Usher’s syndrome is a disease that affects both hearing and sight.
A patient who is suffering from Usher’s syndrome is born with a certain degree of hearing loss which may vary from person to person genetically. Usher syndrome, is a rare genetic disorder caused by a mutation in any one of at least 11 genes.
Usher syndrome may also be referred to as Retinitis Pigmentosa. Usher syndrome is a rare disease.
Some of the patients are congenitally deaf and are suffering from progressive visual loss caused by Retinitis Pigmentosa. This syndrome may exist in profoundly deaf children to a degree of 10 per cent.
Retinitis Pigmentosa affects the retina. The retina is the part of the eye which processes light and transmits information through the optic nerve to the brain. As Retinitis Pigmentosa develops, the retina slowly begins to degenerate, which will then affect the vision.
In the first stages, night vision is usually affected, leaving the person night blind. After some time, the daytime vision will be affected, as well.
It is currently believed that there are two main forms of Usher syndrome. One of them is characterised by profound deafness and poor balance. Retinitis Pigmentosa is normally present in a child under the age of 10. In another form of Usher syndrome, patients will be suffering from partial hearing loss, and Retinitis Pigmentosa will be present before the patient reaches 20 years of age. For people with this kind of Usher syndrome, hearing aids can be of great value.
What are the different types of Usher syndrome?
Type 1 and type 2 are the most common forms of Usher syndrome in the United States. These 2 types account for about 95% of all cases of Usher syndrome.
Babies born with Type 1 Usher syndrome:
- Are almost totally deaf at birth.
- Have severe balance problems.
- Sit without support at a later
- age than normal (normal is at 6 – 9 months old).
- Are late walkers (18-24 months).
- Develop vision problems before age 10, usually in early childhood.
- Begins with night vision problems.
- Progresses quickly to total blindness.
- May not benefit from hearing aids (devices that make sound louder). They may be candidates for cochlear implants (a surgically placed device that sends sound directly from ear to stimulate the hearing nerve).
Babies born with type 2 Usher syndrome:
- Have moderate to severe hearing loss at birth.
- Have normal balance.
- Can benefit from hearing aids.
- Develop night vision problems as teenagers.
- Progresses more slowly.
- Does not result in total blindness.
Babies born with type 3 Usher syndrome:
- Have normal hearing at birth.
- Have almost normal balance.
- Sometimes have balance problems later on.
- Have gradual hearing and vision loss.
- Rate of loss differs among children.
- Hearing loss is apparent by teens.
- Can benefit from hearing aids after hearing loss begins.
- Night blindness starts in puberty.
- Blind spots occur by late teens/young adulthood.
- Total blindness by middle age.
What causes Usher syndrome?
Scientists now know that Usher syndrome is inherited, which means it is passed from parents to children, and is caused by changes, called mutations, in genes. Genes are the chemically coded instructions in cells that tell cells what to do. The human body contains 20,000 to 25,000 genes. Every person has two copies of each gene, one from each parent.
Usher syndrome is an autosomal recessive disorder.
- Males and females can both be affected by the condition.
- Both parents carry a mutated gene but do not have Usher syndrome themselves.
- A baby can get either the mutated gene or the normal gene from each parent.
- A child who gets a mutated gene from each parent will have Usher syndrome. The chance that a child from two parents who each have an Usher gene will have Usher syndrome is 1 in 4.
What causes vision loss in Usher syndrome?
The retina is a tissue at the back of the eye that is needed for vision. The gene mutation in Usher syndrome affects the retina’s light-sensing cells called rods and cones. In RP, the retina’s light-sensing rods and cones slowly go bad, starting at the outer edges. As RP gets worse, the person loses peripheral (edges) vision first then central vision.
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