According to the National Institute on Deafness and Other Communications Disorders, ‘stuttering is a speech disorder characterized by repetition of sounds, syllables, or words; prolongation of sounds; and interruptions in speech known as blocks.’ The website also shares that around 3 million Americans of varying ages suffer from stuttering.
Normally arising very early in childhood, this chronic condition usually negatively affects those diagnosed with it, from their education to their job performance, and even their employability as they enter into adulthood.
Unfortunately there is no known cure for stuttering, and the existing treatments tend to be minimally effective as well. But for those that have persistent, developmental stuttering, new groundbreaking research is providing new hope.
This revolutionary research was led by scientists from Vanderbilt University Medical Center in Nashville, Tennessee, as well as Wayne State University located in Detroit, Michigan.
Two papers were published recently by Jennifer “Piper” Below, Ph.D. and Shelly Jo Kraft, Ph.D., who describe what they call “genetic architecture” for developmental stuttering and report ‘the discovery of new genetic variations associated with the condition.’
For the research group, they explained that their findings and other studies like them ‘have the potential to identify therapeutic directions that could possibly improve the outcomes for people that are dealing with stuttering.
Below, who also happens to be an associate professor of Medicine at VUMC, explains that “It’s clear that in populations, stuttering is polygenic, meaning that there are multiple different genetic factors contributing to and protecting people from risk. That was something that had not been clearly shown before these studies.”
As predicted by Kraft, who happens to be an associate professor of Communication Sciences and Disorders and director of the Behavior, Speech & Genetics Lab at Wayne State University, she explains that these new findings will surely impact on those who stutter, as well as the parents of the children that also have the condition.
She shared, “It’s a piece of themselves that they can then understand instead of living a lifetime of experiencing this difference in their speech and never knowing why.”
Gathering help from her colleagues in England, Australia, Ireland, Sweden, Israel, and across the United States, Kraft took blood and saliva samples to use for genetic studies from over 1,800 people that stutter, which included 250 families with three generations of stuttering as well.
These efforts, which was named International Stuttering Project, managed to identify new genetic variations or variants that have been associated with developmental stuttering, but it was also no sufficiently “powered” to show the true complexity of the condition. There just weren’t enough participants included in the studies conducted.
But when Below joined the efforts, she utilized a key VUMC resource, which is BioVU, considered one of the world’s biggest repositories of human DNA that’s linked to searchable, electronic health information. BioVU is what enables researchers to conduct genome-wide association studies, or GWAS, to explore the ‘genetic underpinnings of a wide range of diseases.’
When it comes to stuttering though, it isn’t mentioned much or given a diagnostic code when it comes to someone’s medical records. People don’t get hospitalized for stuttering, which is why Below explains, “We had to come up with some clever new ways to try to capture that missing code.”
It was from confirmed cases of developmental stuttering that researchers were able to construct a “constellation” of diagnostic codes for other conditions like attention-deficit hyperactivity disorder (ADHD) and autoimmune reactions to infections that co-occur with stuttering more than they would be expected to happen by chance.
Using machine learning techniques, the research group produced an artificial intelligence tool that took into account the presence of these “phenotypes” that were recorded in the electronic health record to predict who would possibly stutter “even in the absence of having a direct note about their stuttering in their medical record,” explains Below.
The five-year grant, which was awarded to the group in 208 by the National Institute on Deafness and Other Communication Disorders, which is part of the National Institutes of Health, provided $3.5 million for their studies. And through their research, they were able to demonstrate that their stuttering prediction model ‘positively predicted the presence of stuttering more than 80% of the time.’
Published in The American Journal of Human Genetics, the research also managed to find a stuttering-related gene that is normally implicated in the autism-spectrum disorder, as well as the genetic variants that may affect the regulation of sex hormones. Meanwhile, the latter findings could also help explain why boys have a higher rate of being diagnosed with stuttering than girls, as well as why women are more likely to recover from stuttering than men.
Below also noted that some correlations between traits could be bogus. But if the researchers manage to establish genetic connections between stuttering and other types of conditions like ADHD, Kraft hopes that these findings could potentially broaden the channels of treatments for both of these conditions simultaneously.
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