HCRI Stuttering Research on the Genetics of Stuttering

Since HCRI began in 1972, scientific discovery has been at the core of the institute’s work to advance the understanding and treatment of stuttering. While the nonprofit center is best known for its 12-day stuttering therapy, HCRI has been a leader in investigating stuttering and developing treatment innovations. The institute’s work has shaped how stuttering is viewed and treated across the U.S. and around the world.

Stuttering is one of the most misunderstood and mistreated of all human disorders, according to HCRI President Ronald L. Webster, Ph.D. “Our ongoing research focuses on increasing our knowledge of stuttering as a physical condition – and uncovering new insights for effective treatment.”

HCRI’s collaborative research on the genetics of stuttering represents a new frontier in understanding and addressing this difficult-to-treat disorder. The stuttering research below is based on HCRI’s long-standing relationship with the National Institute on Deafness and Other Communications Disorders (NIDCD); in particular, the genetics research project headed by Dr. Dennis Drayna. Dr. Drayna is Section Chief of Genetics of Communication Disorders at the NIDCD.

HCRI's Genetic Research Initiatives

Discovery of Genetic Link to Stuttering

HCRI was a member of the NIDCD team that discovered three mutant genes that are linked to stuttering. These genes were found to be heritable within selected family groups. The genes deal with mechanisms that break down and recycle waste materials within cells that reside within key regions of the brain. This stuttering research served as the first step in identifying genes that play a role in stuttering – and set the stage for subsequent genetic studies. This work further calls attention to the physical mechanisms that are likely to play a causative role in stuttered speech.

  • Published in the February 10, 2010 issue of the New England Journal of Medicine. Read the Study.

Stuttering and Mucolipidosis are Associated with Different Variants in the Same Genes

This initiative, conducted in partnership with HCRI and NIDCD, the Laboratory of Communications Disorders, and Porter Neuroscience Research Center, studied the same genes that are linked to stuttering and mucolipidosis II and III. Mucolipidosis is a progressive disorder, characterized by growth retardation, skeletal abnormalities, facial dysmorphism, developmental delays, and heart issues. Finding revealed that, while the genes are the same, the genetic variations for mucolipidosis are different than the genetic variations for stuttering.

  • Published in the July 15, 2015 issue of the European Journal of Human Genetics. Read the Study.

Effect of Mutant Genes on Stuttering Therapy

HCRI participated with the NIDCD in the first study to evaluate stuttering therapy outcomes among a group of stutterers who possess one of the mutant genes for stuttering compared to a group of stutterers who do not carry the same mutant genes. HCRI was selected for the study because of the institute’s objective, physically based approach, as well as the large number of clients successfully treated. More than 10,000 hours of HCRI therapy were involved in this stuttering research initiative. The study found that HCRI therapy was effective with both groups. However, the group of mutant-gene carriers had more self-reported issues with struggle, avoidance and expectancy when speaking.

  • Published in the July/August 2019 issue of the Journal of Communications Disorders. Read the study

Based on the findings of this study, Dr. Webster points out the need to further investigate the physical details of speech among mutant-gene carriers. Subsequent to publication of the therapy report, HCRI research has suggested the possibility that the carrier group made more small errors in the production of fluency skills than the noncarriers. Additional study will enable the HCRI team to more precisely define the effects of therapy within this group. It may also set the stage for customizing treatment for individuals who carry mutant genes. The institute is pushing forward on the search for those physical mechanisms that cause stuttering.

“From our basic research to our effective, evidence-based therapy, everything we do at HCRI is centered on helping individuals who stutter achieve a lifetime of fluency. And, that’s precisely why we are here,” Dr. Webster added.

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