Test Overview
Test Methodology

GJB2 (exonic and intronic splice site consensus) sequences are amplified using specific primers, and bidirectionally sequenced using a fluorescent method. The 2 most frequent large deletions in GJB6 are detected by a PCR-based method.

Test Usage

Confirmation of a diagnosis of hearing loss with a genetic etiology or carrier testing in families with a known GJB2 mutation. Connexin tesing will be performed as a sequential reflexive assay consisting of Connexin 26 (GJB2) Mutation Analysis and Connexin 30 (GJB6) Deletion Analysis. A patient with non-syndromic hearing loss can have two mutations in Connexin 26, two mutations in Connexin 30, or one mutation in Connexin 26 and one mutation in Connexin 30. Mutations in the GJB2 (Connexin 26) gene account for 30-70% of non-syndromic recessive (and a small number of autosomal dominant) deafness in Caucasian populations. Approximately 40% of individuals with sporadic non-syndromic hearing loss also carry GJB2 mutations.

Reference Range *

Interpretive report provided.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

This assay will not detect large deletions in the GJB2 gene or intronic mutations outside the region sequenced in the GJB2 gene. Point mutations and small nucleotide level deletions in GJB6 cannot be detected by the PCR-based deletion assay used here. Mutations in other genes associated with hearing loss will not be identified by this testing.

Test Details
Days Set Up
Monday - Friday
Analytic Time

14 - 21 days

Soft Order Code
CX26S
MiChart Code
Connexin 26 (GJB2) Gene Sequencing
Synonyms
  • GJB2 Mutation Detection
  • GJB2 Sequencing
  • Connexin 26 Sequencing
  • Hearing Loss Panel
  • Connexin 30 (GJB6) Deletion Analysis
  • GJB6 346kb Deletion
  • GJB2 35delG Mutation
  • Connexin 30 (GJB6) Deletion Analysis
Laboratory
MMGL
Section
MMGL Molecular Genetics
Specimen Requirements
Collection Instructions

Collect blood specimen in a EDTA lavender top tube. Send it within 24 hours if stored at room temperature or within 5 days if stored refrigerated.

Fill out a MLabs Molecular test requisition (or place an e-order if applicable):
https://mlabs.umich.edu/media/166
Fill out a Clinical History Form for Insurance Prior Authorization (include all required documentation indicated at the bottom of this form):
https://mlabs.umich.edu/sites/default/files/2020-08/file/mlab11618clini…
Fill out a UMHS Request and Consent for Genetic Testing form:
https://mlabs.umich.edu/sites/default/files/2023-04/file/germline-conse…
Michigan State law requires the ordering provider to obtaining informed consent from the patient prior to prognostic or predictive genetic testing. Contact a MLabs Client Services Center at 800-862-7284 to request paper copies or to setup a client account.

Alternate Specimen
Cheek swab kit (Oragene OCD-100), follow collection instructions.
Saliva kit (Oragene OGD-510), follow collection instructions.
Normal Volume
5 mL whole blood
Minimum Volume
1 mL whole blood (0.5 mL infants)
Storage Temperature
Room temperature up to 24 hours or 2-8°C up to 5 days for blood
2-36°C for saliva
Rejection Criteria
Hemolyzed blood sample. Fresh tissue (POC) or paraffin embedded specimens are not acceptable.
Additional Information

Testing will begin with Connexin 26 (GJB2) mutation analysis, and will be followed by Connexin 30 (GJB6) deletion analysis at an additional charge if zero (0) or one (1) pathogenic mutation is found in the GJB2 gene. By ordering this test the clinician acknowledges that additional reflex testing will be performed and billed at a separate additional charge if indicated. Connexin 30 (GJB6) deletion analysis may also be ordered individually (order code CX30DS). By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes medical geneticist interpretation of results billed as a separate additional charge. This test is not available without interpretation.

Billing
CPT Code
CX26SS: 81252; CX30DS: 81254
Fee Code
CX26SS: DA010; CX30DS: DA013
Pro Fee CPT
G0452-26
NY State Approved
No