Diagnostic testing or carrier screening for GJB2-related nonsyndromic hearing loss (NHSL). May be used as first-tier genetic test for individuals with NSHL.
- 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: Nonsyndromic hearing loss; recessive mutations typically cause congenital deafness while dominant mutations have variable expressivity.
Incidence: Approximately 1:6500.
Inheritance: Autosomal recessive or dominant depending on specific GJB2 mutation.
Cause: GJB2 gene mutations.
Clinical Sensitivity: 95 percent of GJB2 mutations.
Methodology: Bidirectional sequencing of the entire coding region, exon/intron boundaries, and 5'-UTR of the GJB2 gene sequenced.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Large GJB2 gene deletions or deep intronic mutations will not be identified; hearing loss caused by other genetic or environmental causes will not be detected.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0051375||Connexin 26, Full Gene Sequencing||35300-3|
- Connexin 26 hearing loss
- GJB2 hearing loss
- Hearing Loss, Nonsyndromic