Hearing Loss Panel -- Tier II
Download a Test Requisition Form
You can download the Hearing Loss Test Requisition form (69k) in portable document format (.pdf).
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Genes Tested | About the Disorder | Rationale for Testing | Indications | Specimen l Testing Methodology l Sensitivity l Turnaround Time l Cost l CPT Codes l Shipping l Results l Contact Us
Genes Tested
- OTOFERLIN (OTOF)
- MYOSIN 7A (MYO7A)
- CADHERIN (CDH23)
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About the Disorder
Hereditary hearing loss affects about 1 in 1500 infants and accounts for more than 50% of the causes of childhood deafness. Mutations in many different genes result in hereditary hearing loss. These genes may be inherited in an autosomal dominant, autosomal recessive, X-linked, or mitochondrial manner.
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Rationale for Testing
Identification of the specific cause of a child's hearing loss is an important part of a comprehensive hearing loss evaluation. Identification of a specific genetic mutation provides important information about long-term prognosis and medical management. It also provides very specific information on which to base genetic counseling for parents and other at-risk family members. Finally, identification of a genetic mutation, early in the evaluation process, may eliminate the need for further, more invasive and costly medical procedures and tests.
Tier II testing is indicated for patients with sensorineural hearing loss (SNHL) of unknown etiology who have had normal GJB2 (connexin 26) or Tier I test results previously. Tier II testing identifies three less common genetic causes of childhood SNHL and includes testing for mutations in the otoferlin (OTOF), cadherin (CDH23) and myosin 7A (MYO7A) genes. Mutations in CDH23 and MYO7A account for approximately 70% of the mutations which cause Usher syndrome type I. Usher syndrome type I is associated with severe to profound congenital sensorineural hearing loss and retinitis pigmentosa with onset in childhood. Mutations in both of these genes may also be associated with nonsyndromic hearing loss. Mutations in OTOF are associated with auditory neuropathy in some patients and nonsyndromic hearing loss in other patients.
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Indication
SNHL of unknown etiology and with normal GJB2 (connexin 26) or Tier I results previously.
Note: Children with enlarged vestibular aqueduct(s) may benefit for molecular testing for mutations in the SLC26A4 gene for Pendred syndrome prior to Tier II testing.
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Specimen
At least 5 mls whole blood in purple top (EDTA) tube. Alternately, six cyto brushes (cheek swabs) may be collected. (Please call 1-513-636-4474 for a free cyto brush collection kit). Label each brush with patient's name, birth date and date of collection.
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Testing Methodology
PCR and bidirectional sequence analysis of the coding regions and exon/intron boundaries of the OTOF, MYO7A and CDH23 genes.
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Test Sensitivity and Specificity
Overall, approximately 10-15% of the genetic causes of hearing loss can be identified through our Tier II hearing loss panel. Mutations in the OTOF, MYO7A and CDH23 genes account for approximately 5% each of all congenital SNHL in our Midwestern U.S. population. The sensitivity of DNA sequencing is over 99% for the detection of nucleotide base changes, small deletions and insertions in the regions analyzed. Multiple exon deletions and insertions may not be identified by this methodology.
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Turnaround Time
2 months
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Cost
Please call 866-450-4198 for current pricing, discounts and insurance preauthorization.
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CPT Codes
83890x2, 83898(x162), 83894(x162), 83891(x1624), 83904(x324), 83912
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Shipping Instructions
Please enclose test requisition and audiogram with sample. All information must be completed before sample can be processed. Place samples in styrofoam mailer and ship at room temperature by overnight Federal Express to arrive Monday through Friday.
Ship to
Cytogenetics and Molecular Genetics Laboratories
3333 Burnet Avenue NRB 1042
Cincinnati, OH 45229
513-636-4474
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Results
Each Tier II hearing loss panel test report includes a detailed interpretation of the genetic findings, the clinical significance of the result, and specific recommendations for clinical management and additional testing, if warranted. Results will be reported to the referring physician or health care provider as specified on the test requisition form.
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Contact Us
For additional inquiries, contact us:
Phone 513-636-4474
Fax 513-636-4373
Email moleculargenetics@cchmc.org
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