March 11, 2011

Genetic Deafness Syndrome

(Ivanhoe Newswire) -- Ten years ago, research scientist began trying to understand how a specific feature of a cell called an L-type calcium channel might be related to genetic deafness syndrome.

This specific feature created a knockout mouse missing both copies of the CACNA1D gene; a gene which makes protein, and allows calcium to flow into other cells.

The CACNA1D gene is also important in relaying important instructions from one cell to another. Although the knockout mouse was created without the CACNA1D gene, it was still able to live a normal life span, but its heart beat was slower than average, and arrhythmic. The knockout mouse was also completely deaf.

At the 55th Annual Biophysical Society Meeting which took place on March 9, 2011, an international team of researchers lead by Hanno Bolz of the University of Cologne in Germany identified a mutation on the CACNA1D gene. This mutation of the gene causes an extra amino acid to be added to the middle of protein, and may be the missing link in identifying genetic deafness syndrome.

 Members of two different families in Pakistan have been identified as carrying the mutated CACNA1D gene. These members carry two copies of the mutated gene, and are also completely deaf with an irregular heartbeat.

Joerg Striessnig, professor at the University of Innsbruck in Austria, and senior study author was quoted as saying "their heart beats slowly, dropping below 30 beats a minute during sleep."

Striessnig also notes that the families' mutated gene does not destroy the protein, but instead, sits still on the cells surface membrane where it should be.

"It's not only interesting for medicine but also for understanding how these channels work as molecular machines," he was quoted as saying.

Source: American Institute of Physics, published online March10, 2011