Polymerase Chain Reaction

Kary Mullis, Cetus, USA, patent 4,683,202 of 1987. Copying DNA a billionfold in a test tube.

Overview

Kary Mullis conceived the polymerase chain reaction in 1983 while driving through the California hills at night. Repeated cycles of heating and cooling double a chosen stretch of DNA each time, and the heat-stable Taq polymerase from hot spring bacteria made the process automatic. Cetus patented it, and in 1991 sold the rights to Hoffmann-La Roche for 300 million dollars. Mullis received only a modest bonus but shared the 1993 Nobel Prize in Chemistry. PCR now underpins genetics, forensics and diagnostic testing.