Fifty-two genes critical for hearing identified

Scientists have discovered 52 previously unidentified genes critical for hearing by testing over 3,000 mouse genes, an advance that will provide insights into the causes of hearing loss in humans.
The study, published in the journal Nature Communications, tested 3,006 strains of 'knock-out' mice for signs of hearing loss.
'Knock-out' mice have one gene from their genome inactivated, which helps researchers to uncover the functions of that gene.
"Importantly, the large number of hearing loss genes identified in this study demonstrates that there are many more genes involved in deafness in mouse and human genomes than we had previously realised," said Steve Brown, Director of Medical Research Council (MRC) Harwell in the UK.

The hearing thresholds of the knock-out mice were assessed with rising volumes of sound at five different frequencies - mice were considered hearing impaired if they could not hear the quieter sounds for two or more frequencies.
They identified 67 genes that were associated with hearing loss, of which 52 had not been previously linked with hearing loss.

The genes identified varied in how they affected hearing - effects ranged from mild to severe hearing loss or resulted in difficulties at lower or higher frequencies.
The knock-out mice tested in the study represented only about 15 per cent of mouse genes, so the researchers estimate that if the entire genome is searched there will be at least 450 genes required for hearing function.

In humans, there are over 400 genetic syndromes that include a hearing loss component, however most of the genes underlying hearing loss syndromes are currently unknown.
"Our findings identify 52 genes that have previously not been recognised as being critical for hearing," said Brown.
"These increase our knowledge of the many genes and molecular mechanisms required for hearing, and also provide a shortlist of new genes to investigate to discover the genetic basis of many human hearing loss syndromes.
"Testing these genes in people with hearing loss may help to improve diagnosis and counselling of patients," he said.