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(Synonyms: Hereditary
Deafness-Retinitis Pigmentosa,
Retinitis Pigmentosa and Congenital Deafness)
What is Usher Syndrome?
Usher syndrome (US) is the most common condition that
involves both hearing and vision problems. A syndrome
is a disease or disorder that has more than one feature
or symptom. The major symptoms of US are hearing impairment
and an eye disorder called retinitis pigmentosa, in
which vision worsens over time. Some people with US
also have balance problems. There are three different
types of US. Although it was first described by Albrecht
Von Graefe in 1858, US was named for Charles Usher,
a British eye doctor, who believed that this condition
was inherited or passed from parents to their children.
Who is affected by
Usher syndrome?
More than half of the estimated 16,000 deaf-blind people
in the United States are believed to have US.
What causes Usher syndrome?
US is inherited or passed from parents to their children
through genes. Genes are located in every cell of the
body and contain the instructions that tell cells what
to do. Some genes specify traits such as hair color.
Other genes are involved in the development of body
parts, such as the ear. Still others determine how parts
of the body work. Each person inherits two copies of
each gene; one gene comes from each parent. Sometimes
genes are altered or mutated. Mutated genes may cause
cells to act differently than expected.
US is passed along in families by autosomal recessive
inheritance, which requires two copies of the US gene
before the disorder is seen. Each parent of a child
with US usually has one standard and one mutated US
gene. A child with US receives two mutated genes, one
from each parent. Usually parents are unaware that they
have or carry a US gene. This is because they would
need two of the mutated genes in order to have signs
of US. Presently, at least eight different genes are
thought to cause the various types of US.
What are the types
of Usher syndrome?
The three types of US are called US
type 1 (US1), US type 2 (US2), and US type 3 (US3).
US1 and US2 are the most common types of US. Together,
US1 and US2 account for approximately 10 percent of
all cases of children who are born deaf.
What are the characteristics
of the three types of Usher syndrome?
People with US1 are profoundly deaf from birth and have
severe balance problems. Many of these individuals obtain
little or no benefit from hearing aids. Most use sign
language as their primary means of communication. Because
of the balance problems, children with US1 are slow
to sit without support and rarely learn to walk before
they are 18 months old. These children usually begin
to develop vision problems by the time they are ten.
Visual problems most often begin with difficulty seeing
at night, but tend to progress rapidly until the individual
is completely blind.
Those with US2 are born with moderate to severe hearing
impairment and normal balance. Although the severity
of hearing impairment varies, most of these children
perform well in regular classrooms and can benefit from
hearing aids. These children most commonly use speech
to communicate. Retinitis pigmentosa, which is a degeneration
of the retina or the part of the eye that receives images
of objects, is characterized by blind spots that begin
to appear shortly after the teenage years. The visual
problems in US2 tend to progress more slowly than the
visual problems in US1. When an individual's vision
deteriorates to blindness, his or her ability to read
speech from the lips is lost.
Children born with US3 have normal hearing and normal
to near-normal balance. Hearing worsens over time. Children
develop noticeable hearing problems by their teenage
years and usually become deaf by mid to late adulthood.
Retinitis pigmentosa in the form of night blindness
usually begins sometime during puberty. Blind spots
appear by the late teenage years to early adulthood.
By mid adulthood, the individual is usually blind.
How is Usher syndrome
diagnosed?
Hearing loss and retinitis pigmentosa
are rarely found in combination. Therefore, most people
who have retinitis pigmentosa and hearing loss probably
have US1 or US2. Special tests such as electronystagmography
(ENG) to detect balance problems and electroretinography
(ERG) to detect retinitis pigmentosa help doctors to
detect US early. Early diagnosis is important in order
to begin special educational training programs to help
the individual deal with the combined hearing and vision
difficulties.
How is Usher syndrome
treated?
Presently, there is no cure for US.
The best treatment involves early identification in
order to begin educational programs. The exact nature
of these educational programs will depend on the severity
of the hearing and vision impairments as well as the
age and abilities of the individual. Typically individuals
will benefit from adjustment and career counseling;
access to technology such as hearing aids, assistive
listening devices or cochlear implants; orientation
and mobility training; and communication services and
independent living training that may include Braille
instruction, low vision services, or auditory training.
What research is being
conducted on Usher syndrome?
Research to precisely identify the specific genes involved
in each Usher syndrome type is moving at a rapid pace.
This research will lead to improved genetic counseling
and early diagnosis, and may eventually expand treatment
options. Scientists are also developing mice that have
the same characteristics as humans who have the various
types of US. Mouse models will make it easier to determine
the function of the various genes involved in US. Research
is also being conducted to improve the early identification
of children with the syndrome. When available, this
testing will provide an accurate genetic diagnosis useful
for early detection of the disorder, and for defining
the risks of other family members or future offspring
being affected.
Sources: National Institute on Deafness and Other
Communication Disorders, 2002.
The Foundation Fighting Blindess, 2002.
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