Stuttering is a disorder of the flow of speech characterized by involuntary repetitions or prolongations of sounds or syllables, and by interruptions of speech known as blocks (summary by Raza et al., 2010). Stuttering typically arises in young ... Stuttering is a disorder of the flow of speech characterized by involuntary repetitions or prolongations of sounds or syllables, and by interruptions of speech known as blocks (summary by Raza et al., 2010). Stuttering typically arises in young children, where it affects at least 15% of those in age range 4 to 6 years (Bloodstein, 1995). Stuttering usually resolves spontaneously before adolescence, leading to a population prevalence of 1 to 2% among adults. Stuttering beyond childhood is characterized by a significant bias towards males, with males outnumbering females by a ratio of 3:1 to 5:1 (Yairi et al., 1996). - Genetic Heterogeneity of Familial Persistent Stuttering STUT1 maps to chromosome 18q; STUT2 (609261) maps to chromosome 12q24; STUT3 (614655) maps to chromosome 3q; and STUT4 (614668) maps to chromosome 16q.