Hunting the genetic cause of stuttering

Thursday, Aug 15, 2019, 02:57 AM | Source: Pursuit

Angela Morgan, Melanie Bahlo

Stuttering is more common than you might think. Around 1 in 100 adults stutter, and it is even more common among children, where around 1 in 10 will stutter between the ages of three and four.

Most children will recover from stuttering, but some may continue to stutter into adulthood.

Stuttering is more common in children, especially boys. Picture: Ashton Bingham/Unsplash

Stuttering is a speech disorder affecting the flow and rhythm of speech. It has nothing to do with a person’s intelligence or academic abilities.

People who stutter might repeat sounds, words or phrases, and prolong or stretch out sounds in words. They may also ‘block’, which is when no sound comes out for a period of time. Sometimes, there may also be physical movements, like lip tremors, hand flapping or excessive blinking.

Clearly then, stuttering in any form can significantly impact a person’s day to day life, putting them at risk of being stigmatised by people who may not understand the condition.


There are a number of treatment programs available for people who stutter, depending on their age. There are two broad types of treatment that have been researched extensively: The Lidcombe Program (for pre- and early primary school aged children) and Smooth Speech Treatment (school-aged children and adults).

While many children recover naturally from stuttering, we are unable to predict who these children will be. Because of this, early intervention from speech pathologists is highly recommended.

There are a number of treatment programs available for people who stutter, depending on their age. Picture: Getty Images

At the moment however, we are only able to treat the speech or surface symptoms of stuttering. This is because we still don’t know what precisely causes stuttering, preventing the development of treatments targeting the underlying causes.

We do know however, that stuttering can run in families, suggesting that genes are involved. Globally, almost 70 per cent of adults who stutter report a family history of the disorder.

So far, researchers have identified four specific genes associated with stuttering. Changes or mutations in these genes have been associated with stuttering in a small number of families where multiple members stutter.

Yet we don’t yet understand how important these genes are for the broader population of people who stutter.

For most people, we don’t expect a single gene to be responsible for their stutter. Rather, current evidence suggests that stuttering is a complex trait, meaning that it is may be associated with multiple genes being affected at once (polygenic) or may also be due to gene and environment interactions (epigenetic).

One thing researchers have shown time and again, is that 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 without therapy.

To help develop treatments that target the cause, an international research effort is now underway to try and identify the genes that cause stuttering.

Stuttering can run in families, suggesting that genes are involved. Picture: Getty Images

Led by researchers at the Walter and Eliza Hall Institute for Medical Research, Murdoch Children’s Research Institute, Griffith University, the QIMR Berghofer Medical Research Institute and the University of Melbourne, the Genetics of Stuttering Study will be the largest ever into the condition.

Experts in Australia are currently recruiting 3,000 people aged seven and older who have ever stuttered, and the recruitment effort will be expanded internationally.

But even if you have never stuttered, you can still make life a little easier for those of us who do stutter. Here are some simple tips for speaking with someone who stutters:

  • Be patient, and listen when it’s your turn. Someone who stutters may need more time to get their message across. If there are extended pauses or repetitions, try not to speak for the other person or finish their sentences. Focus on the purpose of the interaction, rather than its pace.
  • Consider your body language and facial expression – these should be no different from any other interaction you have. Maintain eye contact and wait patiently. There is no need to be embarrassed or alarmed, show the other person that you are listening to what they are saying.
  • As a fluent speaker, refrain from giving advice on how to speak, like saying “take your time; just relax; take a deep breath; think about what you want to say”. This is not only condescending to the person stuttering, but it may lead to more anxious responses and can be disruptive and upsetting.
  • If you don’t understand what is being said, it’s okay to clarify. You might say “Sorry I missed that, can you say that again?”. Sometimes specific sentences or words may be harder to understand. As with any interaction, it’s best to clarify rather than go on pretending that you have understood.
  • Be respectful and kind, it takes two for an interaction to be a success.

Finally, remember that it’s okay for people to stutter. We all want to talk and express our thoughts or ideas. Some of us just need a bit more time.

To sign up the study please email us at or visit our website.

Banner: Getty Images