Deafness and hearing loss have many different causes including infection, traumatic injury and genetic makeup. With increased knowledge of the human genome, it is becoming possible to identify specific genes involved in such conditions. One of the genetic causes is a change in the coding of the gene called DFNA5.
DFNA5 is the official symbol of the gene with the official name “deafness, autosomal dominant 5". This gene resides on the short (p) arm of chromosome 7 at position 15. It codes for the DFNA5 protein, which is important in the building of the cochlea.
The cochlea is a small snail-shaped structure in the inner ear. The cochlea converts sound waves into nerve impulses. After the sound waves pass through the outer and middle ear, it transforms the energy into fluid motion, which disturbs sensory cells with hair-like structures within the cochlea. Movement of the hair-like structures on the sensory cells triggers activity in hearing nerve fibers. The activation of the auditory nerve sends messages to the part of the brain allowing the interpretation of the sound impulse.
Persons with certain mutations in the DFNA5 gene produce smaller lengths of the DFNA5 protein, which affects the function of that person's cochlea. The exact action of the DFNA5 protein within the cochlea is currently unknown; however, it is believed to have an important function in the development and maintenance of the cochlea. At least three mutations in the DFNA5, which lead to deafness, are currently recognized.
Mutations in the DFNA5 gene cause a condition known as non-syndromic deafness this is a hearing loss without any other signs or symptoms affecting other parts of the body. The significance of the DFNA5 in non-syndromic deafness has been ascertained from genetic studies of families with this condition. From this research, genetic testing for the condition is now available.
According to Genetics Home Reference, other names seen in scientific literature on this condition include deafness, autosomal dominant 5 protein, DFNA5 Human, ICERE-1, Inversely correlated with estrogen receptor expression 1 and non-syndromic hearing impairment protein.
People with non-syndromic deafness caused by mutations in the DFNA5 experience a progressive hearing loss. This hearing loss resembles age-related hearing loss (presbyacusis). However, people with mutation in the DFNA5 gene experience their hearing loss at an earlier age in to people without a DFNA5 mutation.
Deafness is an invisible and isolating condition. An awareness of the causes of deafness and its affects by the hearing community, aids persons with this condition to achieve integration that they deserve.