Gene Could Helps Scientists Understand Genetic Deafness
January 4, 2012

Gene Could Helps Scientists Understand Genetic Deafness

Researchers at Washington University School of Medicine report they have found new clues that may help scientists understand the genetic causes of deafness.

The gene FGF20 has been associated with inherited deafness in otherwise healthy families.  The FGF20 gene codes for one member of a family of proteins known as fibroblast growth factors.

Members of this family are known to play important and broad roles in embryonic development, tissue maintenance and wound healing.

"When we inactivated FGF20 in mice, we saw they were alive and healthy," senior author David M. Ornitz, MD, PhD, Professor of Developmental Biology, said in a press release. "But then we figured out that they had absolutely no ability to hear."

The team found that disabling the gene causes a loss of outer hair cells, which is 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, the number of inner hair cells appeared to be normal.

"This is the first evidence that inner and outer hair cells develop independently of one another," first author Sung-Ho Huh, PhD, postdoctoral research associate, said in a press release. "This is important because most age-related and noise-induced hearing loss is due to the loss of outer hair cells."

The team believes that FGF20 signaling will be a required step toward regenerating outer hair cells in mammals.  They found that this signaling must occur on or before day 14 of the embryo's development to produce a normal inner ear.

The team also said they see evidence that mutations in FGF20 may play a role in human deafness, which is another open question being investigated.

The research was published in the open-access journal PLoS Biology on January 3, 2012.


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