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Deafness

Deafness

Deafness

Description
 Deafness can be mild, moderate, severe, or profound. People with mild deafness have some difficulty following speech, mainly in noisy situations. Those with moderate deafness have difficulty following speech without a hearing aid. Those who are severely deaf rely a lot on lip-reading, even with a hearing aid. Sign Language may be their first or preferred language. Profoundly deaf people communicate by lip-reading. Sign Language may be their first or preferred language. Hearing loss may result from damage or disruption to any part of the hearing system: from simple wax blocking the ear canals, through to age-related changes to the sensory cells of the cochlea, to damage to the brain. Common causes of deafness in adults include presbyacusis (age-related hearing loss), side-effects of medication, acoustic neuroma, and Meniere"s disease. Common causes of deafness in children include inherited conditions, infection during pregnancy, meningitis, head injury, and glue ear.

Who is at Risk?
 The commonest cause of hearing loss is ageing, and three quarters of those with deafness are aged over 60. From 40 years old, more men than women become hard of hearing.

Source: BBC Health

Scientists Find Deafness Gene"s Function
 A group of scientists at TSRI, UCSD, the Oregon Hearing Research Center and Vollum Institute at Oregon Health & Science University has discovered a key molecule that is part of the machinery that mediates the sense of hearing. The team, that included TSRI Associate Professor Ulrich Mueller, Ph.D., a member of TSRI"s Institute for Childhood and Neglected Diseases, found that a protein called cadherin 23 is part of a complex of proteins called "tip links" that are on hair cells in the inner ear. Mutations in the gene cause deafness as well as Usher syndrome, the leading cause of deaf-blindness.

The team"s research explains how the cadherin 23 gene is a direct cause of certain types of deafness and suggests a potential therapeutic target for treating deafness. Childhood and age-related hearing impairment is a major issue in our society. One in three people older than 60 and about half of all people over 75 suffer some form of hearing loss. And about four out of every 100,000 babies born in the United States have Usher syndrome. Age-related hearing loss may be related to problems in the tip links. Point mutations in the cadherin 23 protein have been associated with age-related hearing loss in mice.

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