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Found:Gene causing a rare hearing disorder

By
KELLY HEARN

ANN ARBOR, Mich., Nov. 20 (UPI) -- Researchers have found a gene they say causes a rare hearing disorder, one which renders a person incapable of hearing low-frequency sound.

The disease is known as low-frequency sensorineural hearing loss or LFSNHL. Researchers at the University of Michigan Medical School in Ann Arbor have determined LFSNHL results when a patient has one bad copy of the gene WFS1.

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Results of the study appear in the journal Human Molecular Genetics.

A person with LFSNHL cannot hear sound 2000 hertz and below and sometimes, because it does not interfere with human speech perception, a patient may not realize they have the disease, said Margit Burmeister, an associate professor of psychiatry and human genetics at the University of Michigan Medical School.

"Some of the patients in our study didn't know they had it until the study," said Burmeister. "Someone with LFSNHL might realize it after a rock concert, for example. A concert blows out high-frequency perception. In those cases most people would hear with their lower frequency hearing. But people with LFSNHL hear virtually nothing. Typically, once they get older there will be more common hearing loss."

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In a study involving six LFSNHL families, Burmeister and her collaborator, Dr. Marci Lesperance, also of University of Michigan Medical School, discovered children who inherit only one copy of the mutated gene WFS1 will gradually lose their capacity to perceive low-frequency sounds.

The WSF1 gene encodes a protein made up of 890 amino acids, the building blocks of proteins. The protein's function is complexly unknown, as is the means by which its mutations cause isolated low frequency hearing loss. It is produced in small amounts in the inner ear or cochlea, an area the researchers said is difficult to study.

"In each patient, the gene causes a change in only one of the 890 amino acids," Burmeister said. "Even though these mutations change just one, it is enough to produce progressive hearing loss."

The WSF1 gene also plays a role in Wolfram Syndrome 1, a rare but destructive condition that causes a number of physical abnormalities such as eye problems, diabetes and higher frequency deafness. People who inherit a mutated WFS1 gene from each parent, as oppose to only one in the case of LFSNHL, will have Wolfram Syndrome 1.

The researchers said more studies are needed to determine why the WFS1 selectively affects low frequency hearing while Wolfram Syndrome affects high frequency perception.

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They also suspect a connection between mutations in WFS1 and the more common types of hearing loss affecting high frequency sounds. They also are exploring a possible connection between WFS1 and Meniere's Disease, a common condition that causes occasional attacks of low-frequency hearing loss, vertigo and ringing in the ears.

"I think it's a good and interesting finding," said Donald Henderson, co-director of the center for hearing and deafness at the University of Buffalo in New York. "The results are not too surprising because people are often finding genes implicated in hearing loss. This is interesting because it is associated with low frequency loss, which clinicians don't find particularly often. For every low frequency case you find clinically, you'll find 50 to 100 high frequency cases."

Henderson said he is initially skeptical of claims that the gene might also be linked to Meniere's Disease.

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