Hereditary deafness can also be classified according to the mode of inheritance as autosomal dominant, autosomal recessive, X-chromosome chain dominant, X-chromosome chain recessive, Y-chromosome chain and mitochondrial gene disorders, of which autosomal recessive is the most dominant mode of inheritance, accounting for about 80%. Usually, the mode of inheritance can be inferred from the information provided by the patient and his/her family: 1. Autosomal dominant inheritance: ① one of the two parents of the patient has the disease; ② l/2 of the patient’s siblings have the disease, equal opportunity for men and women; ③ 1/2 of the patient’s children have the disease, each birth has 1/2 of the possibility of the affected child; ④ when both parents do not have the disease, the children generally do not have the disease, only the occasional new mutation will develop. 2. Autosomal recessive inheritance: The disease develops only in the pure state of the disease-causing gene, which is the most common form of inheritance of hereditary deafness. This is why we often see babies born from parents who are not deaf. (a) The genealogical characteristics of X-linked recessive inheritance: (i) more male patients than female patients; (ii) when both parents are disease-free, the son can develop the disease, and the causative gene comes from the carrier mother; (iii) the brothers and uncles of the patient have a l/2 risk of developing the disease. (b) The genealogical characteristics of X-linked dominant inheritance are: (i) more females than males are affected, and females are often less affected than males; (ii) one of the two parents must be affected; (iii) all daughters of male patients are affected and sons are normal, and 1/2 of the children of female patients are affected; (iv) continuous transmission. (c) Y-linked inheritance, father to son, one son to grandson, female does not develop the disease. For example, the A1555G and C1494T mutations in the mitochondrial MT-RNR1 gene are the main form of mutation in mitochondrial maternal inherited deafness, and female carriers will pass this mutation to so children, of which daughters will continue to pass Carriers are sensitive to ototoxic drugs, mainly aminoglycosides (gentamicin, streptomycin, etc.); carriers are at risk of deafness once treated with these drugs, and in severe cases deafness is caused by one injection. Therefore, the diagnosis of one case of deafness caused by mitochondrial MT-RNR1 gene mutation through deafness genetic diagnosis can provide an early warning to the whole family, thus avoiding the recurrence of drug-related deafness in the whole family and future generations.