Laboratory Test Information Guide

Details for Non-Syndromic Recessive Deafness

Test Name: Non-Syndromic Recessive Deafness
Alternate Name(s): RD
Laboratory: Molecular Diagnostics
Specimen Type: Whole blood-2 x 4 mL Lavender EDTA top Vacutainer tube
Collection Information: Blood samples must be maintained at room temperature.
Test Schedule: As Required
Monday - Friday
0800 - 1600 h
Turnaround time from when specimen
is received in testing laboratory:
6 weeks
Reference Range: See report
Effective Date:  
Revised Date: 2016-03-21
Critical Value: N/A
Interpretive Comments: Severe deafness or hearing impairment is the most prevalent inherited sensory disorder, affecting about 1 in 1,000 children. Most deafness results from peripheral auditory defects that occur as a consequence of either conductive (outer or middle ear) or sensorineuronal (cochlea) abnormalities. Although a number of mutant genes have been identified that are responsible for syndromic (multiple phenotypic disease) deafness such as Waardenburg syndrome and Usher 1B syndrome, little is known about the genetic basis of non-syndromic (single phenotypic disease) deafness1. Mutations in the connexin 26 (Cx26) gene, which codes for a gap junction protein (GJB2), are associated with the type of autosomal recessive nonsyndromic neurosensory deafness known as "DFNB1." Studies2 indicate that DFNB1 (13q11-12) causes 20% of all childhood deafness and may have a carrier rate as high as 2.8%. Analysis of the Cx26 gene may be effected by direct sequence analysis (both sense and antisense) of three overlapping fragments of PCR-amplified genomic DNA.


1. Kelsell DP, et al. Nature 1997 387:80-3
2. Kelley PM, et al. Am J Hum Genet (1998) 62(4):792-9
Special Processing:  
Comments: For more information click on:
Molecular Diagnostic Laboratory
Method of Analysis: DNA Sequence Analysis
Critical Information Required: Pedigree required
Storage & Shipment: Must be received within 5 days of collection, shipped at room temperature by courier/overnight delivery.
System Codes: 
Referred To:  

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