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.
Polymerase Chain Reaction/Capillary Electrophoresis
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Background Information for Hearing Loss, Nonsyndromic, Connexin 30 (GJB6) 2 Deletions:
Characteristics: Moderate to profound nonsyndromic hearing loss (NSHL).
Incidence: Approximately 1 in 30 individuals with NSHL has a GJB6 deletion; 1 in 100,000 in the general population.
Inheritance: Autosomal recessive. Compound heterozygotes for GJB2 and GJB6 mutations are affected. Twenty percent of GJB2 heterozygotes with NSHL have a GJB6 deletion; homozygosity for GJB6 deletions is rare.
Cause: GJB6 gene mutations.
Mutations Tested: 309kb del(GJB6-D13S1830), previously reported as 342kb, and 232kb del(GJB6-D13S1854).
Clinical Sensitivity: Dependent on ethnicity.
Clinical Specificity: 99 percent.
Methodology: Multiplex PCR using deletion-specific primers, followed by capillary gel electrophoresis.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: GJB6 mutations other than the two targeted 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.
Laboratory Developed Test (LDT)
|Component Test Code*||Component Chart Name||LOINC|
|2001957||Connexin 30 GJB6 Deletion 309|
|2001958||GJB6 DEL Specimen Type||31208-2|
|2001959||Connexin 30 Interpretation||50398-7|
|2002107||Connexin 30 GJB6 Deletion 232||41100-9|
- Connexin 30 mutation assay
- GJB6 deletions assay