A global study has identified the DNA markers for stuttering, providing a genetic link that will pave the way for clinicians to predict which family members will experience the speech disorder affecting more than 400 million people worldwide.
The new research, published in Nature Genetics, has confirmed the hereditary link after one million people across the globe provided saliva samples, including 1380 samples provided by multi-generational Western Australian families through the Curtin Stuttering Treatment Clinic in collaboration with Wayne State University in Detroit.
The study -- the largest genetic analysis of stuttering -- uncovered 48 genes associated with stuttering and 57 associated genomic hotspots as well as finding a genetic link between stuttering and neurodiversity, emotional regulation and musical rhythm, suggesting a neurological basis for stuttering.
Co-author Associate Professor Janet Beilby, the Founder of the Curtin Stuttering Treatment Clinic in the Curtin School of Allied Health, said the research was groundbreaking for the millions of families affected by this common speech condition.
Associate Professor Beilby's own research -- along with other authors of this Nature publication Dr. Emily Lowther and Ms Kathy Viljoen, also from the Curtin School of Allied Health -- has demonstrated that stuttering can impact the family and every part of the child's life into adulthood.
"This finding is life-changing for all those children who stutter. Stuttering is more than just a stutter -- most children with a speech or language disorder (most notably a stutter) will be bullied at school and adults who stutter may face challenges in the workplace that can negatively affect their mental health and social well-being," Associate Professor Beilby said.
"Based on what we've found in this research, we will be able to take a DNA sample and predict if the individual is likely to stutter or not. If we can identify who in a particular family will develop a stutter, we can intervene earlier to prevent the potentially life-long consequences of stuttering that many people experience."
10-year-old Harriet Hewitt, the fourth-generation member of her family to stutter, took part in the global study with every generation up to her great-grandfather providing saliva samples to help map the genetic link.10-year-old Harriet Hewitt, the fourth-generation member of her family to stutter, took part in the global study with every generation up to her Great-Grandfather providing saliva samples to help map the genetic link. Credit: Curtin University.
Her mother, Simone, said three of her five children experienced stuttering and she was blown away by what the study had found.
"Early intervention makes all the difference when you're dealing with stuttering and I have seen that with my own children," Mrs. Hewitt said. "Harriet is a bright and bubbly 10-year-old now but when she first started stuttering, she would just go quiet.
"She has worked so hard with the amazing people at the Curtin Stuttering Treatment Clinic to find her beautiful voice that now if she stutters, it won't stop her. This research finding will be a game-changer for my own grandchildren who won't have to wait until the issue presents to get the support they need. I can't explain how much of a difference this would make to families like my own."
Developmental stuttering is the most common fluency disorder with more than 400 million people affected worldwide and a lifetime prevalence of five to eight percent among global populations with a higher prevalence in Australia -- up to 11%.
Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. Sign up for our free newsletter and get updates on breakthroughs, innovations, and research that matter -- daily or weekly.
Stuttering is a speech disorder characterized by repetitions, prolongations, and unnatural pauses in the flow of the person's speech. It typically emerges in early childhood, most commonly around the ages of two to four years.
This ground-breaking research was conducted at the Curtin Stuttering Treatment Clinic in collaboration with Dr. Shelly Jo Kraft from Wayne State University, as well as researchers from Vanderbilt University Medical Center, the University of Texas MD Anderson Cancer Center, and the University of North Carolina.
The breakthrough comes as the Curtin Stuttering Treatment Clinic, founded by Associate Professor Beilby following her own family's experience with stuttering, celebrates its 40-year anniversary this year.
The largest stuttering treatment facility in Western Australia, the Curtin Stuttering Treatment Clinic offers services to people of all ages for the management of stuttering and fluency disorders, carving out an international reputation for research into new treatment approaches.