Ordering Recommendation

Diagnostic test for individuals with nonsyndromic hearing loss and 1 identified GJB2 variant. Carrier screening if family history of GJB6 deletion or for reproductive partner of individual with GJB6 or GJB2 variants.

Mnemonic

GJB6 DEL

Methodology

Polymerase Chain Reaction/Capillary Electrophoresis

Performed

Varies

Reported

7-10 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature

Refrigerated. Also acceptable: Room temperature

Unacceptable Conditions
Remarks
Stability

Ambient: 1 week; Refrigerated: 1 month; Frozen: Unacceptable

Reference Interval

Interpretive Data

Background:  Hearing Loss, Nonsyndromic, Connexin 30 (GJB6) 2 Deletions:
Characteristics
: Moderate to profound nonsyndromic hearing loss (NSHL). Large GJB6 gene deletions involving cis-regulatory elements for GJB2 (connexin 26) result in the loss of expression of GJB2. Thus, compound heterozygosity for a pathogenic GJB2 variant and GJB6 large deletion results in NSHL.
Incidence
: Approximately 1 in 30 individuals with NSHL has a GJB6 deletion; 1 in 100,000 in the general population. Twenty percent of GJB2 heterozygotes with nonsyndromic hearing loss have a GJB6 deletion; homozygosity for GJB6 deletions is rare.
Inheritance
: Autosomal recessive.
Cause
: Pathogenic germline variants in GJB6.
Variants Tested
: 309kb del(GJB6-D13S1830, also known as 342kb) and 232kb del(GJB6-D13S1854).
Clinical Sensitivity
: Dependent on ethnicity.
Methodology
: Multiplex PCR using deletion-specific primers, followed by capillary gel electrophoresis.
Analytical Sensitivity and Specificity
: Greater than 99 percent.
Limitations
: GJB6 variants other than the two targeted deletions will not be identified. The etiology of hearing loss due to other genetic or environmental causes will not be determined. Diagnostic errors can occur due to rare sequence variations. Interpretation of this test result may be impacted if this patient has had an allogeneic stem cell transplantation.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Compliance Category

Laboratory Developed Test (LDT)

Note

Hotline History

N/A

CPT Codes

81254

Components

Component Test Code* Component Chart Name LOINC
2001957 Connexin 30 GJB6 Deletion 309 34504-1
2001958 GJB6 DEL Specimen Type 31208-2
2001959 Connexin 30 Interpretation 50398-7
2002107 Connexin 30 GJB6 Deletion 232 41100-9
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • Connexin 30 mutation assay
  • GJB6
  • GJB6 deletions assay
Hearing Loss, Nonsyndromic, Connexin 30 (GJB6) 2 Deletions