Congenital deafness is hearing loss that occurs at birth. It is also called congenital deafness syndrome and can be inherited or acquired. It can be conductive (hearing loss caused by a blockage in the middle ear) or sensorineural (hearing loss that affects the nerves to the brain).
The most common cause of congenital deafness is hereditary, meaning that it is present due to a mutation in a specific gene. There are different types of genetic deafness, ranging from dominant to recessive and X-linked. Hereditary congenital deafness is the most common type and affects about 2% of the world’s population.
There are more than 180 genes associated with hearing loss. Some of these genes are very important and contribute to the development of the cochlea, a part of the inner ear that allows hearing. Others are less important, but can still play a role in the onset and severity of hearing loss.
Occasionally, a mutation in one of these genes may result in deafness, but it can only be detected by testing the child’s DNA for the gene. This is a very sensitive test that can detect mutations in up to 25% of newborns with hearing loss, and can help determine the type of deafness.
Other causes of hereditary congenital deafness include prenatal infections, toxins consumed by the mother during pregnancy and other conditions that occur in the baby’s first weeks of life or shortly after birth. These conditions can cause mild to profound sensorineural hearing loss, with the most common being a condition that affects both ears, known as bilateral symmetrical deafness.
Hereditary hearing loss is more common in people who have one parent with normal hearing and a single copy of the defective gene. It is also possible to have one parent with a hearing impairment and one parent who has normal hearing, in which case, the chance of the child having hearing loss is 50%.
Syndromic hereditary congenital deafness can also occur, although it is much rarer than non-syndromic deafness. It can be the result of a mutation in a gene that codes for proteins that are important for the physiology of the ear or brain.
These proteins are important for hearing by helping to change sound into nerve signals that go from the ear to the brain. They are produced by cells in the inner ear and the brain. The abnormal proteins can interfere with the function of these cells and lead to hearing loss.
Some of these alterations in the ear’s physiology can be corrected by surgery. This is sometimes called cochlear implantation, and can provide a partial or complete recovery of hearing for some children.
Other therapies include speech therapy, which can help to improve communication skills and quality of life for a child who is deaf. However, these treatments have limited effectiveness and cannot restore full hearing.
In addition, it can be difficult for a deaf child to learn and communicate. Therefore, it is important that the child is evaluated and receives early intervention to prevent further hearing losses.
