A rhythm defect in the brain: science sheds light on stuttering

New scientific evidence shows that the disorder is rooted in genetics and often hereditary, not an emotional problem

28 July 2025

3' min read

Key points

A widespread but little understood disorder
What the study reveals
A neurological, not an emotional condition
Towards new perspectives and less stigma

3' min read

In the film 'The King's Speech', which recounts the life of King George VI of the United Kingdom and his struggle with a severe stutter, his father tries in vain to help him by shouting "Relax!", as if the disorder was under his control. Science has now proven that stuttering is an involuntary condition, with a strong hereditary component, whose origin remains complex and still partially obscure.

A new study, published in Nature Genetics, sheds light on this mystery. Analysing the genetic data of 1.1 million users of the 23andMe platform, researchers identified 57 regions of the DNA never before associated with stuttering. The genes involved relate to brain functions and rhythmic abilities and show possible links to other disorders, such as autism and depression.

According to Gregory Snyder, a speech disorders expert at the University of Mississippi, the study represents a 'quantum leap' for research. The discovery could help identify the biological mechanisms underlying stuttering and, eventually, lead to new medical treatments.

A widespread but poorly understood disorder

Stuttering affects about 1% of the world's population, around 70 million people, regardless of language and origin. It often appears in childhood: many children recover spontaneously, but for others it becomes a chronic condition that requires speech therapy and coping strategies.

In the past, genetic research was limited by computing power and the size of databases. Studies focused on genetically homogeneous groups in Pakistan and Africa, identifying some mutations, but with results that were difficult to extend to the rest of the population. 'It is amazing to see how far we have progressed since then,' Snyder comments.

What the study reveals

The researchers compared the genetic profiles of 99,076 users who reported having stuttered at least once with those of nearly one million people who answered 'no'. The analysis, broken down by gender and genetic origin, led to the identification of 57 regions of the DNA that contribute modestly to the risk of stuttering, similar to complex traits such as insomnia and type 2 diabetes.

Among the most significant genes is VRK2, already associated with early neuronal development and disorders such as schizophrenia, epilepsy and multiple sclerosis, as well as difficulties in perceiving and reproducing musical rhythm. This connection strengthens the already growing hypothesis that stuttering may be linked to a deficit in rhythm perception.

Twenty other identified genes had already been linked to neurological and psychiatric conditions such as autism and Adhd, suggesting common developmental pathways.

A neurological condition, not an emotional one

For Loryn McGill, a speech therapist at the University of Southern California, these data confirm that stuttering is a neurological disorder and not an emotional or behavioural problem. McGill hopes that the finding will raise awareness among paediatricians about the heredity of stuttering: "Many minimise the problem, reassuring parents without considering family history".

The study has some limitations: the majority of participants were female, although globally men are approximately four times more affected. Furthermore, it was not possible to confirm the validity of the results for individuals of Asian and African origin due to the small number of samples.

Towards new perspectives and less stigma

Future studies could clarify which genes play a causal role in stuttering, although, as Nan Bernstein Ratner of the University of Maryland points out, 'it is unlikely that we will discover a simple "switch" to turn it off'.

The research, however, could help combat the stigma: stuttering is still perceived as a consequence of trauma or personal weakness. "We want to spread the idea that stuttering is a genetic trait, not a fault," says Jennifer Below, a geneticist at Vanderbilt University, "to help change public perception and alleviate the guilt that many people experience.