How does PCR help scientists test DNA for genetic mutations?

The polymerase chain reaction (PCR) is a vital tool in genetic testing because it allows scientists to quickly and accurately produce billions of copies of a specific DNA segment from a very small initial sample.1

By generating these large quantities of a target gene, PCR provides researchers with enough material to analyze and identify specific mutations associated with inherited disorders or those present in tumors. The process works through repeated cycles of:1

• Denaturation: Heating the sample to separate the double-stranded DNA into two single strands.1
• Annealing: Cooling the mixture to allow short primers to bind to the specific complementary sequences of the target region.1
• Elongation: Using a heat-stable enzyme called Taq polymerase to synthesize new DNA strands.1

Because PCR can amplify even a single molecule of DNA, it enables precise diagnostic testing that would otherwise be impossible due to the scarcity of genetic material in a typical clinical sample.1