Hearing and Deafness

Acoustic signals are essential for an animal’s
ability to respond appropriately to its environment.
Hearing is orchestrated by a large ensemble
of proteins acting in concert. Specialized
sensory cells in the cochlea of the inner ear
process the incoming sound waves, converting
them into cellular information that is relayed to
the brain via the acoustic nerve. A missing or
defective protein involved in the hearing
process results in hearing loss. Hearing loss is
common in humans. One out of 1000 newborns
lacks the ability to hear or has severely impaired
hearing. Two categories of genetic hearing loss
can be distinguished: nonsyndromic and syndromic.
In the former category the genetic defect
is limited to the ear; in the latter the ear is
one of several organ systems affected.
The types of genes implicated when defective as
the cause of nonsyndromic hearing loss include
those encoding proteins involved in cytoskeletal
structure, transcription factors, ion
channels (potassium channel), and intercellular
gap channels composed of junction connexins.