Diagnostic testing for GJB6-related nonsyndromic hearing loss. Carrier screening for GJB6-related nonsyndromic hearing loss.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
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.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2001957||Connexin 30 GJB6 Deletion 309|
|2001958||GJB6 DEL Specimen Type|
|2001959||Connexin 30 Interpretation|
|2002107||Connexin 30 GJB6 Deletion 232|
- Connexin 30 mutation assay
- GJB6 deletions assay