Genetic Screening Would Prevent Hearing Loss Caused by Antibiotics

Hearing loss caused by a group of antibiotics called aminoglycosides could be prevented if patients were screened for a genetic mutation before treatment, say experts in this week’s BMJ.

Aminoglycosides are most useful for the treatment of serious infections, such as septicaemia, complicated urinary tract infections, and tuberculosis.

Their potential for ototoxicity (damage to the ear) is well known, but less well known is that some people have an inherited predisposition that renders them highly sensitive to these effects and can result in severe and permanent hearing loss, write Maria Bitner-Glindzicz and Shamima Rahman at the Institute of Child health in London.

The mutation, known as m.1555A-G is thought to cause up to 5% (1 in 40,000) cases of deafness in children in the UK. This is low compared to other countries. Studies from New Zealand and the US, for example, found between 1 in 206 and 1 in 1,161 positive cases in newborns.

Even in the absence of exposure to aminoglycosides, some families carrying this mutation may also develop deafness, albeit at a later age and with a lower penetrance.

In Spain, for example, 27% of families with at least two deaf individuals were positive for this mutation and everyone with the mutation who was exposed to aminoglycosides became deaf. By the age of 30, the probability of becoming deaf if an individual had received such antibiotics was 96.5% compared with 39.9% if they had never been treated.