The gene: the polymerase chain reaction and its clinical application

Chromosomal DNA transfers and stores information regarding the structure and function of the cell. Genetic information, encoded within sequences of nucleotides that compose DNA, is grouped into functional units called genes. Genetic diseases are caused by changes in the chromosomal DNA, leading to a change in the quantity or function of the protein gene product. In the past, genetic diagnosis was limited by the availability of sufficient quantity and quality of DNA and the absence of an efficient amplification procedure. The polymerase chain reaction (PCR), an inexpensive, rapid, and accurate means of amplifying DNA, is already making a major contribution to the diagnostic sciences. PCR techniques have been widely used in diverse applications, including molecular analysis of microbial pathogens, inheritable diseases and syndromes, and neoplasms. The purpose of this article is to 1) Review gene structure and function, 2) review principles of PCR technology and its applications in molecular biology, and 3) discuss an experimental clinical application of PCR to identify novel infectious agents responsible for odontogenic infections.