genetic polymorphism and its functional consequences on a genomic scale. Today, the field of pharmacogenetics is a well-integrated, worldwide network engaging a vast community of academic, institutional, and industrial scientists. The second edition of this highly regarded book provides a systematic and comprehensive account of the foundations, fundamentals, and futures of the field of pharmacogenetics and serves as introduction to all facets of pharmacogenetics for physicians, pharmacists, epidemiologists and other professionals in the life sciences. Dr. Wendell Weber has completely revised and updated each chapter in this new edition to reflect the enormous changes in this field.