Scientists link genetic pathway to development of hearing

Located in the spiraled cochlea, the hearing portion of the inner ear, the hair cells transform the mechanical vibrations that enter the ear in the form of sound waves into chemical signals, which they then direct to the brain. Now researchers have found that the development of cochlea and hair cells is dependent on a genetic pathway called the PCP (planar cell polarity) pathway.

Although some species, including birds, are capable of re-growing hair cells, mammals lack the ability to naturally regenerate hair cells. Thus individuals born with improperly developed hair cells, or those who lose them through trauma, disease, environmental factors or aging, cannot regain their hearing.

By using mouse models the research team discovered that the PCP pathway is involved in shaping the cochlea and the sensory hair cells. Mutations within this genetic pathway impact the shape of the cochlea and the polarity of the sensory hair cells that are essential for hearing.

Scientists have been optimistic that by discovering the genes involved in development of the ear they could learn the molecular and genetic basis for some forms of deafness and offer promises for future efforts in hearing restoration.

Reports from the National Institutes of Health (NIH) indicate that severe hearing impairment affects 28 million Americans. That number includes the approximately 4,000 Americans each year who suffer from sudden deafness, and the roughly 12,000 children born each year with difficulty hearing.