PDF iconMORL 2020 Hearing Loss Test Requisition Form (Effective January 3, 2020)

The Clinical Diagnostics Service of the Molecular Otolaryngology & Renal Research Laboratories is a CLIA-approved, Joint Commission-accredited diagnostic laboratory that offers variant screening of several genes.

MTTS1 (OMIM# *590080)
The A7445G variant in the MTTS1 gene, which encodes the transfer RNA for serine (OMIM# *590080), is associated with maternally inherited, nonsyndromic hearing loss (Reid et al., 1994). The deafness is progressive, post lingual and involves the high frequencies.

Indications for screening
This test is appropriate for a patient suspected of having maternally inherited high frequency hearing loss.

Samples are amplified with an oligonucleotide primer pair that flanks the A7445G variant within the MTTS1 gene, followed by sequencing.

Sensitivity is greater than 99%.

Turnaround time
Turnaround time is approximately 3 months (Average TAT - 24 days).

Sample Required
8 - 10 cc. whole blood in lavender (EDTA) top tubes OR 10 μg DNA, minimum concentration: 50 ng/μl (A260/A280 1.8-2) resuspended in 0.1mM EDTA (10mM Tris HC1, 0.1mM EDTA, pH 8, Teknova Cat#T0220).

Cost & CPT Codes
See the MORL Testing Menu

GeneTests GeneReviews – Nonsyndromic Hearing Loss, Mitochondrial


Reid, F. M. et al.: A novel mitochondrial point mutation in a maternal pedigree with sensorineural deafness. Hum. Mutat. 3: 243-247, 1994.
PubMed ID: 8019558
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Casano, R. A. et al.: Hearing loss due to the mitochondrial A1555G mutation in Italian families. Am J Med Genet. 79(5):388-91, 1998.
PubMed ID: 9779807
PubMed Search