rs267606617 (MT-RNR1)

What you carry at this position in your DNA and what research says about it.

Antibiotic Hearing Loss: 9/10 evidence, 8 publications.

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Sample genotype (not yours): A

Typical Risk of Antibiotic-Induced Hearing Loss

This maternal lineage variant is the typical version of the gene. It does not increase susceptibility to hearing damage from aminoglycoside antibiotics.

What this genotype means: Typical response to aminoglycoside antibiotics; No elevated genetic risk of mitochondrial deafness.

Sample genotype (not yours): G

High Risk of Antibiotic-Induced Hearing Loss

Carrying this maternal variant significantly increases the risk of permanent hearing loss after taking aminoglycoside antibiotics. Exposure to drugs like gentamicin can cause rapid, irreversible inner ear damage.

What this genotype means: Irreversible hearing loss after aminoglycoside exposure; Increased risk of progressive sensorineural hearing loss; Potential risk of maternally inherited cardiomyopathy.

About MT-RNR1

Gene function and biological role

Gene Function: The MT-RNR1 gene encodes the mitochondrial 12S ribosomal RNA, which is essential for assembling the protein-synthesizing machinery inside mitochondria [1]. This ribosomal RNA helps translate the genetic instructions needed to produce energy-generating complexes [1]. Because mitochondria are inherited exclusively from the mother, any variants in this gene are passed down along the maternal line [2]. When this gene functions normally, it allows cells to generate energy efficiently without being vulnerable to common antibiotics [1]. However, certain changes in its structure can make the mitochondrial ribosome resemble bacterial ribosomes, creating an unintended target for specific medications [1].

Variant Impact: The rs267606617 variant, commonly known as m.1555A>G or A1555G, is a single-nucleotide change in the MT-RNR1 gene [1]. This change alters the structure of the mitochondrial 12S rRNA at the aminoacyl-tRNA acceptor site [1]. The structural alteration makes the human mitochondrial ribosome highly similar to the bacterial ribosome [1]. As a result, certain antibiotics designed to target bacteria can bind to human mitochondrial ribosomes instead, halting protein synthesis and leading to cell death in the inner ear [1] [3]. This variant is a well-known maternal genetic risk factor for permanent hearing loss [2].

Key Insight: A single dose of common antibiotics like gentamicin can trigger permanent, severe hearing loss in individuals carrying the risk variant. The risk variant makes human mitochondrial structures look almost identical to bacteria, causing antibiotics to accidentally target the inner ear.

Allele Frequencies

Estimated prevalence by population

No frequency data available

This variant is not present in the gnomAD database.

Associated Traits

Showing effects for A genotype

Organ Systems

Hearing & Balance

Antibiotic Hearing Loss. Evidence: 9/10. Source: PMID 25515069. Typical Risk.

Nonsyndromic Hearing Loss. Evidence: 9/10. Source: PMID 12920080. Typical Risk.

Pharmacogenomics

Antimicrobial & Antiviral Response

Gentamicin Toxicity. Evidence: 8/10. Source: PMID 25155176. Typical Response.

Cardiovascular & Metabolic

Heart Disease

Cardiomyopathy. Evidence: 9/10. Source: PMID 9915970. Typical Risk.

Showing effects for G genotype

Antibiotic Hearing Loss. Evidence: 9/10. Source: PMID 25515069. High Risk.

Nonsyndromic Hearing Loss. Evidence: 9/10. Source: PMID 12920080. Increased Risk.

Gentamicin Toxicity. Evidence: 8/10. Source: PMID 25155176. High Toxicity Risk.

Cardiomyopathy. Evidence: 9/10. Source: PMID 9915970. Increased Risk.

What A Genotype Means

What this genotype means for the people who carry it

Sample genotype: A (Single copy)

Carrying the A allele at this mitochondrial position represents the typical genetic state found in over ninety-nine percent of the global population. Individuals with this allele do not have the structural mitochondrial ribosome changes that make them vulnerable to aminoglycoside-induced ototoxicity [1]. Standard clinical guidelines indicate a normal risk of hearing loss when exposed to medications like gentamicin or streptomycin [2]. While general medical precautions regarding antibiotic side effects still apply, there is no elevated genetic risk of sudden, permanent deafness from these drugs [1]. Additionally, this typical allele is not associated with maternally inherited nonsyndromic hearing loss or restrictive cardiomyopathy [3] [4].

Typical response to aminoglycoside antibiotics; No elevated genetic risk of mitochondrial deafness.

What G Genotype Means

Sample genotype: G (Single copy)

The G allele is a well-documented mitochondrial variant that alters the 12S rRNA structure, making mitochondrial ribosomes highly sensitive to aminoglycoside antibiotics [1]. Clinical studies show that individuals carrying this variant are at extremely high risk of developing permanent, bilateral sensorineural hearing loss after receiving even a single dose of these medications [2] [3]. The hearing damage typically manifests within weeks to months following exposure [4]. Additionally, some individuals with this variant may develop progressive hearing loss over time even without antibiotic exposure [5]. In rare cases, this variant has also been linked to maternally inherited restrictive cardiomyopathy [6].

Irreversible hearing loss after aminoglycoside exposure; Increased risk of progressive sensorineural hearing loss; Potential risk of maternally inherited cardiomyopathy.

Related Variants

Variants with shared genetic architecture

rs267606618 · Chr M · Antibiotic Hearing Loss Risk

rs1465618 · THADA Gene · Chr 2 · Prostate Cancer Risk

rs1569419 · PRDM16 Gene · Chr 1 · Blood Cell Traits

Sources

Mutant mtDNA at 1555 A to G in 12S rRNA gene and hypersusceptibility of mitochondrial translation to streptomycin can be co-transferred to rho 0 HeLa cells.

Familial progressive sensorineural deafness is mainly due to the mtDNA A1555G mutation and is enhanced by treatment of aminoglycosides.

Cochlear alterations in deaf and unaffected subjects carrying the deafness-associated A1555G mutation in the mitochondrial 12S rRNA gene.

Mitochondrial mutations associated with aminoglycoside ototoxicity and hearing loss susceptibility identified by meta-analysis.

Mitochondrial mutation m.1555A>G as a risk factor for failed newborn hearing screening in a large cohort of preterm infants.

Heteroplasmy for the 1555A>G mutation in the mitochondrial 12S rRNA gene in six Spanish families with non-syndromic hearing loss.

Maternally inherited cardiomyopathy: an atypical presentation of the mtDNA 12S rRNA gene A1555G mutation.

Mutation in the mitochondrial 12S rRNA gene in two families from Mongolia with matrilineal aminoglycoside ototoxicity.

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Content updated August 2026.

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