Hereditary Hearing Loss Secondary to GJB2 (Connexin 26) Mutations
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About the Disorder | Indications | Specimen l Testing Methodology l Sensitivity l Turnaround Time l Cost l CPT Codes l Shipping l Results l Contact Us
About the Disorder
Hereditary hearing loss affects about 1 in 1500 infants and accounts for more than 50% of causes of childhood deafness. Mutations in many different genes result in hereditary hearing loss and can be inherited in an autosomal dominant, autosomal recessive, X-linked, or mitochondrial manner. Mutations in the GJB2 gene, which encodes for the protein, connexin 26, are the most frequent cause of autosomal recessive nonsyndromic hereditary hearing loss. Mutations in the GJB2 gene are found in various populations, with a carrier rate of approximately 1-in-30 in the United States Caucasian population, and 1-in-20 in the Ashkenazi Jewish population.
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Indications
- Hearing loss of unknown etiology
- Carrier testing in relative of patient with a proven GJB2 mutation
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Specimen
At least 2 mls whole blood in purple top (EDTA) tube. Alternately, two cytobrushes (cheek swabs) may be collected. (Please call 1-513-636-4474 for a free cytobrush collection kit.) Label each tube or brush with patient's name, birth date and date of collection.
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Methodology
PCR-based sequencing of the exon/intron boundaries and the entire coding sequence which is contained within exon 2 of the GJB2 gene.
Analysis of GJB2 is also offered as part of our Comprehensive Hearing Loss Panel and our Hearing Loss Panel - Tier I, both of which include analyses for additional genes that contribute to hereditary hearing loss, in addition to GJB2.
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Test Sensitivity and Specificity
PCR-based sequencing detects 99% of the reported mutations in GJB2. 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. Mutations in GJB2 account for 18% of congenital SNHL in our Midwestern U.S. population.
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Turnaround Time
2-3 weeks
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Cost
Please call 866-450-4198 for current pricing, discounts and insurance preauthorization.
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CPT Codes
83890, 83898(x2), 83894(x2), 83891(x2), 83904(x6), 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 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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