Research reveals genetic mutation associated with early-onset adult deafness in Rhodesian Ridgebacks

Tatiana Katsai / stock.adobe.com

Embark Veterinary, Inc scientists have discovered that a genetic mutation in the EPS8L2 gene is associated with early-onset adult deafness (EOAD) in Rhodesian Ridgebacks.

According to a company release, early-onset adult deafness can cause dogs to lose their hearing by 1 to 2 years old, and some purebred Rhodesian Ridgebacks lose their hearing when they're as young as 4 months old. This is particularly upsetting for this breed renowned for thriving at and finding satisfaction in competitive dog sports and hunting.

This breakthrough discovery has derived from more than a decade of research and collaboration between breeders, dog owners, and scientists. Mark Neff, PhD, Embark senior director of scientific discovery, and his colleagues at the UC Davis Veterinary Genetics Lab, revealed a genetic connection between EOAD and canine chromosome 18 in 2009. However, not until Embark joined forces with the Rhodesian Ridgeback Club of the US—the nonprofit organization projectDOG—and Rhodesian Ridgeback dog owners that a genome-wide association study was performed on 185 Rhodesian Ridgeback dogs, using 220K+ genetic markers.

This analysis localized the genetic connection to the EPS8L2 gene, and further DNA sequencing and genotyping detected a deletion perfectly predictive of the disorder. Because the mutation is recessive, both sire and dam must be carriers of it for offspring to acquire EOAD, according to the release.

"When we started this research over 10 years ago, we knew a discovery in early-onset adult deafness – one of the most common disabilities in humans and dogs – could provide valuable tools for life science companies using regenerative medicine to develop therapeutics for childhood hearing disorders," said Neff.

"Embark's health discovery engine – fueled by customer participation in research like our annual health survey – is not only crucial for determining the genetic links to canine health conditions, but could ultimately lead to human health discoveries as well,” he added.

When it is identified early on that a dog will ultimately lose his hearing, owners, breeders, and veterinarians can take proactive measures surrounding their dog's care. This can consist of training using visual cues rather than sounds, adding tags to leashes and collars identifying the dog as deaf, and avoiding to startle the dog. Ridgebacks actually typically cope well with this type of heritable deafness, particularly if they have a hearing dog housemate whose cues they can follow.

"The single constant in the decade-long search for this mutation has been the dedicated breeders who painstakingly worked with their puppy owners to provide the samples that made this discovery possible," said Denise Flaim, former co-chair of the Rhodesian Ridgeback Club of the United States Health and Genetics Committee, who first approached Neff about starting the research in 2009.

"This is a long awaited tool for Ridgeback breeders, but it should be used wisely. Now we can identify carriers, which can be bred safely to non-carriers, to maintain genetic diversity and confidently produce hearing offspring,” she concluded.

Reference

Embark discovers mutation associated with breed-specific hearing loss, in first-ever canine health discovery using commercial testing genetic data. News release. Embark Veterinary, Inc. March 2, 2022. March 3, 2022. https://www.prnewswire.com/news-releases/embark-discovers-mutation-associated-with-breed-specific-hearing-loss-in-first-ever-canine-health-discovery-using-commercial-testing-genetic-data-301493085.html