Usher Syndrome


Test Details
TEST CODE NGS402
TEST METHODOLOGY NGS
TAT (TURNAROUND TIME) 2 - 4 weeks
GENES 12
CPT CODE 81404, 81407 x2, 81408 x2
PRICE $1795
RECOMMENDED MNG KITS
  • SINGLE Blood Genetic Testing
  • Buccal Swab Genetic Testing

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Clinical Information
Clinical Significance

Usher syndrome is an autosomal recessive condition characterized by partial or total hearing loss, and vision loss that worsens over time. The hearing loss is classified as sensorineural, meaning that it is caused by abnormalities of the inner ear. The loss of vision is caused by retinitis pigmentosa (RP), a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina. Night vision loss begins first, followed by blind spots that develop in the peripheral vision. Over time, these blind spots enlarge and lead to ‘tunnel vision.’ In some cases, vision is further impaired by cataracts. However, many people with RP retain some central vision throughout their lives. The most common forms of Usher syndrome are types I, II, and III.

Most individuals with Usher syndrome type I are born with severe to profound hearing loss. Unless fitted with a cochlear implant, affected children do not typically develop speech. Progressive vision loss caused by RP becomes apparent in childhood.

Usher syndrome type II is characterized by hearing loss from birth and progressive vision loss caused by RP that begins in adolescence or adulthood. The hearing loss associated with this form of Usher syndrome ranges from mild to severe and mainly affects the ability to hear high-frequency sounds. The degree of hearing loss varies within and among families with this condition, and it may become more severe over time.

Those with Usher syndrome type III experience hearing loss and vision loss beginning somewhat later in life. Unlike the other forms of Usher syndrome, type III is usually associated with normal hearing at birth. Hearing loss typically begins during late childhood or adolescence, after the development of speech, and becomes more severe over time. By middle age, most affected individuals have profound hearing loss. Vision loss caused by RP also develops in late childhood or adolescence.

Relevant Diseases
  • Usher Syndrome

Specimen Information
Acceptable Sample Types
  • Muscle
  • Cultured Fibroblasts
  • Whole Blood - EDTA
  • Extracted DNA - Leukocytes
  • Buccal Cells
Sample Preparation: (1) Blood specimens: Draw blood in an EDTA tube. Preferred volume: 4 milliliters (adults and pediatrics), Minimum volume: 2 milliliters; (2) DNA extracted from leukocytes, muscle, or fibroblasts: Preferred quantity: 4 micrograms, Minimum quantity: 3 micrograms (Genomic DNA should be eluted in sterile Dnase/Rnase free water or TE. The A260:A280 ratio should be 1.8-2.0.); (3) 2 T-25 flasks of fibroblasts; (4) 50-75 milligrams muscle snap frozen in liquid nitrogen and maintained at -80°Celsius or below. (5) Skin biopsy (Fibroblasts will be cultured from skin specimen for genetic testing): Skin biopsy may be taken from the inner forearm with a sterile skin punch (2-5 millimeters) or at incision site of muscle biopsy. Site is sterilized with alcohol swabs only (other reagents will inhibit cell isolation/growth). Biopsy site may be anaesthetized with 2% lidocaine with epinephrine. Depth of punch is 2mm. Transfer skin biopsy into 15 milliliter conical tube filled with sterile culture media. (6) Buccal cells.
Shipping Condition: MNG SmartKits are available for free shipping of specimens. Please see our website for details. If you are not using a MNG SmartKit: (1) Blood specimens should be shipped in a secure container at room temperature. (2) Extracted DNA should be shipped priority overnight at ambient temperature. (3) T-25 flasks containing fibroblasts should be shipped in an insulated container at room temperature. Flasks should be completely filled with media and cells should be ~90% confluent. Fibroblast samples must be certified free from Mycoplasma. MNG is able to perform this service for a small charge (See TC05). (4) Muscle samples should be shipped frozen in an insulated container with 5-7 lbs dry ice. (5) Buccal cells should be shipped in a secure container at room temperature. (6) Skin Biopsy: Conical containing the skin specimen should be shipped in a secure container with cold pack (DO NOT FREEZE). All samples should be shipped overnight at the proper temperature for receipt by our lab Monday thru Saturday (No Sunday or holiday deliveries accepted).

Genes Assessed
CDH23
CIB2
CLRN1
DFNB31
GPR98
HARS
MYO7A
PCDH15
PDZD7
USH1C
USH1G
USH2A

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