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Neuro-rehabilitation Approach for Sudden Sensorineural Hearing Loss
Published on: January 25, 2016
Sensorineural Hearing Loss in Patients With the m.1555A>G Mutation in the MTRNR1 Gene
Jaime Gallo-Terán1, Cristina Salomón-Felechosa2, Rocío González-Aguado3
1Department of Radiology, Marqués de Valdecilla University Hospital, Santander, Spain.
Objective:
Mutations in the MTRNR1 gene of mitochondrial DNA are associated with non-syndromic hearing loss and increased susceptibility to aminoglycoside ototoxicity. The aim of our study was to determine the clinical characteristics of sensorineural hearing loss caused by the m.1555A>G mutation in MTRNR1.
Methods:
An observational retrospective study of the m.1555A>G mutation was conducted in patients with suspected hereditary bilateral sensorineural hearing loss in the Department of Otolaryngology of the Marqués de Valdecilla University Hospital (Cantabria, Spain) and in 100 controls with normal hearing.
Results:
The m.1555A>G mutation was found in 82 individuals from 20 different families and in none of the controls. Variable degrees of hearing loss were observed, ranging from normal hearing to profound deafness. Patients with a history of streptomycin administration exhibited significantly more pronounced hearing loss. The onset of hearing loss occurred from childhood to adulthood, with progression or stability over the years. No associated vestibular alterations or other clinical manifestations outside the ear were found. Two cochlear implant recipients showed significant improvement in speech comprehension.
Conclusions:
Patients with the m.1555A>G mutation in the MTRNR1 gene often develop bilateral, symmetric sensorineural hearing loss, predominantly affecting high frequencies, worsened by streptomycin administration. This mutation does not affect the vestibular function. The variability in the severity of hearing loss, the heterogeneity of phenotypic expression, and the presence of carrier individuals with normal hearing may indicate the existence of modifying factors, both environmental and genetic. Cochlear implantees showed a good response in terms of speech intelligibility. Genetic testing for this mutation is recommended in patients with a family history of hearing loss to prevent the use of aminoglycosides if the mutation is found.
Level Of Evidence:
4 Laryngoscope, 135:901-907, 2025.
Insights
The m.1555A>G mutation in the MTRNR1 gene causes hereditary hearing loss, often worsened by streptomycin. Genetic testing is recommended to prevent ototoxicity in affected families.
Area of Science:
- Genetics
- Otolaryngology
- Audiology
Background:
- Mitochondrial DNA mutations, specifically in MTRNR1, are linked to non-syndromic hearing loss.
- Aminoglycoside antibiotics can exacerbate hearing loss in individuals with these mutations.
- The m.1555A>G mutation is a known cause of sensorineural hearing loss.
Purpose of the Study:
- To investigate the clinical characteristics of sensorineural hearing loss attributed to the m.1555A>G mutation in the MTRNR1 gene.
- To identify potential modifying factors influencing the phenotype of hearing loss.
- To assess the efficacy of cochlear implantation in affected individuals.
Main Methods:
- Observational retrospective study design.
- Analysis of the m.1555A>G mutation in patients with suspected hereditary bilateral sensorineural hearing loss.
- Comparison with a control group of 100 individuals with normal hearing.
Main Results:
- The m.1555A>G mutation was identified in 82 individuals across 20 families, with no presence in controls.
- Hearing loss severity varied from normal to profound, with streptomycin exposure correlating with more severe loss.
- Onset ranged from childhood to adulthood, with hearing loss showing progression or stability; no vestibular or extra-aural manifestations were observed.
Conclusions:
- The m.1555A>G MTRNR1 mutation frequently results in bilateral, symmetric sensorineural hearing loss, primarily affecting high frequencies and exacerbated by streptomycin.
- Vestibular function remains unaffected by this mutation.
- Phenotypic variability suggests environmental and genetic modifiers; cochlear implantation offers good speech intelligibility outcomes. Genetic screening is advised for families with hearing loss history.
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