Hearing loss in the elderly has been linked to flaws in a specific gene in a study by Belgian researchers.
The gene is expressed in parts of the ear and brain
About 37% of Britons aged 61 to 70 and 60% of those aged 71 to 80 - 6.5m people - have age-related hearing loss.
The Human Mutation study of over 1,200 people found subtle changes in a gene called KCNQ4 were more common in those with age-related hearing problems.
The Royal National Institute for Deaf People, which funded the work, said it offered "real hope for treatments."
Age-related hearing loss is a complex condition, which scientists believe has both environmental and genetic causes.
The most common environmental factor is noise exposure.
Hearing loss makes it difficult for elderly people to communicate with friends and family, and can lead to them feeling increasingly isolated.
There is currently is no way of identifying those at risk or preventing the onset of hearing loss.
'Piece of the jigsaw'
Scientists already know that a mutation in KCNQ4 is linked to hereditary hearing loss which happens early in life, regardless of exposure to noise and other environmental factors.
In people with normal hearing, it is expressed in the hair cells of the cochlea where it helps recycle potassium, brought in to trigger a nerve signal to be sent to the brain, back into inner ear fluid.
The University of Antwerp team looked to see if more minor changes in KCNQ4 could play a part in age-related hearing loss.
The team looked at over 1,200 people aged between 40 and 80.
The researchers tested people's hearing and then looked at their DNA.
They found that three variations - single letter differences in DNA called single-nucleotide polymorphisms (SNPs) - were seen in people with hearing loss but not in those with normal hearing.
They say more research now needs to identify what effect these genetic spelling mistakes have. Possible explanations include causing a build up of potassium in hair cells, or causing it to be removed too quickly.
Dr Ralph Holme, the RNID's Biomedical Research Manager, said: "Many people consider hearing loss as an inevitable part of ageing, rather than a potentially preventable condition.
"This research provides another important piece of the jigsaw in highlighting a gene associated with age-related hearing loss.
"At the moment, there is nothing we can do. People can wear a hearing aid, but that doesn't prevent their hearing deteriorating.
"This offers real hope that treatments will be found and we are optimistic that in the future people will no longer face the prospect of losing their hearing as they age."