There are many causes of deafness, about 60% of deafness is related to genetic factors, and genetic mutations associated with deafness are not uncommon in the normal population, which is one of the important reasons why the incidence of deafness remains high. Due to the complex structure of the cochlea, the hearing performance of deafness is difficult to differentiate and conventional tests cannot give a satisfactory explanation from etiology. In contrast, deafness-causing genetic mutations can be found in 70-80% of patients with hereditary deafness, making deafness genetic testing one of the most effective methods available for etiologic analysis, while providing guidance for treatment, prevention and prognosis. In fact, deafness genetic testing is not required only for deaf patients or families who have already had a deaf child to have another child. Since the carrier rate of the deafness gene in the normal population is about 4-6%, even couples with normal hearing are at risk of having a deaf child because they carry the deafness gene mutation. The reason for this is that even though both couples have normal hearing, there is a 25% chance that their offspring will carry the disease-causing double allele and cause deafness to occur. Families seeking prenatal diagnosis of deafness genes are divided into the following situations: 1. 1. Prenatal diagnosis of deafness gene: DNA of the fetus is obtained through chorionic villus, amniotic fluid or umbilical cord blood puncture technique, and relevant genetic tests are performed, i.e., fetal DNA is tested for the gene that causes deafness in the family’s prenatal witnesses, and a prenatal diagnosis report is issued based on the results. 2. If the molecular cause of deafness cannot be clearly identified through genetic testing for the child (the pre-documented person) whose deafness has been detected in the seeking family, prenatal diagnosis cannot be performed for the family at this time. Second, the second type of situation in which prenatal diagnosis of deafness genes is sought: Both spouses have normal hearing and no family history of deafness. However, a mutation of the deafness gene in both spouses is detected during preconception or prenatal examination. If both husband and wife have the same deafness gene mutation, prenatal diagnosis of fetal deafness is recommended after informing them of the risks involved; 2.