Mutated Muscle Protein Can Cause Deafness

Researchers have previously identified over 50 genes with different functions that are considered possible causes of hereditary hearing loss.  However, researchers at he Max Planck Institute for Molecular Genetics have recently discovered a previously unknown genetic cause of progressive hearing loss.  This disease is caused by a gene on the X chromosome which is due to mutations of the small muscle protein (SMPX) gene.  The SMPX gene plays an active role in the skeletal muscle and heart, but is also active in hearing.

Interestingly, the researchers also found that mutations on SMPX only effects the hearing while the function of the heart and muscles are not disturbed.  The article states, "when sound waves reach the snail-shaped structure of the inner ear, sensory cells are activated.  If hair-like cilia in the inner ear are damaged from mutations on SMPX, they cannot respond to acoustic stimuli" (see image).  Such damages to the ear are caused by premature stop codons as a result of the mutations on SMPX.  I find it interesting how a mutation on the SMPX gene can result in hearing loss but does not have any effect on the heart or skeletal muscles.  While it leads to hearing impairments, I guess we should actually be lucky the mutations do not harm our muscles and heart, which could possibly lead to serious health issues.

[caption id="attachment_4675" align="aligncenter" width="289" caption="Image of the inner ear"][/caption]