July 5, 2006
Genetic Link Found to Noise-Induced Hearing Loss
LONDON -- Belgian scientists have pinpointed three genes which could explain why some people exposed to loud noise suffer hearing loss.
The genes discovered by Professor Guy Van Camp and researchers at the University of Antwerp are involved in the recycling of potassium in the inner ear, which is essential for normal hearing.
Dr Ralph Holme, of Britain's national charity for the deaf and hard of hearing RNID, which funded the research, described the finding as a very exciting breakthrough.
"This discovery could revolutionize the way this common form of hearing loss is prevented and treated in the future," he said in a statement on Wednesday.
Van Camp found the genes while studying more than 1,000 men who had been exposed to loud noise while working in paper pulp mills and steel factories in Sweden. Nearly 80 percent had been subjected to noise for at least 20 years.
After testing the men's hearing, the scientists did a genetic analysis of the 10 percent who were most sensitive to noise and an equal number who were most resistant and compared the results.
"Significant differences between the susceptible and resistant workers were found in the sequence of three genes KCNE1, KCNQ1 and KCNQ4," said Van Camp 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.
The defect could make people more sensitive to noise.
Noise induced hearing loss (NIHL) is caused by sounds ranging from 120 to 150 decibels. Motorcycles, firecrackers and guns emit sounds in that range, according to the National Institute on Deafness and other Communication Disorders (NIDCD) in the United States.
Heavy city traffic noise can be about 85 decibels. Noise measuring less than 80 decibels, even after long exposure, is unlikely to cause hearing problems.
Loud noise is an attributable cause at least in part in about one-third of the 28 million Americans who have some degree of hearing loss.
More than a million Britons are at risk or have already experienced hearing loss due to loud noise, the RNID said.