In parallel studies in human and mouse, two groups of researchers have come to the same conclusion: that a new kind of gene is associated with progressive hearing loss. The new gene - called a microRNA - is a tiny fragment of RNA that affects the production of hundreds of other molecules within sensory hair cells of the inner ear.
The research provides important new genetic understanding of a condition that is common in humans but remains poorly understood.
One team, led by researchers from the Hospital Ramn y Cajal, Madrid, Spain, followed families who showed hearing loss. The second team, led by researchers from the Wellcome Trust Sanger Institute, Cambridge, UK, examined a new line of mice, called diminuendo, that showed progressive hearing loss from an early age. The two groups shared their emerging data.
"We were able quite quickly to show that if the mice carried one copy of the gene variant they suffered progressive hearing loss, if they carried two variants they were profoundly deaf," explains Professor Karen Steel, principal investigator of the programme at the Wellcome Trust Sanger Institute. "The important questions were could we determine what the variant is and how does it exert its effect on hearing?"
In their studies of families with progressive hearing loss, the Spanish team had proposed that the gene responsible lay on human chromosome 7. Both teams set about sequencing every gene in the equivalent genomic regions in human and mouse identified as implicated in hearing loss; the sequencing showed that most of the genes in the region could not be responsible for hearing loss.
However, they each found that a mutation in a microRNA gene called miR-96 was associated with the hearing loss.
"We know of a number of genes involved in deafness in humans and mice but, to our great surprise, this was one of a new class of genes called microRNAs," explains Professor Miguel Angel Moreno-Pelayo, senior
|Contact: Don Powell|
Wellcome Trust Sanger Institute