“Our results indicate that carrying a mutation in one of the known stuttering genes can affect therapy outcomes” – Frigerio-Domingues et al 2019
There is extensive research that shows genes play a role in developmental stuttering. Specifically, 4 genes have been identified to be associated with stuttering: GNPTAB, GNPTG, NAGPA and AP4E1. See Genetics of Stuttering for more details.
This study compared the treatment outcomes for people with genetic differences (known to be associated with stuttering) to those with no associated genetic mutations.
Why is this important?
Wouldn’t it be nice to know the likely success of a particular treatment program before starting it? This information may help an individual make a decision about whether or not to participate in a specific program, and also have realistic expectations.
There are several treatment approaches that are available to people who stutter, but we know little about how different people respond to these programs.
What treatment did this study look at?
This study examined an intense 12 day “fluency shaping” treatment program. This program aimed to teach people who stutter how to speak more fluently by changing the way they speak. This differs from behavioural treatment programs, which address cognitive factors and anxiety, such as the Lidcombe program.
This study included 51 people with mutations in one of the 4 genes known to be associated with stuttering. Outcomes from these individuals were compared to those from 51 people who stuttered but did not have any (known) related genetic mutations.
Was there a difference?
Overall, the therapy improved the fluency of both those with and without a genetic mutation.
On the self perception scale, there was a significant difference between those who did and did not have the genetic mutation. Those with the genetic mutation had significantly less resolution of stuttering symptoms.
From the speech pathologist’s ratings, those with the mutation had less resolution than those without the mutation, but this difference was not significant (from statistical tests).
This study provides some evidence that genes may influence fluency shaping treatment outcomes. But we need a lot more research before we can be sure of these findings.
Frigerio-Domingues, C. E., Gkalitsiou, Z., Zezinka, A., Sainz, E., Gutierrez, J., Byrd, C., Webster, R., Drayna, D. (2019). Genetic factors and therapy outcomes in persistent developmental stuttering. Journal of Communication Disorders, 88, 11-17, doi: 10.1016/j.jcomdis.2019.03.007