Parents of children with deafness often bring their children to the hospital. Most of their questions are: Why can’t our children hear? What causes it? Can it be treated? The doctors’ answers to these questions are often vague, or they simply diagnose neurological deafness and put the child on hearing aids or cochlear implant therapy. There have been tremendous advances in deafness diagnosis due to the use of molecular genetics techniques in deafness diagnosis. Available research indicates that at least 70% of deafness is caused by genetic factors, i.e. hereditary deafness. This means that genetic diagnosis can be performed to clarify the cause of deafness in at least half of the affected children. (a) Non-syndromic deafness has more genetic causes of hereditary deafness is divided into syndromic deafness and non-syndromic deafness. Syndromic deafness has other systemic abnormalities, but they are less common and more common in nonsyndromic deafness, which accounts for about 70% to 80% of the overall genetic deafness. Because non-syndromic deafness tends to be autosomal recessive and is mostly disseminated, i.e., there are no other deaf people in the family other than the patient. This type of deafness can easily lead to an incorrect etiological diagnosis. The deafness may be congenital, may occur after birth, and may be related to the use of medication. The hearing loss may be present at birth, may be gradual, or may be mild and fluctuating. (b) Genetic tests can identify the cause of deafness The common genes that cause deafness can now be routinely examined on an outpatient basis. Routine genetic tests include the GJB2 gene, the mitochondrial gene PDS gene, and others. These genes are all key deafness-causing genes or mutation-causing genes. Genes and congenital deafness are closely related. About 20% of Chinese congenitally deaf patients carry mutations in the GJB2 gene. Mutations in the mitochondrial gene are closely related to drug deafness caused by aminoglycosides such as streptomycin, gentamicin, and kanamycin. mutations in the PDS gene can cause large vestibular aqueduct syndrome, which is clinically manifested as congenital or acquired deafness, and the occurrence or aggravation of deafness is related to trauma and cold. These three genes cause about 80% of the overall genetic deafness. Therefore, testing for these three genes can clarify the cause of most hereditary deafness. (iii) Genetic diagnosis can provide the right remedy for deafness Genetic diagnosis of deafness has brought light to break through the sound barrier. Genetic diagnosis can remove the psychological fear of deafness, guide medication and daily behavior, and allow for confident re-birth through prenatal diagnosis. If the child’s genetic diagnosis indicates that the congenital deafness is due to a mutation in the GJB2 gene, then the child’s ear nerve conduction pathway and auditory speech center should be normal and a cochlear implant can be performed with good results. If the gene test is positive, the mother of the child should always avoid aminoglycoside antibiotics such as gentamicin in her family to prevent drug-related deafness from occurring. Performing a prenatal genetic diagnosis is especially significant for couples at risk of having a child with deafness. When they have given birth to a deaf child and are eager to know about the second child, genetic diagnosis coupled with prenatal diagnosis can clarify the genetic status of deafness in the fetus after 10 weeks of pregnancy and allow early interventions to prevent the birth of a deaf child. (4) Genetic diagnosis of deafness can be done remotely Compared with audiological examination and imaging examination such as X-ray, genetic diagnosis of deafness has stronger target and specificity, and it is convenient to take materials and has wide application. When the genetic diagnosis of deafness is clear, the patient basically receives the final diagnosis. When hereditary deafness is suspected and the patient is unable to visit a unit with testing conditions due to geographic and economic reasons, the patient can also be examined without the site and only a small amount of blood is collected or a small amount of skin, hair, or cheek mucosa is taken and sent to the testing unit, and the results are known in 3-7 days. The test results can provide ENT doctors with accurate information different from conventional deafness diagnosis, so that they can target scientific counseling and treatment to patients, thus achieving the goal of reducing the incidence of hereditary deafness.