Unravelling the genetics of stuttering

Researchers from the NHMRC Centre of Research Excellence in Speech and Language are calling for 3,000 Australians aged seven and above with experience of stuttering (past or present) to volunteer for the nation's largest ever Genetics of Stuttering Study.

The study aims to pinpoint the genes that predispose individuals to stuttering, which could revolutionise future research into the causes, treatment and prevention of the disorder.

Winner of The Voice Australia 2013 who has lived with stuttering since childhood, Harrison Craig, now 23 and living in Melbourne, is teaming with study researchers and those who stutter nationwide today, to lend his voice to this worthy cause.

Murdoch Children's Research Institute, Walter and Eliza Hall Institute of Medical Research, QIMR Berghofer Medical Research Institute, Griffith University and the University of Melbourne are coordinating the Australian arm of this international study which involves 10 investigators at eight sites in Australia, the UK and The Netherlands. Recruitment closes December 2019. 

According to Murdoch Children's Professor Angela Morgan, Co-Chief Study Investigator, speech pathologist and NHMRC Practitioner Fellow, boys and girls aged seven and above, together with men and women nationwide who have a history of stuttering, may volunteer for the study.

"We are urgently seeking volunteers for our ground-breaking Genetics of Stuttering Study. Participation in our study is free and easy. Volunteers simply complete a 10-minute online survey and record a short sample of their speech. Those who qualify will be invited to provide a saliva sample for DNA analysis, to enable researchers to unravel the genes that predispose people to stuttering. Study participants will be making a genuine contribution to solving this disorder."

Stuttering is a disability that affects normal verbal fluency and verbal communication, particularly the rhythm or flow of speech.

Although the exact cause of stuttering is unknown, genetics has been found to play a role, and a number of genetic variants have been identified to date.

"Globally, 1 per cent of adults stutter, and nearly 70 per cent of people who stutter report a family history of the disorder," said Professor Morgan.

"Importantly, gender is one of the strongest predisposing factors for stuttering. Boys are two-to-five times more likely to stutter than girls, and they are also less likely to recover spontaneously."

Harrison's family first identified his stutter at around four years of age while listening to him speak, and watching him "get stuck" when expressing certain sounds or words. Harrison continued to combat the speech disorder throughout childhood, adolescence, and into adulthood, and still recalls the anxiety he experienced when speaking publicly, or in social situations. Post-diagnosis, Harrison underwent rigorous treatment to learn how to better control his stutter.

"My treatment to date, has been effective to a degree, but I'm not sure free speech will ever come naturally to me. The truth is, to simply speak in social situations can be very exhausting," Harrison said.

It was through music that Harrison finally found his true voice, especially after winning The Voice Australia 2013.

"To win The Voice Australia was something so special. I was really overwhelmed with happiness when I won," said Harrison.

Harrison is lending his voice to the Australian Genetics of Stuttering Study to make a genuine difference in the lives of Australians who, like Harrison, live with stuttering.

"Very little is understood about why people stutter, but I have faith that Professor Morgan and her associate researchers can make strong progress towards unlocking the mysteries of the human brain, and in turn, stuttering," Harrison said.

Australians who currently stutter, or have a history of stuttering, and wish to volunteer for the Genetics of Stuttering Study, or to learn more, can visit the study website or email

Volunteers must be:

  • Male or female
  • Aged seven and above
  • Currently stutter or have a history of stuttering