The ligase chain reaction in DNA-based diagnosis

Clinical specimens containing a suspected pathogen often have too little of the pathogen's DNA to be detected directly. It is generally necessary to first amplify the DNA and then to detect the amplification products. An amplification technique called the ligase chain reaction (LCR) is described, which in conjunction with an automated, nonradioactive readout format allows less than 10 molecules of target DNA to be detected. A prototype HIV assay and two prototype Chlamydia assays have sensitivities and specificities equivalent to PCR.