Usher Syndrome
What is Usher syndrome?
Usher syndrome is a genetic disorder that is characterized by hearing impairment as well as an eye disease called retinitis pigmentosa in which vision degenerates (gets worse) over time. Some people with Usher syndrome also have balance problems.
How common is Usher syndrome?
Usher syndrome is the most common condition (aside from aging) that affects both hearing and vision. More than half of all deaf-blind people in developed countries (such as the US, Canada, and France) have Usher syndrome.
How is Usher syndrome inherited?
The syndrome is transmitted (passed along) in families by autosomal recessive inheritance, which requires the presence of two copies of the Usher gene for the disorder to be manifest. Each parent of a boy or girl with Usher syndrome is a "carrier" with one standard and one mutated Usher gene but no sign of the syndrome. A child with the syndrome has it because he or she received two mutated Usher genes, one from each of the carrier parents.
The parents' risk with each future pregnancy is:
- 1 in 4 (25%) that the child will have two mutated Usher genes and have the syndrome
- 2 in 4 (50%)that the child will have one mutated Usher gene and one standard gene and be an unaffected carrier
- 1 in 4 (25%) that the child will have two standard and no Usher gene.
If a normal child from an Usher family marries more or less at random (they don't marry someone from another known Usher family), the risks for their offspring of Usher syndrome are less than 1%. (Assuming a gene frequency in the general population of 1%, the risks are 2/3 X 1/100 X 1/4 = 1/600.)
Next: Three types of Usher syndrome »
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From the Doctors at MedicineNet.com  |
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- Electroretinography - Read about electroretinography (ERG), an eye test where electrodes placed on the cornea measure electrical responses to light to try to detect abnormal retinal function. Source:MedicineNet
- Deafness, Hearing Loss - Hearing loss (deafness) may be present at birth or it may manifest later in life. Deafness may be genetic or due to damage from noise. Treatment of deafness depends upon its cause. Source:MedicineNet
- Read 13 more Usher Syndrome related articles ...
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Last Editorial Review: 5/11/2002