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Familial streptomycin ototoxicity in a South African family: a mitochondrial disorder
J C Gardner1, R Goliath, D Viljoen
1Department of Human Genetics, University of Cape Town Medical School, Observatory, South Africa.
Abstract:
The vestibular and ototoxic effects of the aminoglycoside antibiotics (streptomycin, gentamycin, kanamycin, tobramycin, neomycin) are well known; streptomycin, in particular, has been found to cause irreversible, profound, high frequency sensorineural deafness in hypersensitive persons. Aminoglycoside ototoxicity occurs both sporadically and within families and has been associated with a mitochondrial DNA (mtDNA) 1555A to G point mutation in the 12S ribosomal RNA gene. We report on the molecular analysis of a South African family with streptomycin induced sensorineural deafness in which we have found transmission of this same predisposing mutation. It is now possible to identify people who are at risk of hearing loss if treated with aminoglycosides in the future and to counsel them accordingly. In view of the fact that aminoglycoside antibiotics remain in widespread use for the treatment of infections, in particular for tuberculosis, which is currently of epidemic proportions in South Africa, this finding has important implications for the family concerned. In addition, other South African families may potentially be at risk if they carry the same mutation.
Insights
A specific genetic mutation predisposes individuals to hearing loss from streptomycin. Identifying this mutation allows for risk assessment and counseling for patients, particularly in South Africa where tuberculosis is prevalent.
Area of Science:
- Genetics
- Pharmacology
- Otolaryngology
Background:
- Aminoglycoside antibiotics are known to cause ototoxicity, leading to hearing loss.
- A specific mitochondrial DNA mutation (1555A to G) in the 12S ribosomal RNA gene is linked to aminoglycoside-induced hearing loss.
- This ototoxicity can be sporadic or familial.
Purpose of the Study:
- To investigate the genetic basis of streptomycin-induced sensorineural deafness in a South African family.
- To identify individuals at risk for aminoglycoside ototoxicity.
Main Methods:
- Molecular analysis of a South African family.
- Genetic testing for the 1555A to G mitochondrial DNA mutation.
Main Results:
- The study identified the transmission of the 1555A to G mutation in the South African family.
- This mutation predisposes individuals to streptomycin-induced sensorineural deafness.
Conclusions:
- The findings highlight the importance of genetic screening for the 1555A to G mutation to identify individuals at risk of hearing loss from aminoglycosides.
- This has significant implications for patient counseling and treatment strategies, especially in regions with high tuberculosis rates like South Africa.