GJB6-RELATED DFNB1 HEREDITARY HEARING LOSS
DNA ANALYSIS
Also see: 6019 - Connexin 26/GJB2 Related Hereditary Hearing Loss

Hereditary hearing loss (HHL) is caused by mutations in different genes, and can be inherited as an autosomal dominant, autosomal recessive, X-linked, or mitochondrial condition. Mutations in the GJB6 gene, which encodes the connexin 30 protein, are associated with autosomal dominant and recessive forms of nonsyndromic hereditary hearing loss (NSHHL). Connexin-30 is thought to play an important role in potassium homeostasis of the inner ear, along with connexin-26 (encoded by the GJB2 gene). Together, GJB6 and GJB2 constitute the autosomal recessive NSHL locus DFNB1. Biallelic mutations in GJB6, biallelic mutations in GJB2, or heterozygous mutations in both GJB6 and GJB2 are responsible for DFNB1-based hearing loss. To date, there are two different GJB6 deletion mutations, spanning 232 or 309 kb that have been associated with DFNB1-based hearing loss. Diagnostic testing for the GJB6 deletion mutations is available to hearing-impaired patients in whom a genetic etiology of hearing loss is suspected or in which a single GJB2 mutation has previously been identified.

Reasons for Referral:

Confirmation of diagnosis of hereditary hearing loss
Carrier detection in family members at risk for a known GJB6 mutation

Testing Methodology:

PCR primers were designed to amplify across the 232 kb and 309 kb GJB6 deletion regions; amplification occurs only when a deletion is present. The assay is performed as one multiplex reaction with co-amplification of GJB6 exon 1 as an internal control.

Sensitivity:

>99% Detection

Specimen Requirements:

Postnatal analysis: 14 ml of blood in EDTA (purple top) tube. Requisition form must accompany the specimen. Prior to any genetic testing, we recommend genetic counseling and we request that the subject sign our consent statement and submit it with the sample. To receive forms, additional information or specimen collection kits, please contact the laboratory.

Turnaround Time:

2 weeks

References:

1. del Castillo I, Villamar M, Moreno-Pelayo MA, del Castillo FJ, Alvarez A, Telleria D, Menendez I, and Moreno F. A deletion involving the connexin 30 gene in nonsyndromic hearing impairment. N Engl J Med (2002); 346(4):243-249.
2. del Castillo FJ, Rodriguez-Ballesteros M, Alvarez A, Hutchin T, Leonardi E, de Oliveira CA, Azaiez H, Brownstein Z, Avenarius MR, Marlin S, Pandya A, Shahin H, Siemering KR, Weil D, Wuyts W, Aguirre LA, Martin Y, Moreno-Pelayo MA, Villamar M, Avraham KB, Dahl HHM, Kanaan M, Nance WE, Petit C, Smith RJH, Van Camp G, Sartorato EL, Murgia A, Moreno F, del Castillo I. A novel deletion involving the connexin-30 gene, del(GJB6-d13s1854), found in trans with mutations in the GJB2 gene (connexin-26) in subjects with DFNB1 non-syndromic hearing impairment. J Med Genet 2005; 42:588-594.

CPT Codes and Prices:

83891, 83894, 83900, 83901, 83912

Shipping Information

Forms:

>> DNA Requisition

Test Codes:

6355