Researchers at the University of Antwerp have identified three genes, involved in potassium ion channels in the inner ear, which are essential for normal hearing protection. Defects in these genes have been shown to significantly decrease the cochlea's ability to protect itself from noise-related injuries. (More below the fold....)
The team pinpointed the genes during a study of over 1000 Swedish men who had all been exposed to loud noises while working in factories. 80% of these participants had been subjected to this noise for at least 20 years. The teams tested the mens' hearing thresholds as well as performed a genetic analysis of the 10% of the group who were most sensitive to noise and the 10% who were the most resistant to noise. Their hypothesis was that certain genes which are important for proper functioning of hair cells, and protect them from noise injuries, may have a mutation in the group with the highest sensitivity to noise.
"Significant differences between the susceptible and resistant workers were found in the sequence of three genes KCNE1, KCNQ1 and KCNQ4," said Van Camp [the principal investigator] who reported the findings in the journal Human Mutations."Further studies of KCNE1 show the version of the gene associated with increased risk to noise causes the encoded ion channel to open more rapidly than the normal version," he added in a statement.
This suggests that a hyper-active potassium ion channel results in an imbalance of the unique ion gradient which allows hair cells to function. Too much potassium may result in toxicity to the cell, resulting in increased likelihood of hair cell death and hearing loss.
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