For those who stutter, a simple conversation can be a frustrating experience.
The mechanism that underlies stammering is unclear, although a telltale genetic mutation was recently pinpointed as the culprit. How this mutation causes fits and starts in speech is unknown, but researchers from Washington University say they have taken an important step toward building a genetic understanding of stuttering.
The Stammering Gene
The researchers worked with a mutation in a gene that is known to cause stuttering in humans. The gene, called Gnpatb, is normally responsible for clearing waste materials out of our cells. Other mutations in the Gnpatb gene can cause rare but destructive diseases related to a build-up of harmful material in cells, but one specific kind of mutation did something very different.
The researchers inserted the stuttering mutation into young mice for this study, because they are known to emit consistent ultrasonic vocalizations when separated from their mothers. Compared to mice without the mutation, the altered mice displayed unique patterns of vocalization that was structurally similar to stuttering in humans — they had trouble vocalizing quickly, and often repeated sounds.
Human stutterers can pronounce just as many words and sentences as everyone else, but have trouble properly vocalizing fluid strings of syllables. Mice exhibited the same difficulty with stringing together “phrases” while maintaining other aspects of speech, such as the pitch, variety and amplitude of their squeaks. Therefore, researchers believe, mice may serve as an ideal model for studying stuttering in humans. They published their results Thursday in the journal Cell.
Currently, there is no cure for stuttering, and this study is a small step toward that goal.
Behavioral approaches, such as speech therapy, can work in some cases. And for many children, stuttering disappears over time without intervention. But, in severe cases, a method that specifically targets the relevant area of the genome could be helpful.
Now that researchers have evidence that mice respond to the stuttering gene similarly to humans, they plan to test various drugs and procedures to see if they smooth out speech. And because the mechanism behind stuttering works the same in mice and humans, there’s a higher chance that a cure in mice will translate to humans.