Researchers Discover Gene Defect Linked to Deafness

Genetic mutation associated with hearing loss in Usher syndrome type 1 and other cases, study says.

MONDAY, Oct. 1 (HealthDay News) -- Researchers who have identified a genetic mutation that causes deafness say that the findings could one day lead to the development of new treatments for those at risk for a certain type of hearing loss.

In their new study, scientists at the University of Cincinnati and Cincinnati Children's Hospital Medical Center reported that the gene is associated with hearing loss stemming from Usher syndrome type 1, a condition that also causes night-blindness and a loss of peripheral vision due to retinal degeneration, as well as some cases of hearing loss not associated with the syndrome ("non-syndromic deafness").

"In this study, researchers were able to pinpoint the gene which caused deafness in Usher syndrome type 1 as well as deafness that is not associated with the syndrome through the genetic analysis of 57 humans from Pakistan and Turkey," lead investigator Zubair Ahmed, an assistant professor of ophthalmology who conducts research at Cincinnati Children's, said in a university news release.

Ahmed explained that deafness in Usher syndrome type 1 and non-syndromic hearing loss has been linked with mutations affecting a protein, known as CIB2, which attaches to calcium inside a cell. "To date, mutations affecting CIB2 are the most common and prevalent genetic cause of non-syndromic hearing loss in Pakistan," Ahmed said. "However, we have also found another mutation of the protein that contributes to deafness in Turkish populations."

In animal studies, CIB2 has been found in the hair cells of the inner ear that respond to fluid motion and allow hearing and balance. CIB2 is also found in retinal photoreceptor cells, making vision possible, the researchers noted in the news release.

The new findings provide more insight into mechano-electrical transduction, or the process that enables the ear to convert mechanical energy -- or energy of motion -- into something the brain can recognize as sound, the researchers pointed out.

"With this knowledge, we are one step closer to understanding the mechanism of mechano-electrical transduction and possibly finding a genetic target to prevent non-syndromic deafness as well as that associated with Usher syndrome type 1," Ahmed concluded in the news release.

The study, which also involved researchers from the U.S. National Institute on Deafness and other Communication Disorders (NIDCD), Baylor College of Medicine and the University of Kentucky, was published in the Sept. 30 online edition of Nature Genetics.

It's estimated that 3 to 6 percent of deaf children and 3 to 6 percent of children who are hard-of-hearing have Usher syndrome. In the United States, roughly four out of every 100,000 babies have the syndrome.

More information

The U.S. National Library of Medicine has more about Usher syndrome.