Indian scientists find protein mutation linked to hearing loss in elderly

The team focussed on a fault in Cadherin-23 -- a protein essential for hearing in vertebrates.

The protein, which is embedded in inner ear hair cells, works by converting sound waves into electrical signals that the brain can interpret.

In mice studies, the team found that the mutated form of Cadherin-23 fails to unfold properly and causes disruption in sound transmission through the inner ear.

This led to progressive hearing loss in mice, said the team led by Sabyasachi Rakshit from the Insititute.

In the study, the team used a magnetic tweezer to expose the protein's three variants -- S47, V47 (natural variants), and P47 (mutant) -- to continual and oscillatory forces.

The scientists found that V47 tolerated the greatest force and slowly unfolded. In other words, it could withstand mechanical stress better.

While S47 exhibited intermediate stability, P47 unfolded quickly, tolerating the least force. It was more likely to remain unfolded, the reason behind its link to hearing loss.

Further, when subjected to repetitive force pulses that mimic natural mechanical stimuli in hearing, p47 exhibited less ability to tolerate repeated mechanical stresses. The results suggest a molecular basis for hearing impairments later in life.

The findings, published in the journal Nature Communications, will have potential use in hearing loss treatment by correcting the anomaly of the protein, said the researchers.

However, they noted that although the results may provide a mechanism for human hearing loss, they likely do not encompass the entire picture.

According to the World Health Organization (WHO), more than 1.5 billion people (nearly 20 per cent of the global population) live with hearing loss, while 430 million suffer disabling hearing loss.