Scientists identify gene linked to rare form of deafness

Washington: Scientists have identified a gene associated with a rare form of progressive deafness in males.

Seemingly, the gene, PRPS1, is significant for inner ear development and maintenance.
The gene is associated with DFN2, a progressive form of deafness that primarily affects males.

Boys with DFN2 begin to lose their hearing in both ears roughly between the ages of 5 and 15, and over the course of several decades will experience hearing loss that can range from severe to profound.

The international team of researchers funded by the National Institute on Deafness and Other Communication Disorders found that the PRPS1 gene encodes the enzyme phosphoribosylpyrophosphate (PRPP) synthetase 1, which produces and regulates PRPP (phospho-ribosylpyrophosphate), and appears to play a key role in inner ear development and maintenance.

The four mutations identified in the PRPS1 gene cause a decrease in the production of the PRPP synthetase 1 protein that results in defects in sensory cells (called hair cells) in the inner ear, and eventually leads to progressive deafness.

Xue Zhong Liu, M.D., Ph.D., lead author of the study and from the University of Miami Miller School of Medicine said: "PRPS1 is an interesting example of a human disease gene in which gain of function or loss of function mutations cause several different and distinct hereditary disorders.

"Our findings emphasize the body``s need for tight regulation of PRPP synthetase 1 since a drop in activity can lead to deafness."

The experts are now researching on potential enzyme replacement therapies to either restore hearing or prevent further hearing loss in boys with DFN2.

James F. Battey, Jr., M.D., Ph.D., director of the NIDCD concluded: "This discovery offers exciting therapeutic implications. "Not only does it give scientists a way to develop a targeted treatment for hearing loss in boys with this disorder, it may also open doors to the treatment of other types of deafness, including some forms of acquired hearing loss."

The findings are published in the Dec. 17 early online issue of the American Journal of Human Genetics.