Principles and applications of the polymerase chain reaction

The polymerase chain reaction (PCR), a primer-directed in vitro enzymatic reaction for the production of a specific DNA fragment, has dramatically facilitated molecular biology approaches to fundamental research questions, as well introduced DNA testing into a variety of clinical diagnostic areas. Some of the principles of PCR, several recent advances in PCR technology and selected applications are reviewed. A variety of methods for analyzing allelic sequence diversity in amplified DNA have been developed. Genetic testing of the HLA loci, and other genes encoding cytokines and cytokine receptors, has had a significant impact on disease susceptibility studies and in clinical transplantation.