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Mitochondrially Encoded 12S RNA (mt-RNR1)

PG4KDS Implemented Genes

mt-RNR1 is a gene in the mitochondrial DNA that produces a type of ribosome (called 12S rRNA). There are several variations in the mt-RNR1 gene that can change the structure of ribosomes. Some of these changes can make the human ribosome look very similar to the ribosome of bacteria.

A class of antibiotics called aminoglycosides (e.g. amikacin, gentamicin, neomycin, paromomycin, plazomicin, streptomycin, and tobramycin) work by attacking the ribosome of bacteria. In patients who have differences in the mt-RNR1 gene, aminoglycoside antibiotics also attack the human ribosomes. This can put the patient at very high risk of hearing loss from aminoglycoside antibiotics. Clinicians use this information to help guide drug therapy decisions.

Clinicians classify patients into 2 categories based on their mt-RNR1 status to help guide decisions on aminoglycoside use.

Priority mt-RNR1 phenotype

  • Increased risk of developing hearing loss due to aminoglycosides–These patients are at very high risk of experiencing permanent hearing loss from aminoglycoside antibiotics, even after a single dose. Aminoglycoside antibiotics should be avoided if possible. About 1 in 500 people have this mt-RNR1 phenotype.

Routine phenotype

  • Normal risk of developing hearing loss due to aminoglycosides– There is no reason to avoid aminoglycoside antibiotics based on mt-RNR1 phenotype alone. It should be noted that patients in this category can still develop hearing loss from the use of aminoglycoside antibiotics.

More information for patients

  • Do you know... mt-RNR1 and aminoglycosides
  • If you have questions or concerns about pharmacogenetic testings done at St. Jude,  you can email the pharmacogenetics team at, or call one of the Pharmaceutical Sciences Research Nurses at 901-595-2482. If you are calling from outside of the Memphis area, dial toll free 1-866-2ST-JUDE (1-866-278-5833), then dial extension 2482.

More information for healthcare professionals

Legal Disclaimer: This page is intended to provide implementers with guidance on establishing a clinical pharmacogenetic program at their institution. Information contained on this page is for information and educational purposes only. Although reasonable efforts have been made to ensure that the information provided on this page is current, complete and, where appropriate, based on scientific evidence, St. Jude Children's Research Hospital makes no assurances as to whether the provided information will at all times be current or complete. St. Jude Children's Research Hospital, in offering this document, is not providing medical advice or offering a consultative opinion, and is not establishing a treatment relationship with any given individual. You, therefore, should not substitute information contained herein for your own professional judgment, nor should you rely on information provided herein in rendering a diagnosis or choosing a course of treatment for a particular individual.