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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed November 2006

What is the official name of the MT-RNR1 gene?

The official name of this gene is “mitochondrially encoded 12S RNA.”

MT-RNR1 is the gene's official symbol. The MT-RNR1 gene is also known by other names, listed below.

What is the normal function of the MT-RNR1 gene?

The MT-RNR1 gene provides instructions for making a particular type of RNA, a molecule that is a chemical cousin of DNA. This type of RNA, known as ribosomal RNA (rRNA), is involved in the assembly of proteins within cells.

The MT-RNR1 gene provides instructions for a specific form of ribosomal RNA called 12S RNA, which is present only in cellular structures called mitochondria. These structures convert energy from food into a form that cells can use. Through a process called oxidative phosphorylation, mitochondria use oxygen and simple sugars to create adenosine triphosphate (ATP), the cell's main energy source. 12S RNA molecules help assemble protein building blocks (amino acids) into the functioning proteins that carry out oxidative phosphorylation.

How are changes in the MT-RNR1 gene related to health conditions?

nonsyndromic deafness - increased risk from variations of the MT-RNR1 gene

Several mutations in the MT-RNR1 gene can increase the risk of developing nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body). If people with MT-RNR1 mutations are exposed to antibiotic medications known as aminoglycosides, they almost always develop permanent hearing loss within days to weeks of taking the medication. This group of antibiotics is typically used to treat chronic bacterial infections such as tuberculosis. Deafness resulting from exposure to these antibiotics is known as aminoglycoside ototoxicity.

Aminoglycosides treat infections by killing the bacteria that cause illness. These antibiotics are designed to kill bacteria by binding to their ribosomal RNA and disrupting the bacteria's ability to make proteins. Most mutations in the MT-RNR1 gene change single building blocks (nucleotides) in the 12S RNA molecule, which often makes the human 12S RNA look very similar to bacterial ribosomal RNA. As a result, aminoglycosides can target the 12S RNA molecule in human cells just as they target bacterial ribosomal RNA. The antibiotic easily binds to the abnormal 12S RNA, which impairs the ability of mitochondria to produce proteins needed for oxidative phosphorylation. Researchers believe that this unintended effect of aminoglycosides may reduce the amount of ATP produced in mitochondria, increase the production of harmful byproducts, and eventually cause the cell to self-destruct (undergo apoptosis). It is unknown why damage caused by aminoglycosides is often limited to cells in the inner ear that are essential for hearing.

Some people with mutations in the MT-RNR1 gene experience hearing loss even if they are never exposed to aminoglycosides. In these cases, problems with hearing usually begin in early adulthood. Studies suggest that other genetic and environmental factors play an important role in determining whether people with changes in the MT-RNR1 gene will develop hearing loss.

Where is the MT-RNR1 gene located?

The MT-RNR1 gene is located in mitochondrial DNA.

Molecular Location in mitochondrial DNA: base pairs 648 to 1,601

Overview of gene located on mitochondrial DNA Close-up of gene located on mitochondrial DNA

Where can I find additional information about MT-RNR1?

You and your healthcare professional may find the following resources about MT-RNR1 helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the MT-RNR1 gene or gene products?

  • 12S RNA
  • MTRNR1

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding MT-RNR1?

acids ; adenosine triphosphate ; aminoglycoside ; antibiotics ; apoptosis ; ATP ; bacteria ; cell ; chronic ; DNA ; gene ; mitochondria ; molecule ; ototoxicity ; oxidative phosphorylation ; oxygen ; pharmacogenomics ; phosphorylation ; protein ; reactive oxygen species ; ribosomal RNA ; RNA ; tuberculosis

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Fischel-Ghodsian N, Kopke RD, Ge X. Mitochondrial dysfunction in hearing loss. Mitochondrion. 2004 Sep;4(5-6):675-94. Epub 2004 Nov 6. (
  • Fischel-Ghodsian N. Genetic factors in aminoglycoside toxicity. Pharmacogenomics. 2005 Jan;6(1):27-36. Review. (
  • Fischel-Ghodsian N. Mitochondrial deafness. Ear Hear. 2003 Aug;24(4):303-13. Review. (
  • Gene Review: Nonsyndromic Hearing Loss and Deafness, Mitochondrial (
  • Giordano C, Pallotti F, Walker WF, Checcarelli N, Musumeci O, Santorelli F, d'Amati G, Schon EA, DiMauro S, Hirano M, Davidson MM. Pathogenesis of the deafness-associated A1555G mitochondrial DNA mutation. Biochem Biophys Res Commun. 2002 Apr 26;293(1):521-9. (
  • Guan MX. Molecular pathogenetic mechanism of maternally inherited deafness. Ann N Y Acad Sci. 2004 Apr;1011:259-71. (
  • NCBI Gene (
  • Van Camp G, Smith RJ. Maternally inherited hearing impairment. Clin Genet. 2000 Jun;57(6):409-14. Review. (
  • Zhao H, Young WY, Yan Q, Li R, Cao J, Wang Q, Li X, Peters JL, Han D, Guan MX. Functional characterization of the mitochondrial 12S rRNA C1494T mutation associated with aminoglycoside-induced and non-syndromic hearing loss. Nucleic Acids Res. 2005 Feb 18;33(3):1132-9. Print 2005. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: November 2006
Published: November 23, 2015