The functions of genetic testing include predicting the risk of hereditary diseases, diagnosing diseases, and guiding the use of medication, etc. The above purposes can be accurately and effectively achieved through genetic testing, which has great prospects for development in the clinic. 1. Predicting the risk of hereditary diseases: ① for prenatal diagnosis, terminate pregnancy by detecting children with high-risk diseases through gene testing sequences, such as sickle cell anemia, β-thalassemia, etc.; ② for disease prediction, which can provide the tested person with a risk assessment of the occurrence of certain diseases, so as to take therapeutic measures in advance, such as predicting the susceptibility genes for breast cancer. 2. Diagnose diseases: each pathogen has a specific nucleic acid sequence, through genetic testing, if the exogenous genome or gene fragments found in the human body, then it can be confirmed that the pathogen is infected, common infectious agents are viruses, such as HIV virus, new coronavirus, hepatitis B virus infection. 3. Guidance on drug use: there are individual differences in the reactivity to drugs in the population, resulting in the adverse effects of drugs often have individual differences, such as tumor diseases caused by gene mutations, the use of targeted drug therapy before the use of histological confirmation of pathology or genetic testing can be used only after the shortest possible time to obtain the correct drug therapy, so as to achieve the best therapeutic effect. Compared with previous cytological and biochemical tests, genetic testing is less time-consuming, more accurate, more specific, and has an irreplaceable role, especially in hereditary and oncological diseases with strong guiding significance. It is recommended that patients who need to use this test should always do so under the guidance of a medical professional.