Genetic testing is the technique of testing genes through blood or other bodily fluids. By extracting and analyzing genes to check whether the structure of genes and the genetic information expressed are normal, it can help determine the risk of occurrence or the degree of development of certain diseases, and thus prevent or treat certain diseases. The main means of genetic testing are biochemical testing, chromosomal analysis and DNA analysis. The common uses are: 1. Clinical disease diagnosis: especially for the diagnosis of certain diseases of the fetus, such as Down’s syndrome. Fetal DNA fragments are extracted by drawing maternal peripheral blood, or karyotype analysis by amniocentesis of fetal exfoliated cells. In addition, genetic testing has good sensitivity and speed for the diagnosis of infectious diseases such as tuberculosis. 2. Genetic sequencing and chromosomal analysis of non-diseased patients can roughly determine the risk of certain genetic-related diseases in normal people, so as to prevent them; 3, to guide the precise use of drugs: genetic testing can help guide clinicians to select therapeutic drugs and judge the dosage of drugs, assess whether patients have the risk of serious adverse reactions to certain drugs, so as to prevent them, and can also detect the genotypic resistance of viruses and It can also detect viral genotype resistance and select appropriate drugs.