ABSTRACT
Pharmacogenetic studies have established the importance of polymorphic drug-metabolizing enzymes, receptors and transporters in the differential response of patients to drugs. Among these target genes, cytochrome P450 (CYP) has become the most important subject of exten sive studies concerning individual variation of drug metabolism and disposition. The associa tion between decreased drug clearance and activity of several kinds of CYP enzymes, the inher ited nature of the deficiency, and their frequencies and clinical importance were evaluated extensively. During the past 20 years, the genetic polymorphisms of these genes have been studied at the protein and gene level. Analysis of allele frequencies in different populations revealed individual and interethnic differences that contribute to the molecular mechanisms responsible for interindividual variations in drug metabolisms and responses. In recent years, we also demonstrated that genetic differences among racial and ethnic groups usually reflect differences in the distribution of polymorphic traits, which occur at different frequencies in different populations.
