Usher syndrome is a genetic condition that causes serious hearing and vision loss. It is an inherited condition passed from parents to their children genetically, and is estimated to occur in at least four in one hundred thousand people. It affects males and females equally and is thought to be responsible for between three and six percent of all childhood deafness and about fifty percent of deaf-blindness in adults.
Usher syndrome is called a recessive genetic condition because a person must have a pair of mutated genes, one from each parent, for the condition to manifest itself. Researchers have identified three different types of Usher syndrome.
Usher Syndrome Type 1
A child with Type 1 Usher's Syndrome is either profoundly deaf or has severe hearing impairment at birth. As the child grows, balance problems may become apparent and speech abnormalities may develop.
Symptoms of the eye disease, retinitis pigmentosa, will also begin in either childhood or early adolescence.
Usher Syndrome Type 2
Usher Syndrome Type 2 is characterized when a child is born with mild to moderate hearing impairment. The level of hearing loss remains the same but the symptoms of retinitis pigmentosa often become apparent by late adolescence.
There are no balance problems as in type 1.
Usher Syndrome Type 3
Sufferers of Usher Syndrome Type 3 will experience the progressive loss of hearing together with loss of vision as a result of retinitis pigmentosa.
Typically, a child with Usher Syndrome will develop a gradual decline in vision initially resulting in a form of night-blindness. Visual perception and field of view will continue to decrease as the child grows older.
By the age of about thirty, vision problems increase rapidly when cataracts form and the lens of the eye becomes opaque because of them. The visual field may have narrowed down to around ten degrees by the time the sufferer reaches about forty years of age. Normal field of vision is between sixty and eighty degrees.
Usher Syndrome Prognosis
Although there is no cure for Usher's Syndrome, it is possible to treat sufferers with hearing aids, corrective eyeglasses and education designed to help them live with diminished senses.
Experimental treatment using gene therapy shows some promise with the potential of being able to prevent the loss of hearing and sight in this devastating condition. However, a lot more developmental work and testing needs to be carried out before such treatment can be administered to human patients.