Genetic Etiology of Developmental Stuttering

Abstract

Despite a 1% prevalence of stuttering in the general adult population, developmental stuttering, characterized by blocks, repetitions, and prolongation of sounds in speech with a childhood onset, persists as a largely idiopathic speech fluency disorder. Stuttering has been observed since antiquity, yet it is still poorly understood, leading to stigma and a paucity of efficacious treatments for adults. Twin studies demonstrate the high heritability of developmental stuttering (50%-80%); nevertheless, prior familial studies and studies of population isolates have failed to elucidate the genetic etiology of developmental stuttering, particularly at a population-level. The research presented here utilizes biobank data, a clinically ascertained global stuttering sample cohort, and an exceptionally well-powered self-report stuttering sample to show how developmental stuttering risk is driven by genetic effects detectable at both the familial and population-level. Our research reveals that stuttering is a complex and polygenic trait. This work informs our understanding of the molecular etiology of stuttering by detailing how genetic variation regulates vital endocrine and neurological systems to impact stuttering risk. Additionally, novel research into known and newly uncovered stuttering comorbidities identified shared genetic liability between stuttering and some of its behavioral comorbidities and associated endocrine traits. The remarkable advances in characterizing the genetic basis of stuttering presented herein lay groundwork that will shape how stuttering is perceived and managed, with the potential to enhance patient care. Moreover, public awareness of the genetic causes of stuttering may dispel myths about stuttering and alleviate feelings of shame experienced by some individuals who stutter and their families. Furthermore, our studies begin to unravel the molecular forces that result in speech and language generally and ultimately coalesce to enable communication.