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推荐杏吧原创 Usher Syndrome

What is Usher Syndrome?

Usher syndrome is a genetic disorder involving the loss of both sight and hearing. The hearing loss generally occurs at birth or shortly thereafter; while a progressive loss of vision due to retinitis pigmentosa (a degeneration of the retina of the eyes) begins later in life, usually before adolescence. AT first, the vision loss may be gradual and barely noticeable, but in almost all cases the result is legal blindness.

There are currently three identifiable types of Usher syndrome: Usher syndrome Type 1, Usher syndrome Type II and Usher syndrome Type III. An individual with Usher Type I has a profound hearing loss at birth, experiences balance problems due to vestibular loss, and experiences vision loss usually in early childhood. In Usher Type II, an individual has a sloping audiogram going from a moderate loss in the low frequencies to profound impairments in the higher frequencies, has no balance problems, and usually begins to lose his/her vision in the midteens. A person with Usher syndrome Type III starts with normal or near-normal hearing that progressively deteriorates, might have some balance disturbance, and experiences vision loss by midteens.

Usher syndrome occurs in approximately 1 in 25,000 and the incidence is estimated to possibly be as high as 1 in 10,000 individuals. This range is due to the difficulty in identifying persons with Usher syndrome, particularly persons with Type II Usher. Of persons with Usher syndrome, approximately 90% will have Type I Usher, with Type II accounting for almost 10%. At this time, Usher syndrome Type III appears to occur primarily in Finland.

While only approximately 4 in 100,000 people are diagnosed with Usher syndrome, it is estimated that 3 to 6 percent of people who have a hereditary hearing loss have the syndrome. An equal percentage of children who are hard of hearing my also have Usher syndrome.

Why is Early Identification Crucial?

  1. The gradual decrease in vision may be unnoticed by the individual, who may continue activities (such as driving or working in hazardous conditions) that cannot be continued safely. Another safety issue pertains to night blindness, usually the first manifestation of retinitis pigmentosa. A child who is night-blind can be at risk in any area where there is traffic or other dangers.
  2. The individual, parents, and teachers can plan for education, vocational experiences, and career planning, taking into account eventual visual difficulties.
  3. A diagnosis of Usher syndrome allows the family to consider genetic counseling and testing for other children in the family. Usher syndrome runs in families. Some families might choose genetic counseling and testing in order to reduce the risk of having other affected children as well as to reduce the risk of an individual with Usher syndrome having affected children. Other families might choose genetic counseling in order to plan for needed supports.
  4. The family and individual may choose to seek counseling and support to cope with the present and prepare for the future.
  5. Knowing about the visual impairment may influence decisions regarding communication. The individual and family will have the time necessary to gain skills and experience in communication techniques that will enable the person to continue to communicate with others even if a severe visual impairment occurs. For example, it may be easier for a person with Usher syndrome to learn tactile communication as a child rather than as an adult.

Usher Syndrome Screening Forms

Due to accessibility concerns, if you would like screening forms for Usher's Syndrome, please contact MaryAnn Demchak through email. We can provide the following forms:

  • Family Questionnaire
  • Behavioral Observations
  • Visual Field Screening
  • Low-risk Causes
  • Dark Adaptation Screening

Who is at Risk?

The first noticeable symptom of Usher syndrome is a sensorineural hearing loss. If the hearing loss is a result of any of the conditions listed below, the person is at low risk for Usher syndrome. There is always a small chance that Usher syndrome is a secondary cause of the hearing loss, but this is extremely rare.

While the individuals who have a hearing loss due to any of the conditions listed below are at low risk for Usher syndrome, they may suffer a vision loss for other reasons. This makes it especially important to have regular, comprehensive eye exams.

Low Risk Causes: 

  • Conductie loss Rubella (German Measles)
  • Kidney disease
  • Otitis Media
  • Trauma/accident
  • Scarring the the eardrum
  • Genetic deafness*
  • Noise-induced loss
  • Auditory neuritis
  • Oxotoxic drug therapy
  • Diabetes
  • Viral Infection
  • Disease (i.e., Meningitis Mumps, Scarlet Fever, Measles, Chicken Pox, Encephalitis)

*The genes for deafness and for Usher syndrome are different. An individual at risk for Usher syndrome will probably not have another family member who is deaf, unless they too have Usher syndrome.

What are Symptoms the Individual May Notice?

Individuals with Usher syndrome may not notice the subtle changes associated with gradual visual loss. Questions such as those listed below may help the person with Usher syndrome, the family, teacher, or school nurse acquire the information needed for a basic screening.

Ask the Individual:

  • When you walk inside a dark movie theater or room, do you have a hard time seeing seats and people?
  • When you come inside from a bright, sunny day, can you see things and people?
  • Do you trip over things?
  • Does sunlight hurt your eyes?
  • Do you often spill liquids when pouring them into a cup or glass?
  • Can you see stars in the sky at night?
  • If someone waves to you from the side, do you see them when you are not looking at them?
  • Is it hard to find small objects when you drop them on the floor?
  • Do you bump into people, chairs, things?
  • Do you have trouble riding a bicycle?

Acknowledgments

The Usher syndrome web pages were adapted from brochures previously developed by the Indiana Deaf-Blind Services Project, the Alaska Usher Syndrome Screening Project, and Oregon's Usher Syndrome Project.

Additional information was taken from the following articles and resources:

  • Davenport, S.L.H. (1994). Usher syndrome: Vision and hearing loss. Hereditary Deafness Newsletter of America, 4(1), 1-4.
  • Fillman, R.D., Leguire, L.E., Rogers, G.L., Bremer, D.L., & Fellows, R.R. (1987). Screening for vision problems, including Usher's syndrome, among hearing impaired students. American Annals of the Deaf, 132(3), 194-198.
  • Kimberling, W.J., & Moller, C. (1995). Clinical and molecular genetics of Usher syndrome. Journal of the American Academy of Audiology, 6 63-72.
  • Miner, I.D. (1995). Psychological implications of Usher syndrome, Type I, throughout the life cycle. Journal of Visual Impairment and Blindness, 89 287-296.