Beautiful sounds are heard with sensitive ears. A babbling stream, ethereal birdsong, and moving music are always refreshing, but people with severe deafness are completely isolated from the rich world of sound. Deafness is a major public health problem facing the world. I. What is genetic diagnosis of deafness? ”Why do parents with normal hearing give birth to deaf children?” , “Is it true that a combination of deaf people will only produce deaf offspring?” , “Why can’t the child hear anymore after a shot of gentamicin?”, “Why can’t the child hear anymore after a shot of gentamicin?” Many of our deaf friends are often puzzled by the above questions. The dragon gives birth to the dragon, the phoenix gives birth to the phoenix, the son of a mouse will make a hole. In fact, this proverb itself contains the natural principle of genetics. Everything in the world, the reproduction and independent existence of each life from generation to generation, depends on the role of genetic material – genes. It is impossible for two people to exist in the world with identical genetic makeup. The genes of each family are both “common” and “different”, and bad mutations in genes can cause diseases and bad genes can be passed from generation to generation. In China, 55-60% of severe deafness is related to genetic factors, and another 40% is related to environmental factors, such as ototoxic drugs, perinatal infections, neonatal jaundice, ischemic and hypoxic diseases, and noise. The emergence of deafness genetic diagnosis can well explain the above problems. Deafness genetic diagnosis, also called deafness molecular diagnosis or DNA diagnosis, is a technique of molecular biology and molecular genetics to detect whether the molecular structure level and expression level of deafness-related genes are abnormal, so as to make a judgment on the cause of deafness. On the basis of deafness genetic diagnosis, DNA of embryo or fetus is extracted for deafness genetic testing, which can determine whether the fetus is born with deafness. II. Who needs deafness genetic diagnosis and prenatal diagnosis? When should deafness genetic testing be performed? 1.Patients with deafness and their main family members: Genetic diagnosis for patients with deafness can help to clarify the cause of deafness, and genetic testing for family members of patients can help to clarify the carrying status of deafness gene mutation in family members, so that scientific genetic counseling and guidance can be given before marriage and childbirth. Then, after the cause of deaf children in their families is clearly identified through genetic diagnosis, further prenatal diagnosis of the fetus in the mother’s womb and pre-birth guidance can prevent such families from having deaf children again. 3. People to be treated with aminoglycosides: Aminoglycoside antibiotics are widely used in clinical practice because of their low price, rapid clinical effect, and difficulty in developing drug resistance, despite their clear otolaryngotoxicity. The detection of drug-sensitive mitochondrial mutations in the population to be treated with aminoglycosides can help screen out sensitive individuals and avoid the occurrence of post-drug deafness by issuing medication cards and giving medication instructions to patients and their maternal family members. 4. Pregnant women: At least 6% of the normal hearing population in China carry mutations in common deafness genes such as GJB2 and SLC26A4, and if two individuals with normal hearing carry the same mutation at the same time, there is a 25% chance of having a deaf child. The next generation can be prevented. 5. Newborns: Deafness genetic testing in conjunction with hearing screening after birth is important for early detection and treatment of deafness. When should deafness genetic testing be performed? 1. Deafness genetic diagnosis should be performed after deafness is detected; 2. Deafness genetic testing should be performed before marriage for deaf young people, and pre-marital genetic counseling should be performed after the genetic cause is clarified, so that the vertical transmission of deafness after “deaf-deaf” marriage can be avoided through clear guidance of marriage; 3. Genetic testing for deafness in individuals who are to be treated with aminoglycosides can provide proper pre-drug counseling for them and their maternal family members who are also genetically susceptible to ototoxic drugs, thus effectively avoiding the tragedy of deafness; 4. 4. How to perform genetic diagnosis of deafness and prenatal diagnosis? For deafness genetic diagnosis, for those who are to be tested, only peripheral blood or heel blood or epithelium shed from oral mucosa is collected and DNA is extracted by professionals for testing; for pregnant women who need prenatal diagnosis of deafness, amniotic membrane of the fetus is taken under ultrasound guidance around 11-13 weeks of pregnancy, or later, amniotic fluid or umbilical cord blood can be taken and handed over to professionals for DNA extraction for testing. If the fetus is found to be genetically deaf, the family can choose to terminate the pregnancy to avoid the birth of a second deaf child; in this way, parents with the deafness gene mutation can have a healthy hearing child through prenatal diagnosis. In addition, the same tragedy could have been avoided if their relatives who might have carried the deafness gene had come for prenatal diagnosis when they were pregnant with their first child. It is important to get the results of the deafness gene diagnosis interpreted and guided by a qualified doctor. ”With the continuous progress of science and technology, more and more deafness genes will come to the surface and high throughput testing technologies will be introduced, which will help more and more deaf people to clarify the cause of deafness and provide a broader space for prenatal deafness genetic diagnosis. This will provide a broader scope for prenatal genetic diagnosis of deafness. With the correct understanding of the pathogenesis of deafness, the use of deafness gene diagnosis and prenatal diagnosis technology can clarify the cause of deafness and effectively reduce the number of deaf people born.