SFA RESEARCH FALL 2019
"THERE HAVE BEEN DOZENS OF BRAIN IMAGING STUDIES INVOLVING PEOPLE WHO STUTTER, BUT THOSE RESULTS CAN ONLY TAKE US SO FAR..." - DR. DENNIS DRAYNA
“Identifying the genetic and cellular changes that underlie stuttering has helped researchers and others realize that persistent stuttering is a brain disorder,” said Andrew Griffith, M.D., Ph.D., NIDCD scientific director. “Perhaps even more importantly, understanding the cells that are involved opens opportunities for novel interventions for stuttering – and possibly other speech disorders.”
Earlier research by Drayna and colleagues to identify genes associated with stuttering laid the foundation for the new findings. By studying families from around the world in which stuttering affects several members, Drayna’s research team identified the first of several genes linked to the condition in 2010.
“There have been dozens of brain imaging studies involving people who stutter, but those results can only take us so far,” said Drayna. “By taking a genetic approach, we have been able to begin to decipher the neuropathology of stuttering, first at the molecular level by identifying genetic mutations, and now at the cellular level.” All of the stuttering genes Drayna’s team has
identified over the past decade are involved in intracellular trafficking, the process that cells use to move proteins and other components to their correct locations within the cell. Defects in cellular trafficking have been linked to other neurological disorders, such as amyotrophic lateral sclerosis (ALS), Parkinson’s disease, and Alzheimer’s disease, suggesting that certain nerve cell pathways are particularly sensitive to impairment of this process. The research does not indicate, however, that persistent stuttering is an early indicator of these other disorders.
In the current study, Drayna and his team set out to identify changes in the brain brought on by the mutations in one of the genes previously linked to stuttering. The scientists created a mouse model of stuttering by engineering a human stuttering mutation in a gene called GNPTAB into mice. The mice had long pauses in their stream of vocalizations, similar to those found in people with the same GNPTAB mutation. Like people who stutter, the mice were normal in all other ways, reinforcing earlier research that suggests that the mice can serve as a valid animal model for important features of this disorder.
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