Genes that control cell death fingered in age-related he...(ess. In addition to genetics other facto...)

"Age-related hearing loss is a very serious problem for patients, and it's also challenging for scientists who study it," said Frisina. "There are many potential reasons. It could be a problem in the brain, or the problem could rest with any number of cells in the inner ear. The causes are more complicated than in a condition like Parkinson's disease, where we know exactly which type of cell dies in which part of the brain."

To begin to understand the genetics of human hearing, the group has been charting the activity of more than 22,000 genes in mice, comparing young mice to their older counterparts. In the study in Apoptosis, the team used two different methods to study gene expression, thanks to funding from the National Institute on Aging and the National Institute on Deafness and Other Communication Disorders, both part of the National Institutes of Health.

First, scientists put more than 300 genes through a broad gene-array study, looking at genes whose activity in the inner ear differed greatly between normal mice and those with hearing loss. Then the team narrowed its focus to 35 such genes, employing a newer technique known as a PCR array to measure activity. Through that test the scientists identified eight genes, all part of the apoptotic process, whose activity differed between the two groups.

Apoptosis itself is certainly nothing new. Such programmed cell death happens constantly it's the body's way of getting rid of cells that are damaged or no longer needed. When apoptosis happens, a cell's structure breaks up, and the cell disintegrates, with the cell "blebbing," or bulging outward, ultimately blowing apart. It's a
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