"He can hear the sound!" Ms. Yan (pseudonym) shouted excitedly with tears in her eyes. Ms. Yan's 2-year-old son Niu Niu (pseudonym), who suffers from congenital deafness, is excitedly knocking and tapping at the door, his mouth still babbling. Niuniu suffers from congenital deafness from birth, and it is the most severe type - total deafness! Now he has received the latest genetic therapy for hereditary deafness. After a month of treatment, the cow was finally able to hear its voice. On January 25th, the top medical journal "The Lancet" published the latest results of a research team led by the Eye, Ear, Nose and Throat Hospital affiliated with Fudan University in the form of a long article: they have demonstrated for the first time internationally the safety and effectiveness of gene therapy in clinical treatment of patients with hereditary deafness. This is the world's first clinical trial of gene therapy for hereditary deafness, demonstrating the potential of gene therapy in curing hereditary deafness and ushering in a new era of gene therapy for deafness. The research team introduced that the number of congenital deafness patients like cows and cows worldwide is as high as 26 million. About 30000 deaf children are born every year in our country, of which 60% are related to genetic factors, namely genetic defects, which severely hinder their language, cognitive, and intellectual development. Although over 150 genes for deafness have been identified, there are currently no therapeutic drugs available in clinical practice. With the innovation and development of biopharmaceutical technology, gene therapy is considered one of the most promising strategies for eradicating hereditary deafness. The use of gene therapy for deafness in clinical practice also requires addressing a series of issues such as pathogenesis, treatment strategies, gene carriers, inner ear administration, and production processes. In order to solve the world problem of hereditary deafness without medicine, Professor Shu Yilai from the Eye, Ear, Nose and Throat Hospital affiliated with Fudan University has been deeply involved in the field of gene therapy for deafness for more than ten years, leading the team to explore for many years and actively cooperate with multiple parties. The team ultimately developed a gene therapy drug for deafness targeting mutations in the OTOF gene (expression of ototoxic proteins), and independently innovated to develop precise and minimally invasive ear delivery pathways and equipment. The pathogenic mutation of the OTOF gene can cause autosomal recessive inherited hearing loss, a type of auditory neuropathy. Patients typically exhibit severe, extremely severe, or complete hearing loss and speech impairment. The incidence rate of deafness caused by OTOF gene mutation is as high as 41% among infants with auditory neuropathy in China. The OTOF gene is mainly involved in the release of neurotransmitters from synaptic vesicles of hair cells in the cochlea, allowing the brain to sense sound. The lack of expression of ototoxic proteins in inner hair cells can lead to the inability of sound stimulation signals to be transmitted to the auditory nerve pathway, resulting in deafness. It is understood that adeno-associated virus (AAV) is currently the most commonly used gene therapy delivery vector, but the OTOF gene exceeds the loading capacity of a single AAV. In order to overcome the problem of delivering large genes to the inner ear, the research team has made unremitting efforts to use the dual carrier delivery system of AAV, which uses two AAV vectors to carry the coding sequence of the OTOF gene. In an OTOF deaf animal model, the team expressed human OTOF protein with normal function, significantly improving hearing. For example, if one car cannot move it, two cars can be used to move it together. After the drug is injected into the human body, these two cars need to be merged to form