Washington, Jan 4 (ANI): A gene that is required for proper development of the mouse inner ear may hold clues to human deafness.
In humans, the gene, known as FGF20, identified by researchers at Washington University School of Medicine in St. Louis, is located in a portion of the genome that has been associated with inherited deafness in otherwise healthy families.
"When we inactivated FGF20 in mice, we saw they were alive and healthy. But then we figured out that they had absolutely no ability to hear," said senior author David M. Ornitz, MD, PhD, the Alumni Endowed Professor of Developmental Biology.
The results show that disabling the gene causes a loss of outer hair cells, a special type of sensory cell in the inner ear responsible for amplifying sound.
While about two-thirds of the outer hair cells were missing in mice without FGF20, but the number of inner hair cells, the cells responsible for transmitting the amplified signals to the brain, appeared normal.
"This is the first evidence that inner and outer hair cells develop independently of one another," stated first author Sung-Ho Huh, PhD, postdoctoral research associate.
"This is important because most age-related and noise-induced hearing loss is due to the loss of outer hair cells," Huh stated.
As such, Ornitz and Huh speculate that FGF20 signalling will be a required step toward the goal of regenerating outer hair cells in mammals, the only vertebrates incapable of such feats of hearing restoration.
Ornitz and his colleagues also see evidence that mutations in FGF20 may play a role in human deafness. A genetic region known as DFNB71 has been associated with congenital deafness in a few human families.
"Based on our work, we are predicting that these families will have some sort of mutation in the FGF20 gene. It hasn't been found yet, but a group at the Baylor College of Medicine is sequencing this region of the genome to look for FGF20 gene mutations," Ornitz added.
The results were published online Jan. 3 in PLoS Biology. (ANI)