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
MiChart Code
Connexin 26 (GJB2) Gene Sequencing
  • Generic Peds Genetics Test
  • CS26S
  • GJB2 Mutation Detection
  • GJB2 Sequencing
  • Connexin 26 Sequencing
  • Connexin 26 Inv+Seq Shadow
  • CX26SS
  • Hearing Loss Panel
  • CX30D
  • Connexin 30 (GJB6) Deletion Analysis
  • GJB6 346kb Deletion
  • GJB2 35delG Mutation
  • CX30DS
  • Connexin 30 deletion Shadow
  • Connexin 30 (GJB6) Deletion Analysis
MMGL Molecular Genetics
Specimen Requirements
Collection Instructions

Collect specimen in a lavender top tube. Send intact specimen within 24 hours if stored at room temperature or within 5 days if stored refrigerated. Include the patient's family history, pedigree, and ethnicity on the test requisition. Obtaining informed consent from the patient prior to genetic testing is strongly recommended. If desired, a UMHS Request and Consent for Genetic Testing form can be obtained from the MMGL Molecular Genetics Laboratory by contacting the MLabs Client Services Center at 800-862-7284 or online at https://mlabs.umich.edu/media/188.

Normal Volume
5 - 10 mL EDTA whole blood
Minimum Volume
2 mL EDTA whole blood
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.

CPT Code
CX26SS: 81252; CX30DS: 81254
Fee Code
CX26SS: DA010; CX30DS: DA013
Pro Fee CPT