School of Medicine

Department of Genetics

A1555G Mitochondrial Mutation

Danielle Mercer1, Fern Tsien2, and Barbara Gordon-Wendt1

1 Department of Communication Disorders, LSUHSC School of Allied Health Professions
2 Department of Genetics, LSUHSC School of Medicine


A1555G is a mitochondrial mutation that can cause hearing loss.  A1555G is the most common mitochondrial mutation causing hearing loss.  The carrier rate is highest in Asian populations.  About half of individuals with this mutation develop hearing loss, usually after age 30.  However, hearing loss can occur much earlier if a person with this mutation receives aminoglycoside antibiotics.  If possible, patients should be screened for this mutation before the administration of aminoglycoside antibiotics.  Of course, a life-threatening illness may require this type of treatment.  The following antibiotics are aminoglycosides:

  • amikacin
  • dihydrostreptomycin
  • gentamicin
  • kanamycin
  • neomycin
  • streptomycin
  • tobramycin

The type of hearing loss is sensorineural.  The degree of hearing loss can vary from mild to profound, but is likely to be severe to profound if the individual is exposed to aminoglycoside antibiotics.  Since this is a mitochondrial mutation, it is inherited from the mother.     


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