USHER SYNDROME - TYPE I

Usher Syndrome I; Usher Disease; Usher-Hallgren Syndrome; Halgren Disease; RP-Dysacusis Syndrome; Dystropia Retinae Dysacusis Disease; Graefe-Usher Syndrome; Retinitis Pigmentosa Deafness Syndrome

Usher Syndrome Type I is an inherited disease that causes deafness, balance problems, and retinitis pigmentosa, an eye disorder that causes progressive vision loss. There are three types of Usher syndrome, with Type I being the most severe. Usher syndrome is caused by mutations in the CDH23, MYO7A, USH1C, and USH1G genes.

Diagnostic testing: The diagnosis of Usher syndrome is usually determined through hearing, balance, and vision testing. Age-appropriate audiologic testing is used to evaluate hearing loss. Evaluation of the eyes may include visual field tests to measure peripheral vision; electroretinogram (ERG) to measure the electrical response of the eye’s light sensitive cells; and retinal examination to observe the retina and other structures in the back of the eye. An electronystagmogram (ENG) measures involuntary eye movement that may be associated with balance problems.

Physical findings:

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  Progressive degeneration of the retina;

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  Motor delays; and

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  Balance problems on neuromuscular examination.

ICD-9: 362.74

Children with Usher syndrome - Type I are profoundly deaf at birth. Vestibular balance problems generally present by 18 months of age, with difficulties in sitting without support and then delays in walking ability. Vision loss caused by retinitis pigmentosa begins in early childhood, with rapid progression until the child becomes completely blind, usually within the first decade of life.

There is no cure for this condition. Children with this disorder obtain little or no benefit from hearing aids, and are candidates for cochlear implants. Intervention strategies such as Braille instruction, low vision services or auditory training can help to improve the child’s quality of life.

SUGGESTED PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation:

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  Clinical history and examination that describes the diagnostic features of the impairment;

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  Complete otologic examination and audiometric testing within 2 months of the otologic examination; and

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  Documentation of structural changes to the eye with an evaluation of visual acuity and visual fields.

Suggested Listings for Evaluation:

REMARKS

Most allowances will be based on meeting either the Hearing or Vision loss listings; although molecular genetic testing results may be included in the medical information, obtaining this genetic testing is not necessarily required for adjudication.