More than 1500 adults and children from the United Kingdom are being recruited for an international study aiming to discover the genes that cause stammering.
The largest study of its kind hopes to provide greater insight into why some people are more likely to develop a stammer, also known as stuttering, in a bid to develop new treatments that target the cause rather than just the symptoms.
As well as experts from the UK, research teams from New Zealand, Australia, the US and the Netherlands are also seeking people aged five and older who stammer or have a history of stammering for the Genetics of Stuttering Study. Stammering, which causes frequent and significant problems with normal fluency and flow of speech, affects one in 100 adults.
WEHI (Walter and Eliza Hall Institute of Medical Research), the Murdoch Children's Research Institute, QIMR Berghofer Medical Research Institute, Griffith University and the University of Melbourne are co-ordinating the global project. University College London (UCL) will oversee the UK arm of the study.
UCL Associate Professor Frederique Liegeois said study participants would contribute to a global effort to better understand the genetics behind stammering.
Learning more about the genetic basis will help us identify who may be more likely to develop stammering."
Frederique Liegeois, UCL Associate Professor
WEHI and the University of Melbourne Professor Melanie Bahlo said stammering typically emerged in children between two and four years of age after they had begun to speak.
"About 4 per cent of children experience a phase during which they prolong words or get stuck trying to talk," she said. Studies show that 8 per cent of three-year-olds and 11 per cent of four-year-olds stammer."
Murdoch Children's and University of Melbourne Professor Angela Morgan said although the exact cause of stammering was unknown, genetics had been found to play a role and researchers had identified four genes that may be linked to the condition.
"Globally, 1 per cent of adults stammer and nearly 70 per cent of those who do report a family history of stammering," she said. But even for people where the disorder doesn't run in the family, genetics can still be playing a role.
"Gender is one of the strongest predisposing factors for stammering. Boys are two to five times more likely to stutter than girls and are also less likely to stop stammering without therapy.
"Many stammering treatments focus on symptoms only, without targeting the underlying causes. We hope this research will develop new therapies for those who want to access treatment to help better manage their stammer and learn to speak more easily."
To take part in the trial, volunteers need to complete a 10-minute online survey. Those who meet the study criteria will be asked to provide a saliva sample for DNA analysis. People who stammer, both with and without a family history, are encouraged to take part.
Participants will be kept informed with fortnightly updates via the study website and can follow the Facebook page or Twitter account for updates.