Congenital deafness is the most common type of sensory system disorder, with a prevalence of up to 1% in newborns. With the development of newborn hearing screening in China, early detection, early diagnosis and early intervention of deafness have received more and more attention and recognition. Genetic factors account for 50% of congenital deafness, and in the past 10 years, scientists have identified genes that cause deafness through research and have studied In the last decade, scientists have identified the genes that cause deafness and have developed genetic tests for deafness, which have moved from laboratory studies to clinical applications. Deafness genetic diagnosis enables to understand the pathological mechanism of deafness, to predict the prognosis of the patient’s condition and the probability of deafness in the next generation, and to intervene early depending on the situation. For example, patients carrying mitochondrial DNA mutations avoid the use of aminoglycosides in order to prevent the development of drug deafness. Therefore, diagnosis at the genetic level of deafness will receive increasing attention. How many types of hereditary deafness are there? In general, deafness can be classified according to the mode of inheritance as autosomal dominant, autosomal recessive, X and Y chromosomal companion, and mitochondrial maternal. Autosomal recessive inheritance has the highest percentage of deafness, and because it requires each parent to carry a disease-causing allele, it usually presents as an epidemic case; autosomal dominant inheritance can often have many deafness patients in a large family line, and deafness roams the family line like a ghost. Some children with mitochondrial mutations can develop aminoglycoside ototoxicity, which can sometimes cause deafness with a single injection, even with normal doses of drugs! The genetic diagnosis of deafness is simple and can be done by taking only 5 ml of blood or, in the case of infants, finger blood. It is usually necessary to take a blood sample from both parents, so that the doctor can make a clear diagnosis. GJB2 gene: Mutations in the GJB2 gene can cause congenital profound deafness, which is an autosomal recessive mode of inheritance. In some European and American countries, this gene mutation can account for 50% of congenital deafness, and in China, although the proportion is not as high as in foreign countries, it also accounts for 14%-16%, so it has received widespread attention. Currently, there is no effective treatment for deafness caused by this gene mutation, but cochlear implantation can help these children to gain hearing, and the hearing recovery is usually good after the surgery. SLC26A4 gene (also known as PDS gene): This gene mutation can cause two clinical manifestations, one is Pendred syndrome, which is characterized by goiter and deafness, and the other is deafness only, with an enlarged vestibular aqueduct detected on CT. Some of these children are born with normal hearing and usually develop hearing loss after a minor trauma (especially head trauma), which can be partially recovered after a period of time, but after several episodes of gradual hearing loss, a cochlear implant is eventually needed to help restore hearing in these children. The SLC26A4 gene diagnosis for these children allows early detection, reminds parents to avoid trauma and delays the hearing loss, which can buy precious time for the child’s language development. It should be noted that scientists in China have found through research that the rate of SLC26A4 gene mutations in children with congenital deafness in some regions is much higher than that reported abroad, so this gene may play a more important role in the pathogenesis of deaf children in China. Mitochondrial gene mutations: Mitochondrial gene mutations have been mentioned earlier in relation to the ototoxicity of aminoglycosides, and therefore have received attention. Clinically used aminoglycosides include gentamicin, streptomycin, minomycin, kanamycin, butamycin, neomycin and a large class of antibiotics, which are widely used in clinical practice due to their good antibacterial effect. are often associated with mitochondrial gene mutations. There are also some patients who do not show ototoxicity from aminoglycosides and can develop deafness like other gene mutations, even without medication. After mitochondrial gene diagnosis, if a child is found to carry a mitochondrial gene mutation, parents or patients can be informed that they should avoid aminoglycoside drugs in the future to prevent the development of deafness. Scientists predict that there are more than two hundred causative genes that cause deafness, and there are many deafnesses that are still unknown to people. At present, deafness gene diagnosis is still in the development stage, and the method of gene mutation detection will be improved continuously, and as people’s living standard improves and their demand for quality of life becomes higher, the deafness gene diagnosis method will be improved day by day to benefit more deafness patients.