Progressive Hearing Impairment can also be Caused by a Gene

A gene is also responsible for hearing impairment at a young age, apart from noise, researchers revealed.

Mutations of the SMPX (small muscle protein) gene, located on the X chromosome have been found to be responsible for the loss of hearing.

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The study is believed to make diagnosis of progressive hearing impairment easier and may also provide a beginning for the development of new treatment methods.

Researchers explained that when sound waves reach the snail-shaped structure of the inner ear, sensory cells are activated.

However, if the hair-like cilia of such cells are damaged by a mutation of the SMPX gene, they can no longer respond to acoustic stimuli.

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"In our study, we succeeded in demonstrating for the first time that SMPX is very active in the inner ear," said Vera Kalscheuer, a scientist at the Max Planck Institute for Molecular Genetics.

The researchers were surprised to discover that the gene not only plays an important role in skeletal muscle and in the heart but also in the inner ear.

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The fact that the mutation only affects the hearing, while the function of the muscles and heart is not impaired also astonished experts.

To confirm the findings, researchers examined a family that had experienced hereditary hearing impairment across five generations.

In order to carry out a targeted search for gene mutations, they concentrated and sequenced all genes of the X chromosome. This led to the discovery of the base substitution in the SMPX gene in all of the family members affected by the hearing impairment.

The researchers encountered a second mutation in the course of their analysis which also leads to deafness.

Source-ANI