This study presents data from two families with high incidence of stuttering, comparing methods of phenotype assignment and exploring the presence of other fluency disorders and corresponding speech characteristics. Three methods for assigning phenotype of stuttering were used: self-identification, family identification, and expert identification. Agreement on which individuals were assigned by each of these methods was studied. Multiple measures of fluency and speech production were obtained. Some families with high incidence of stuttering may also have high incidence of other fluency disorders and other speech production difficulties. The authors suggested this finding may have ramifications for genetic studies, including criteria for defining phenotype and collapsing data across multiple families.
Stager, Shelia V., Freeman, Frances J., and Braun, Allen. (2015). Characteristics of Fluency and Speech in Two Families with High Incidences of Stuttering. Journal of Speech, Language, and Hearing Research. doi:10.1044/2015_JSLHR-S-14-0080