"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," says Dr. Liu. "Our findings emphasize the body's need for tight regulation of PRPP synthetase 1 since a drop in activity can lead to deafness." Other mutations in the PRPS1 gene have been linked to neurodegenerative disorders such as Arts syndrome and a form of Charcot-Marie Tooth disease, both of which feature deafness in the constellation of symptoms.

Knowing that a reduction in the amount of PRPP synthetase 1 is what causes deafness in DFN2, Liu and his colleagues are now exploring potential enzyme replacement therapies to either restore hearing or prevent further hearing loss in boys with DFN2. They believe that since the PRPS1 mutations can be used as a genetic marker for DFN2, in the future at-risk boys could be tested at birth and immediately put on enzyme replacement therapy to reduce or prevent the hearing loss that would ordinarily come later in life.

In addition, the knowledge that scientists gather about the mechanisms of PRPS1 potentially could be used to develop treatments to combat acquired hearing loss, such as the hearing loss caused by drugs that are used in some chemotherapy regimens and treatments for HIV/AIDS. These are powerful and helpful medications, but they have the unfortunate side effect of damaging, even killing, hair cells in the inner ear. The results from this study open the possibility for improving these life-saving treatments by eliminating or reducing the disabling side effect of hearing loss.

Source: NIH/National Institute on Deafness and Other Communication Disorders