Specimen:

Whole Blood

Collection Medium:

Minimum:

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

Analytic Time:

3 months

Reference Range:

None detected

Interpretive Data:

DFNA8/12
Linkage studies identified a region on chromosome 11q22-24 as the site 
of a deafness-causing gene in families segregating pre-lingual 
autosomal dominant nonsyndromic hearing loss that is most severe in the 
mid-frequencies. Audiograms displaying this type of hearing loss may be 
referred to as "cookie-bite" audiograms. TECTA has been identified as 
the causally-related gene at this locus.

DFNB21
Mustapha and colleagues studied a Lebanese family with pre-lingual, 
severe-to-profound autosomal recessive nonsyndromic hearing loss 
mapping to chromosome 11q23-q25 (Mustapha et al., 1999). A splice donor 
mutation in TECTA was found to segregate with the hearing loss in this 
family.

TECTA
The gene, TECTA, contains 23 exons and encodes the 2155 amino acid 
protein TECTA (Alpha Tectorin).  Alpha Tectorin is the major 
non-collagenous component of the tectorial membrane.  In humans, 
mutations in TECTA cause both autosomal dominant and autosomal 
recessive nonsyndromic hearing loss. Over 20 mutations have been 
identified in TECTA including missense, nonsense, and splice site 
mutations.

Sensitivity is greater than 98%.

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 TECTA is performed via DHPLC and sequencing.  
Oligonucleotide primers have been designed to amplify each exon.  
Amplified samples are run on the DHPLC; abnormal elution profiles are 
sequenced to determine the specific mutation.

CPT Code:

83891, 83894, 83898 (x23), 83903 (x13), 83904 (x10), 83912