MTRNR1 (OMIM# 561000)
Hearing loss as a result of aminoglycoside exposure (OMIM# 580000) has been reported to involve at least 2 mitochondrial variants, C1494T and A1555G of the 12S rRNA gene. Damage to the inner ear is caused by reactive oxygen species, which provide a common pathway not only for aminoglycoside toxicity, but also for cisplatin toxicity and noise-induced hearing loss. MORL offers screening for both of these variants.

Indications for screening
This test is appropriate if aminoglycoside-induced ototoxcicity is suspected.

Samples are amplified with an oligonucleotide primer pair that flanks the A1555G and C1494T variants within the MTRNR1 gene, followed by sequencing.

Sensitivity is greater than 99%.

Turnaround time
Turnaround time is approximately 3 months (Average TAT - 26 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

Other Web Sites:


  • 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
  • Zhao, H. et al: Maternally inherited aminoglycoside-induced and nonsyndromic deafness is associated with the novel C1494T mutation in the mitochondrial 12S rRNA gene in a large Chinese family. Am. J. Hum. Genet. 74: 139-152, 2004. PubMed ID: 14681830

The Clinical Diagnostics Service of the Molecular Otolaryngology and Renal Research Laboratories is a Joint Commission-approved CLIA-accredited diagnostic laboratory.