PCR, short for polymerase chain reaction, is a method used to rapidly make millions to billions of copies of a DNA sample and amplify it (or a part of it) to a large enough quantity to study in detail. Kary Mullis, the inventor of the polymerase chain reaction, noted in an interview before his sudden death in 2019 that PCR "doesn't tell you that you're sick" and that "with PCR if you do it well you can find almost anything in anybody."

---