Dennis Drayna, Ph.D., has served on the Stuttering Foundation Board of Directors since 2006. He is senior investigator at the National Institute on Deafness and Other Communication Disorders, National Institutes of Health.
His current research focuses on using genetic methods to identify the underlying causes of stuttering.
“Stuttering is a remarkably difficult disorder to study. It only occurs in awake, behaving humans that are otherwise normal, and it likely has its origins in the brain, which is inaccessible for direct studies,” Drayna explained. “ The fact that genetics plays a role in stuttering gives us one of the few avenues available to study this disorder, with the advantage that genetic studies can lead us to the cells and molecules that are involved.”
Studies to date have identified mutations in three related genes, named GNPTAB, GNPTG, and NAGPA that explain approximately 10% of familial stuttering. Several lines of investigation are being pursued to discover exactly how these variant genes lead to stuttering. In one line, biochemical studies of the enzymes encoded by these genes show that the mutations lead to a partial loss of enzyme function, apparently enough to cause some sort of damage to a particular set of nerve cells in the brain, but not so much as to cause more severe symptoms.
In another line of investigation, Dr. Drayna and other researchers are studying which cells within the human brain express (or “turn on”) these 3 genes at the highest levels, as such cells are good candidates for the ones that are damaged or otherwise impaired by these mutations.
In yet another line of investigation, Dr. Drayna and his co-researchers are putting these mutations into mice and measuring their vocalizations (which are largely ultrasonic), in an effort to develop a mouse model of stuttering that could be used for a wide variety of studies.
“When I started research on stuttering in 1996, my goal was to bring this disorder into the larger world of biomedical research,” Drayna said. “I had a strong prejudice that it was a biological disorder, rather than a psychological or social disorder. We’ve been fortunate to identify several causative genes that reinforce this view, although we still have a long way to go to explain all of stuttering.”
Other studies in stuttering families are identifying the location of additional genes that cause stuttering, the identification of which will hopefully provide insights into the cause of stuttering in the wider population.
“One of the biggest influences on my thinking has come from getting to know the stuttering community. This has allowed me to see the impact of stuttering on people’s daily lives,” Drayna said. “It’s allowed me to realize the seriousness of the disorder, and to advocate for a state-of-the-art biomedical research program to address it.”
Drayna received his bachelor’s degree in Genetics from the University of Wisconsin in 1976. He later earned a Ph.D. in genetics from Harvard University in 1981. His postdoctoral fellowship took place at the Howard Hughes Medical Institute, University of Utah, from 1981 through 1985.
From 1985-1992, he worked as a scientist for Genentech. He later founded Mercator Genetics Inc., where he worked as the scientific director until he joined the National Institute on Deafness and Other Communication Disorders in 1992.
“Science can be a maddeningly slow and uncertain process, with many blind alleys and precious few successes,” Drayna said. “In addition, understanding the underlying causes of stuttering can be a long way away from new, more effective treatments for the disorder. But without research, we’re left with speculation and misunderstanding. The cause of stuttering deserves better.”
-From the Winter 2012 Newsletter
Dr. Drayna serves as part of his personal commitment to helping those who stutter, and not in his official duty as a scientist at the National Institutes of Health.