Study Works To Find Impact Of Supplements On Genetic Hearing Loss

Study in mice shows promise using antioxidant regimen

An enhanced diet helped reduce hearing loss in mice with the genetic mutation most commonly responsible for childhood deafness, new research suggests.

The study found that an antioxidant regimen of beta carotene (precursor to vitamin A), vitamins C and E and magnesium helped slow progression of hereditary deafness in the mice with a connexin 26 gene deletion. Mutations in this gene are a leading cause of genetic hearing loss in many populations.

Meanwhile, the enhanced diet had the opposite effect on another mutant mouse modeling AUNA1, a rare type of hearing loss, according to the research from University of Michigan’s Kresge Hearing Research Institute and U-M’s C.S. Mott Children’s Hospital.

The findings appear in Scientific Reports from the publishers of Nature.

“Many babies born with a genetic mutation that causes deafness pass their newborn screening test but then lose their hearing later in life,” says author Glenn Green, M.D., associate professor of pediatric otolaryngology at C.S. Mott Children’s Hospital.

“These patterns suggest that for some children, there may be an opportunity to potentially save cells present at birth. For these childhood cases it’s crucial that we identify therapies that prevent progression and reverse loss of hearing.

“Our findings suggest that a particular high dose of mineral and vitamin supplements may be beneficial to one genetic mutation,” adds senior author Yehoash Raphael, Ph.D., professor in the Department of Otolaryngology-Head and Neck Surgery at the University of Michigan Medical School. “However, the negative outcome in the AUNA1 mouse model suggests that different mutations may respond to the special diet in different ways.”

Scientists injected gene therapy via a virus carrying the corrected gene for the whirlin protein into the inner ear of mice with the whirlin mutation (whirler mice). Although the gene therapy had minimal effect on treated adult whirler mice, the scientists found that gene therapy in newborn whirler mice restored stereocilia to their normal length and eliminated some of the extra rows of stereocilia. In addition, more hair cells survived in the treated ear as compared to the untreated ear in the same mouse. Unfortunately, mice that received gene therapy demonstrated no improvement in hearing ability when tested one to three months after treatment.

Now the scientists will try to determine why correcting the architecture of the stereocilia and improving the survival of the hair cells does not restore hearing ability in whirler mice. They will also work to improve gene therapy.

This work was supported within the intramural laboratories of the NIDCD (grants 1ZIADC000082-03, 1ZIADC000079-04, and 1ZIADC000039-18.) Dr. Chien is supported by the NIDCD Otolaryngology Surgeon-Scientist Program. The NIDCD Mouse Auditory Testing Core Facility provided additional support.


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