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Hereditary Non-Syndromic Sensorineural Hearing Loss Test

Genes:
GJB2;
GJB6

Syndrome Information

Clinical Description

Approximately 70% of sensorineural hearing loss is non-syndromic, with 80% of cases following autosomal recessive inheritance and 15-20% of cases following autosomal dominant inheritance. Pathogenic variants in GJB2 and GJB6 have been identified in greater than half of individuals with non-syndromic sensorineural hearing loss.

Inheritance Pattern

Autosomal recessive, autosomal dominant

Test Information

Test Method

Bidirectional sequencing of the coding regions and intron-exon boundaries of GJB2; PCR and fragment sizing for identification of the D13S1830 and DS13S1854 deletions in GJB6

Clinical Utility

Identification of causative variants in cases of hereditary non-syndromic sensorineural hearing loss; assessment of recurrence risk within the family; targeted diagnostic testing of relative of proband with inconclusive clinical presentation; predictive prenatal testing when familial pathogenic variant is known

Clinical Sensitivity

GJB2/GJB6-related hearing loss accounts for 50% of recessive non-syndromic severe to profound hearing loss in the US population (or populations with similar ethnic admixture), but is lower in other ethnic populations (patients of Chinese or Middle Eastern ancestry; Smith and Jones, 2016, PMID 20301449).  When large cohorts of children with failed newborn hearing screen or clinical presentation of hearing loss are considered, without regard to severity, 2 disease-causing GJB2/GJB6 variants will be identified in approximately 5.5% (Schimmenti et al., 2008, PMID 18580690; Schimmenti et al., 2011, PMID 21912263; Svidnicki et al., 2015, PMID 26399936).  At least 1 disease-causing variant will be identified in >95% of affected children.  This test is only validated for inherited gene alterations associated with the phenotype(s) specified above.  

Analytic Sensitivity

Sequencing:  > 97% accuracy for nucleotides evaluated (All nucleotides were evaluated)

Fragment Sizing: >98%; Analysis parameters are not designed to detect mosaicism

Sample Requirements

3-6ml whole blood in EDTA (purple topped) tubes. (see Pediatric or Adult blood sample algorithms for additional information) We prefer whole blood for all tests.

Turn Around Time

4 weeks

Fee and CPT Codes

Fee: $940

CPT: 81252; 81254