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Usher Syndrome Type II.

Authors

Lentz J1, Keats B2.

Source

GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2019.
1999 Dec 10 [updated 2016 Jul 21].

Author information

1
Neuroscience Center of Excellence, Louisiana State University Health, Sciences Center, New Orleans, Louisiana
2
Emeritus Professor, Department of Genetics, Louisiana State University Health, Sciences Center, New Orleans, Louisiana

Excerpt

CLINICAL CHARACTERISTICS:

Usher syndrome type II is characterized by: Congenital, bilateral sensorineural hearing loss that is mild to moderate in the low frequencies and severe to profound in the higher frequencies; Intact vestibular responses; and Retinitis pigmentosa (RP). RP is progressive, bilateral, symmetric retinal degeneration that begins with night blindness and constricted visual fields (tunnel vision) and eventually includes decreased central visual acuity; the rate and degree of vision loss vary within and among families.

DIAGNOSIS/TESTING:

The diagnosis of Usher syndrome type II is established in a proband using electrophysiologic and subjective tests of hearing and retinal function. Identification of biallelic pathogenic variants in one of three genes – ADGRV1, WHRN (DFNB31), and USH2A – establishes the diagnosis if clinical features are inconclusive.

MANAGEMENT:

Treatment of manifestations: Early fitting of hearing aids and speech training. Surveillance: Routine auditory evaluation to detect changes that may require modifications to hearing aids; routine ophthalmologic evaluation to detect potentially treatable complications such as cataracts. Agents/circumstances to avoid: Tunnel vision and night blindness can increase the likelihood of accidental injury. Competition in sports requiring a full range of vision may be difficult and possibly dangerous. Progressive loss of peripheral vision impairs the ability to safely drive a car. Evaluation of relatives at risk: The hearing of at-risk sibs should be assessed as soon after birth as possible to allow early diagnosis and treatment of hearing loss.

GENETIC COUNSELING:

Usher syndrome type II is inherited in an autosomal recessive manner. Each subsequent pregnancy of a couple who has had a child with Usher syndrome type II has a 25% chance of resulting in an affected child, a 50% chance of resulting in an unaffected child who is a carrier, and a 25% chance of resulting in an unaffected child who is not a carrier. Prenatal testing is possible for pregnancies at increased risk if the pathogenic variants have been identified in the family.

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