In a new genome-wide association study, an international team led by neuroscientists from Keck Medicine of the University of Southern California (USC) in Los Angeles has found evidence that some people may be more genetically susceptible to noise-induced hearing loss than others. Noise-induced hearing loss is one of the most common work-related illnesses in the United States, according to the National Institute for Occupational Safety and Health (NIOSH), with troops in the Armed Forces being at especially high risk. In 2013, the Department of Veterans Affairs reported hearing loss as one of the most common disabilities among veterans receiving disability compensation.

Rick Friedman, MD, PhD

Rick Friedman, MD, PhD, Keck Medicine of USC

According to an article in the April 16, 2015 edition of the journal PLOS Genetics, the study authors say that those found to be at higher genetic risk for hearing loss may decide to take additional precautionary measures to protect their hearing prior to noise exposure.

“Understanding the biological processes that affect susceptibility to hearing loss due to loud noise exposure is an important factor in reducing the risk,” said senior study author Rick A. Friedman, MD, PhD, otologist, and professor of otolaryngology and neurosurgery at the Keck School of Medicine of USC. “We have made great advances in hearing restoration, but nothing can compare to protecting the hearing you have and preventing hearing loss in the first place.”

Immunostained mouse auditory nerve synapses after noise exposure

Immunostained mouse auditory nerve synapses after noise exposure. Courtesy Rick A. Friedman Lab

According to Keck Med USC, while gene association studies on noise-induced hearing loss in people have been conducted in the past, all were small and their results un-replicated. Genome-wide association studies, or GWAS, search the entire genome for common genetic variants to see if any are associated with a trait. Mouse GWAS have led to the discovery of hundreds of genes involved in complex traits that have immediate relevance to people, say the study authors.

In the Keck Med USC study, conducted at the Zilkha Neurogenetic Institute, Friedman’s team identified the Nox3 gene—almost exclusively expressed in the inner ear—as a key gene for susceptibility to noise-induced hearing loss. Using 64 of the 100 strains of mice in the Hybrid Mouse Diversity Panel, the team was able to increase the statistical power of its investigation, leading to the first published GWAS for noise-induced hearing loss in mice. The study authors say that more research is necessary before clinical recommendations can be made.

The study was conducted in collaboration with scientists from Brazil’s Federal University of Rio Grande do Sul, and UCLA.

Source: Keck Medicine of USC

Photo credits: Keck Medicine of USC, Rick A. Friedman Lab