Aminoglycoside-induced Hearing Loss

Disorder Aminoglycoside-induced hearing loss
Gene Name MTRNR1
Clinical info Exposure to aminoglycoside antibiotics such as gentamycin and tobramycin can lead to sensorineural, bilateral, and severe-to-profound hearing loss.  A single base-pair substitution from an A to a G at position 1555 in the MTRNR1 gene (encoding 12S ribosomal RNA) predisposes individuals to aminoglycoside ototoxicity.  Evidence has shown that even a single dose of an aminoglycoside antibiotic results in irreversible hearing loss in Individuals with this mutation.  The hearing loss is not dependent on aminoglycoside exposure.  Approximately 40% of individuals with the A1555G mutation who have not been treated with aminoglycosides will develop hearing loss by 30 years of age, and the penetrance increases to 80% by age 65. The MTRNR1 gene is located within mitochondrial DNA, and the A1555G mutation is, therefore, transmitted by maternal inheritance.  The mutation occurs as a homoplasmic change and has a prevalence of approximately 1% in the U.S. population.
Indications Molecular testing is useful to confirm the diagnosis.
Specimen Requirements 5 to 10 ml of peripheral blood collected in an EDTA (lavender top) Vacutainer tube is preferred. The minimal blood needed for reliable DNA isolation is 3 ml.
Transport The specimen should be kept at room temperature and delivered via overnight shipping. FedEx is preferred. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.
Turnaround time 2 weeks
CPT Codes 81401
Cost $350
Contact For further information contact one of our This email address is being protected from spambots. You need JavaScript enabled to view it. at 1-800-473-9411.

Cytogenetics Lab

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