PCR and its variations

The polymerase chain reaction (PCR) is an in vitro technique used to replicate, or amplify, a specific region of DNA billions-fold in just a few hours (Saiki et al., 1985, 1988; Mullis and Faloona, 1987). The amplification is primer directed-oligonucleotide primers anneal to and flank the DNA region to be amplified. PCR is used in diagnostic and research laboratories to generate sufficient quantities of DNA to be adequately tested, analyzed, or manipulated. Because of the exquisite sensitivity it offers, PCR has rapidly become a standard method in diagnostic microbiology. More recently, reagent kits and various instrument platforms have added speed, flexibility, and simplicity (Tang et al., 1997; Fredricks and Relman, 1999; Tang and Persing, 1999). How significant is the contribution of PCR to the field of biomedicine? This question is perhaps best answered by the results of a PubMed search using the key word "PCR" (214,352 hits) or a search using the key words PCR and diagnosis (74,447 hits).