Specimen:

Whole Blood

Collection Medium:

Minimum:

Preferred Minimum:  8 mL whole blood
Absolute Minimum:  4 mL whole blood

Analytic Time:

8 weeks

Reference Range:

None detected

Interpretive Data:

DFNB4 and Pendred syndrome DFNB4
Baldwin and colleagues reported linkage of a family with recessive, 
nonsyndromic deafness to chromosome 7q31 in 1995 and designated this 
locus as DFNB4. Mutations in SLC26A4 are causally related to deafness 
at this locus. Inner ear computed tomography has shown that DFNB4 
includes dilation of the endolymphatic duct (DVA, also called enlarged 
vestibular aqueduct syndrome, EVA).

Pendred Syndrome
Pendred syndrome is a common syndromic form of hearing loss (Fraser 
1965). Clinical features include inner ear abnormalities, sensorineural 
hearing loss and diffuse thyroid enlargement or goiter. Inner ear 
computed tomography has shown that the Pendred Syndrome phenotype 
includes dilation of the endolymphatic duct and sac, enlargement of the 
vestibular aqueduct and cochlear dysplasia. This constellation of 
anomalies is known as Mondini malformation or Mondini dysplasia.

SLC26A4 (encoding Pendrin)
Mutations in SLC26A4 cause Pendred Syndrome. The gene is a member of 
the solute carrier gene family and functions as an anion carrier. It 
has 21 exons and the encoded protein, called Pendrin, has 780 amino 
acids.

Sensitivity is greater than 99%.

Comments:

Please print, complete and submit the Deafness Testing Requisition 
from the Molecular Otolaryngology & Renal Research Laboratory, to 
Specimen Control/Mailouts with the specimen and the Epic Requisition.

Methodology:

Screening for SLC26A4 is performed by DHPLC and sequencing. 
Oligonucleotide primers have been designed to amplify each exon. 
Abnormal elution profiles are sequenced to determine the specific 
mutation.

CPT Code:

83891, 83894, 83898 (x20), 83903 (x20), 83904 (x5), 83912