Deafness Sometimes Caused by Mutated Protein

According to German investigators at the Max Planck Institute for Molecular Genetics (MPIMG), in Berlin, it would appear that deafness can sometimes be caused by a mutated muscle protein, rather than simply by prolonged exposure to loud noises.

In a large number of deafness cases, the condition is brought on by genetic factors, researchers say. Mechanical or external stimuli only cause the disease in specific individuals, and at certain ages.

When it comes to young adults and children, genetic causes are oftentimes to blame. Now, MPIMG researchers and colleagues from Nijmegen managed to identify a new cause that falls in this category.

They say that mutations of the SMPX (small muscle protein) gene can lead to deafness. The gene can be found on the X chromosome, and experts had no idea that it's also involved in hearing until now.

The gene is known to be active in controlling skeletal and heart muscles, but this was the known extent of its actions. With the new knowledge, experts hope to become better prepared in diagnosing progressive hearing impairment.

At the same time, the datasets could be used to start research for developing new avenues of treatment for deafness. Some types of hereditary hearing loss could finally be addressed in this manner.

“In our study, we succeeded in demonstrating for the first time that SMPX is very active in the inner ear. Our discovery makes hearing impairment easier to diagnose,” explains Max Planck scientist Vera Kalscheuer.

“Up to now, we could only speculate about the function of the SMPX protein. When we know the precise mechanism at work here, we can carry out further research and possibly develop new treatment options,” she goes on to say, quoted by AlphaGalileo.

The scientist and her team are now planning to conduct a series of functional tests, which may finally reveal the exact nature of effects the SMPX protein has on hearing. The latest studies could not establish this for certain.

Interestingly, the effect that this molecule has is caused by a single, missing base pair in its gene. This mutation leads to a stop codon, whose presence renders the protein useless. Without it, hearing is damaged, though researchers don't know exactly what underlies this correlation.