Scientists from The Scripps Research Institute have discovered a gene responsible for progressive hearing loss.
The has team found a gene, called Loxhd1, which is necessary for maintaining proper functioning hair cells in the inner ear.
However, mutations in this gene can lead to degradation of the hair cells and a disruption of the process that enables hearing.
"It is thought that mutations in several hundred genes can lead to deafness," said team leader Ulrich Mueller, a professor in the Department of Cell Biology and member of the Skaggs Institute for Chemical Biology at Scripps Research.
"However, for many forms of deafness, we don't know what effects the genes have. In this new research, we have linked a previously uncharacterized gene to deafness, first in mice and then in humans," said Mueller.
During the study, researchers used a technique called forward genetics in their quest to better understand the genetic basis of hearing and hearing loss.
In forward genetics, scientists make mutations at random in germ cells, screen the resulting models for physical characteristics of interest (in this case hearing impairment), then amplify these traits through the breeding of several generations.
The gene responsible for the trait is then identified through positional cloning.
In this case, the scientists were able to generate a new mouse line with hearing impairment that they called samba and then clone the gene responsible, Loxhd1, which had never before been associated with deficits in hearing.
When the mice inherited two copies of the mutated gene, they were profoundly deaf shortly after birth.
This is the third hearing-related gene that the Mueller lab has discovered.
"In humans, the prevailing difficulty is progressive hearing loss," he said.
"As you age, you lose your hearing slowly. Since this mutation can lead to progressive hearing loss, it provides us with more information on the genetic underpinnings of this condition and gives us clues as to how it might be corrected," he added.
The study appears in American Journal of Human Genetics, a publication of Cell Press.