Heterozygous disruptions of FOXP2 were the first identified molecular cause for severe speech disorder; childhood apraxia of speech (CAS), yet few cases have been reported. We phenotyped 28 individuals from 17 families with pathogenic FOXP2-only variants. Speech disorders were prevalent into adulthood; with CAS the most common diagnosis. Cognition (average to mildly impaired) was incongruent with language ability (average to severely impaired). There was an increased prevalence of anxiety, depression, and sleep disturbance, but FOXP2 dysfunction remains relatively specific to speech disorder. Thus, we reinforce that FOXP2 provides a valuable entry point for examining the neurobiological bases of speech disorder. (By Lottie Morison, https://jmg.bmj.com/content/early/2022/11/03/jmg-2022-108734 )