Polymerase chain reaction (PCR) is a molecular biology technique for amplifying specific DNA fragments, which can be regarded as a special DNA replication in vitro. The biggest feature of PCR is that it can greatly increase a small amount of DNA. Therefore, whether it is paleontological fossils, the remains of historical figures, or the hair, skin or blood left by a murderer in a murder case decades ago, as long as a little DNA can be isolated, it can be amplified and compared by PCR, which is also the power of "trace evidence".

This idea was first put forward by Mullis in the United States in 1983, and the simple DNA amplification method was invented by Mullis in 1985, which means the real birth of PCR technology. Up to now, 20 13, PCR has developed to the third generation technology. From 65438 to 0976, Taiwan Province scientist Qian Jiayun discovered polymerase, which made a fundamental contribution to the development of PCR technology.

Clinical application:

1, infectious diseases.

The most valuable application field of PCR in medical laboratory science is the diagnosis of infectious diseases. Theoretically, as long as there is a pathogen in the sample, PCR can detect it. Detection of pathogens by PCR solves the "window period" problem of immunological detection, and can judge whether the disease is in recessive or subclinical state.

2. Tumors.

The increase and mutation of oncogene expression can occur in the early and benign stages of many tumors. PCR technology can not only effectively detect gene mutation, but also accurately detect the expression of oncogenes, which can be used for early diagnosis, classification, staging and prognosis judgment of tumors.

3. Genetic diseases.

The first clinical application of PCR technology began with the detection of gene mutations in sickle cell and β -thalassemia. Mutation and deletion of genes will cause imbalance in the expression of various globin genes. FQ PCR is an effective method to diagnose thalassemia.