Those who stutter often suffer from considerable social restrictions. Now researchers have identified with a genome -wide association study 48 genes that are connected to stuttering. The results indicate a genetic context to other diseases such as autism and depression. A gene that is responsible for the feeling of rhythm also typically has variations in stuttering people. The new findings can help reduce the stigmatization of those affected. They could also contribute to the development of new therapeutic approaches.
With more than 400 million affected people worldwide, stuttering is the most common language flow disorder. Typical forms are syllable and word repetitions, sound extensions and breaks between the words. Most of the time the disorder aged two to five years occurs for the first time, with the problem of 80 percent of children spontaneously or accompanied by speech therapy. In some cases, however, stuttering remains until youth and adulthood, especially in men. Although it is already known that stuttering can be inherited, the causes are still largely unclear.
Genetic risk factors on the trail
“Nobody really understands why someone is stuttering; it is a complete mystery. And this applies to most language and speech disorders. They are very under research because they don’t take anyone to the hospital, but they can have enormous effects on the quality of life of those affected,” says Jennifer Below from Vanderbilt University in Tennessee. “We have to understand the risk factors for language and speech disorders so that we can recognize them at an early stage in children and those who want it to treat them appropriately.” Together with a team around first author Hannah Polikowsky, Below has therefore analyzed the genetic data of almost 100,000 stuttering and more than one million control persons.
The researchers identified 57 positions on 48 genes that have been changed in stuttering people. Based on two independent cohorts, the team confirmed that the genetic variations in these areas actually have an increased risk of stuttering. “For centuries there have been false ideas about what stuttered – from left -handing to childhood trauma to over -caring mothers,” says Below. “Our study shows that stuttering is not caused by personal or family failures or intelligence, but is influenced by our genes.”
Connection with rhythm and musicality
Among the identified genes are some that are also involved in other diseases in previous studies, including autism and depression. Since men are more often affected by stuttering than women until adulthood, the researchers examined the genetic data separately even according to gender. They found that stuttering men typically changed a gene called VRK2 that was previously associated with our sense of rhythm. According to previous studies, variations in this gene can lead to affected difficulties in clapping in time.
“In the past, we viewed musicality, language and speak as three separate units, but these studies indicate that there could be a common genetic basis. The architecture of the brain, which controls our musicality, speaking and our language, could be part of a common path,” says Below. “It is incredibly exciting to understand at a biochemical, molecular and cellular level what defines us as a species – our communication skills. We hope that this will stimulate further studies on this gene and its function in the brain.”
Her colleague and co-author Dillon Pruett, who stutters himself, adds: “There are many unanswered questions about stuttering, and as someone who is personally affected, I wanted to make a contribution to this research. Our study showed that there are many genes that ultimately contribute to stuttering risk, and we hope to be able to use this knowledge in connection with stuttering and hopefully new to develop therapeutic approaches. “
Source: Hannah Polikowsky (Vanderbilt University Medical Center, Nashville, TN, USA) et al., Nature Genetics, DOI: 10.1038/S41588-02267-2
