In the clinic, parents often ask, “We both have normal hearing and there is no deaf person in our family, why is our child deaf? How can it be genetic?” This is the question that most parents of children with congenital deafness ask, and it is the most common case of hereditary deafness. In the traditional understanding of the common people, there are people with poor hearing or deafness in every generation in the family such as grandfather, father, grandson, etc. Even uneducated people know that deafness is hereditary in their family. So why would a child be deaf when there are no deaf people in the family of either sex? Why would more than half be genetically deaf? To answer this question, it is important to first understand what is hereditary deafness? Hereditary deafness is divided into dominant and recessive inheritance. Usually, families with deaf people from generation to generation are usually dominant, and there is no deaf person in the family, but why would a deaf child be born? Most such families have recessive deafness. When both the father and mother carry the deafness gene, (for example, the father of a deaf child is born to the child’s grandparents, one of the grandparents carries the deafness gene but does not develop the disease, but passes the deafness gene to the child’s father, then the father also becomes a carrier but does not develop the disease, he If the child gets both the deafness gene from the father and the mother, forming a pure or compound heterozygote of the disease-causing mutation, then the deafness will occur. . Thus, children of a father and mother carrying the same disease-causing mutation have a 25% chance of acquiring both parents’ disease-causing mutations, resulting in a quarter of the children being born deaf. In addition, if such a couple has another child, the next generation will still have a 25% risk of developing deafness. The proportion of hereditary deafness in the total deaf population How many deaf people are hereditary deaf? According to the Second National Sample Survey of People with Disabilities in 2006, there are more than 27.8 million people with hearing and speech disabilities in China, including 20.04 million people with simple hearing disabilities, which is the highest number of all kinds of disabilities. In every 1000 newborns, there are 1-3 deaf children (congenital deafness), 65% of which are genetically deaf, and this percentage is increasing as more deafness genes are discovered. It is easy to see from the above data that genetic deafness is the leading cause of congenital deafness. In fact, the majority of congenital deafness and late-onset deafness are genetic disorders, and many drug-related deafness are also genetic disorders, even senile deafness in some sense. 3. What are the most common genes for hereditary deafness in the Chinese population? 1. GJB2 gene, which causes severe and profound deafness: up to 21.01% of deafness patients are deaf due to mutations in this gene. 2. SLC26A4 gene (PDS gene), which causes large vestibular canalicular syndrome, is detected in more than 15% of the deaf population. 3. Aminoglycoside antibiotic deafness-related genes: mtDNAA1555G and C1494T mutations: 3.43% and 1.03% of the deaf population carry them respectively. 4. Can hereditary deafness be treated? There is no effective drug treatment available. Wearing hearing aids or cochlear implants are effective treatments. V. Is there any significance in detecting hereditary deafness? Of course there is a significance. It can guide families who have already had a deaf child to have a prenatal diagnosis when they have another child, so that the tragedy of having another child with the same deafness does not happen again.