GJB2 and GJB6 Related Disorders
Clinical Characteristics
DFNB1
- Sensorineural hearing loss:
- Typically congenital
- Usually nonprogressive
- Mild to profound
- No associated medical findings
DFNA3
- Sensorineural hearing loss:
- Typical onset in childhood
- Usually progressive
- Moderate to severe
- High frequencies more severely affected
- No associated medical findings
Allelic Dermatologic Conditions
- GJB2:
- Palmoplantar keratoderma with deafness
- Keratitis-ichthyosis-deafness (KID) syndrome
- Hystrix-like ichthyosis-deafness (HID) syndrome
- Vohwinkel syndrome (deafness, keratopachydermia, constrictions of fingers and toes)
- Bart-Pumphrey syndrome (knuckle pads, leukonychia, deafness)
- GJB6:
- Hidrotic ectodermal dysplasia 2 (Clouston syndrome)
Inheritance pattern:
- Autosomal recessive for DFNB1
- Autosomal dominant for DFNA3 and allelic dermatologic conditions
What Can Be Learned From This Test
Testing is performed by sequencing untranslated exon 1, coding exon 2, and the surrounding intronic regions of GJB2. This will detect point mutations, small deletions and small insertions. It will not detect a partial or whole gene deletion or duplication. GJB6 is analyzed for the common 309 kb deletion, and coding exon 3 is sequenced.
A negative test result does not rule out a genetic cause of sensorineural hearing loss as there are many other genes associated with this trait. This test will only detect mutations in GJB2 and GJB6.
Sample Requirements
Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).
Turnaround time: 10-14 business days
CPT Codes and Cost
GJB2
- Code: 81252
- Cost: $300
Known Variant Testing
- Code: 81253
- Cost: $225
GJB6
- Code: 81254
- Cost: $300
Known Variant Testing
- Code: 81479
- Cost: $225
Additional Information
- GeneReviews: