GJB2 Sequencing, Family-targeted (Single Exon Sequencing−Known Mutation)

CPT: 81253
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Test Details

Synonyms

  • Connexin 26
  • Hearing Loss (GJB2)

Test Includes

This test only covers the exon or amplicon that harbors the variant(s) of interest. Other regions of the gene will not be examined.

Use

Detects known familial mutations in the connexin 26 (GJB2) gene associated with nonsyndromic sensorineural hearing loss (NSHL). This option is available when the mutation is known and can be documented by the ordering physician. If the mutation cannot be documented, please order full gene sequencing.

Limitations

This method does not reliably detect mosaic variants; large deletions; large duplications, inversions, or other rearrangements; deep intronic variants or variants outside of the regions targeted by this analysis. It may be affected by allele-dropout, it may not allow determination of the exact numbers of T/A or microsatellite repeats, and it does not allow any conclusion as to whether two heterozygous variants are present on the same or on different chromosome copies.

Methodology

DNA sequencing

Additional Information

Connexin 26 is one of the most significant genes involved in congenital, nonsyndromic, sensorineural hearing loss (NSHL, OMIM 220920) (GJB2, OMIM 121011). Connexin 26 produces a protein that directs the intracellular transfer of ions and molecules that are important in hearing. GJB2 is associated with both autosomal recessive (DFNB1) and autosomal dominant (DFNA3) hearing loss.

Specimen Requirements

Specimen

Whole blood, buccal swab, amniotic fluid, or chorionic villus sample (CVS) (Submission of maternal blood is required for fetal testing.)

Volume

7 mL whole blood, 4 buccal swabs, 10 mL amniotic fluid, or 20 mg CVS

Minimum Volume

3 mL whole blood, 2 buccal swabs, 5 mL amniotic fluid, or 10 mg CVS

Container

Lavender-top (EDTA) tube or yellow-top (ACD) tube; sterile plastic conical tube, two confluent T-25 flasks for fetal testing or LabCorp buccal swab kit

Storage Instructions

Maintain specimen at room temperature or refrigerate at 4°C.

Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; wet buccal swab

Clinical Information

References

Dong J, Katz DR, Eng CM, Kornreich R, Desnick RJ. Nonradioactive detection of the common connexin 26 167delT and 35delG mutations and frequencies among Ashkenazi Jews. Mol Genet Metab. 2001 Jun; 73(2):160-163.11386851
Milunsky JM, Maher TA, Yosunkaya E, Vohr BR. Connexin-26 gene analysis in hearing-impaired newborns. Genet Test. 2000; 4(4):345-349.11216657
Scott DA, Kraft ML, Carmi R, et al. Identification of mutations in the connexin 26 gene that cause autosomal recessive nonsyndromic hearing loss. Hum Mutat. 1998; 11(5):387-394.9600457
Smith RJH, Van Camp G. Nonsyndromic hearing loss and deafness, DFNB1. GeneReviews. 2008 Sep 28 (updated 2011 Jul 14). Available at http://www.ncbi.nlm.nih.gov/books/NBK1272. Accessed September 10, 2009.20301449
Sobe T, Vreugde S, Shahin H, et al. The prevalence and expression of inherited connexin 26 mutations associated with nonsyndromic hearing loss in the Israeli population. Hum Genet. 2000; 106(1):50-57.10982182

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
511414 GJB2 Family Targeted 35300-3 511415 GJB2 Family Targeted 35300-3

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The LOINC® codes are copyright © 1994-2017, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf