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Test Code CX 26 KNOWN Connexin 26 Known Mutation

Clinical System Name

Connexin 26 Known Mutation





Targeted analysis for variants previously identified through clinical testing of a family member or  research testing of the individual.  For full gene sequencing please see Connexin 26/30: sequencing of Connexin 26 reflex to Connexin 30 deletion testing.



Sample Requirements

Specimen: Whole blood, cord blood

Container(s): Lavender/EDTA, Yellow/ACD A or B

Preferred Vol: 3 mL

Minimum Vol: 1 mL


Note: Heparin samples (Green tops) are unacceptable.


Specimen: Extracted DNA

Minimum: 10µg

Note: DNA concentration minimum 50 µg/mL; 260/280 ratio 1.70-2.00


Specimen: Cultured cells

Acceptable:  Fibroblasts

Container(s): T-25 flasks

Preferred Vol: 2 flasks

Processing Instructions

Reject due to: Heparin

Spin: No

Aliquot: No

Temp: Refrigerate

Storage location: Molecular Genetics box in CPA refrigerator #2


Off-site collection: Refrigerate blood samples until ready to ship.  Transport all sample types at room temperature via overnight shipping.


Specimen Type Temperature Time
Cultured cells Room temp 3 days
Whole blood, extracted DNA Room temp 3-5 days
Whole blood, extracted DNA Refrigerated 7 days
Extracted DNA Frozen ok


Note: Whole blood samples > 7days may be submitted to be assessed by our lab for acceptability for testing.


STAT Performed TAT
Contact lab Monday - Friday 2-3 weeks


Performing Laboratory

Seattle Children's Laboratory


Department:  Molecular Genetics Laboratory

Phone: 206-987-3872


Lab Client Services: 206-987-2617


Lab Genetic Counselors:

Reference Range

Interpretive report will be provided


Method: PCR + Sequencing


Limitations: This test is for targeted variant analysis only.  Variants must be known.

CPT Codes

81253 (updated 2/2/16 by jconta)

Special Instructions

Please provide copies of proband reports when requesting known variant analysis for cases NOT performed by Seattle Children's Lab.


Links to: GeneReviews: Nonsyndromic Hearing Loss and Deafness, DFNB1


Molecular Genetics

Clinical Utility

Targeted variant analysis for the Gap Junction Beta-2 Protein GJB2 gene (connexin 26) associated with nonsyndromic hearing loss and deafness (DFNB1).  DFNB1 is characterized by congential non-progressive, mild-to-profound sensorineural hearing impairment.   DFNB1 is inherited in an autosomal recessive or possibly digenic manner.