The invention of the polymerase chain reaction (PCR) eventually earned Kary B. Mullis half of the 1993 Nobel Prize for Chemistry (1-4). However, for several years, issues of quality control and reproducibility interfered with attempts at commercial or clinical application of PCR. More recently, persistent work and numerous methodological inno- tions and refinements have resulted in the establishment of PCR as a routine, sensitive, and specific detection method in hospital and agricultural labora- ries. This transformation of PCR from an experimental research technique to an established...