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Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• What is PCR (polymerase chain reaction)?
• How is PCR (polymerase chain reaction) done?
• What is the purpose of doing a PCR (polymerase chain reaction)?
• How was PCR (polymerase chain reaction) discovered?
• What is RT PCR?
• PCR (Polymerase Chain Reaction) Index

How was PCR (polymerase chain reaction) discovered?

PCR was invented by Kary Mullis. At the time he thought up PCR in 1983, Mullis was working in Emeryville, California for Cetus, one of the first biotechnology companies. There, he was charged with making short chains of DNA for other scientists. Mullis has written that he conceived of PCR while cruising along the Pacific Coast Highway 128 one night on his motorcycle. He was playing in his mind with a new way of analyzing changes (mutations) in DNA when he realized that he had instead invented a method of amplifying any DNA region. Mullis has said that before his motorcycle trip was over, he was already savoring the prospects of a Nobel Prize. He shared the Nobel Prize in chemistry with Michael Smith in 1993.

As Mullis has written in the Scientific American: "Beginning with a single molecule of the genetic material DNA, the PCR can generate 100 billion similar molecules in an afternoon. The reaction is easy to execute. It requires no more than a test tube, a few simple reagents, and a source of heat."

What is RT PCR?

RT-PCR (Reverse transcriptase-polymerase chain reaction) is a highly sensitive technique for the detection and quantitation of mRNA (messenger RNA). The technique consists of two parts:

• The synthesis of cDNA (complementary DNA) from RNA by reverse transcription (RT) and
  
  
• The amplification of a specific cDNA by the polymerase chain reaction (PCR).

RT-PCR has been used to measure viral load with HIV and may also be used with other RNA viruses such as measles and mumps.

Previous contributing author and editor:
Medical Author: Frederick Hecht, MD, FAAP, FACMG
Medical Editor: Leslie J. Schoenfield, M.D., Ph.D.