[Polymerase chain reaction in clinical diagnosis]

The polymerase chain reaction (PCR) is a novel method that amplifies selective sequences of DNA or RNA molecules with unparalleled efficiency. The specificity of PCR amplification is based on two oligonucleotide primers which flank the DNA fragment to be multiplied and hybridize to opposite strands. Repeated cycles of thermal denaturation, primer annealing, and enzymatic extension by the heatstable Taq DNA polymerase result in exponential augmentation of the target DNA. PCR is simple, rapid, and highly sensitive. The nucleic acid content of a single cell is sufficient to detect a particular sequence. This method has an enormous impact on the detection of genetic mutations, sequence polymorphisms and infective agents. This review depicts the mechanism of PCR and explores its applications in clinical diagnostics.