MT-RNR1 Gene and Aminoglycosides

What is MT-RNR1? 

MT-RNR1 is a gene that can affect how your body interacts with certain medicines. Genes are segments of DNA that act as a set of instructions and tell the body how to work. Differences in the MT-RNR1 gene can affect how you respond to a type of medicine called aminoglycosides. 

Aminoglycosides and hearing loss risk 

Antibiotics are medicines used to treat some infections. A class of antibiotics called aminoglycosides includes medicines such as: 

• amikacin 
• gentamicin 
• plazomicin 
• streptomycin 
• tobramycin  

Aminoglycosides are effective antibiotics, but they can cause serious side effects, including hearing loss. In some patients, the hearing loss can be permanent.  

It is hard to know which patients are at risk of hearing loss from aminoglycosides. If your doctors or pharmacists know in advance that someone is at a very high risk of hearing loss, they might be able to use a different type of antibiotic. One way to see if someone is at a high risk of hearing loss is to look for DNA changes in a gene called MT-RNR1. 

Pharmacogenomic testing 

Each person differs from another at the DNA level. Genes are segments of DNA that act as a set of instructions and tell the body how to work. The study of how genes like MT-RNR1 affect the way your body interacts with medicines is called pharmacogenomics. Doctors may order a pharmacogenomic test to find out which medicines and which doses are safe and most effective for you.  

Differences in your DNA that make up the MT-RNR1 gene can increase your risk of developing hearing loss from aminoglycosides. A pharmacogenomic test looks for these differences. The test may find changes that help predict if you are at high risk of hearing loss from aminoglycosides. The test results can help your doctor and pharmacist choose the correct type or dose of medicine to give you. 

MT-RNR1 groups   

The results of your MT-RNR1 pharmacogenomic test will place you into one of two groups: 

• Increased Risk of Aminoglycoside-Induced Ototoxicity: This means you have a high-risk MT-RNR1 gene change that increases your chance of hearing loss after taking these antibiotics. About 2 in 1000 people are in this group.  
• Normal Risk of Aminoglycoside-Induced Ototoxicity: This means the test did not find the MT-RNR1 gene change that increases the chance of hearing loss. Most people (99 in 100 people) fall into this group. 

It is important to know that these antibiotics might still cause hearing loss for people in the lower risk group. Talk to your doctor or pharmacist if you have questions about your medicines, side effects, or pharmacogenomic testing.  

Find more information about genes that are being used to make drug therapy decisions for patients at St. Jude.   

If you have questions about pharmacogenomic testing done at St. Jude, you can email the Clinical Pharmacogenomics Program at pharmacogenomics@stjude.org.