Project Summary/Abstract Language difficulties have been reported in nearly 70% of people with tuberous sclerosis complex (TSC), but language development is poorly understood in this population. Further, 50% of individuals with TSC develop autism spectrum disorder (ASD); language deficits are also common in ASD. In a preliminary study, we found deficits in early vocal development in most infants with TSC regardless of the diagnosis of ASD. Thus, the goal of our current proposal is to examine potential predictors of language outcome and ASD severity in infants with TSC. In Aim 1, we will code audio-video recordings of infants from TACERN (Tuberous Sclerosis Autism Center of Excellence) for canonical babbling (a precursor to language) and volubility. We will compare canonical babbling and volubility to a non-vocal measure, shared attention, in predicting language outcome and ASD severity at 12 months as measured by the Early Social Communication Scales (ESCS). Aims 2-4 will entail a new longitudinal study of the trajectory of language development and predictors of language outcome and ASD severity. Language will be measured using LENA (Language ENvironment Analysis) recordings (Aim 2); a fast-mapping paradigm (Aim 3) and the MacArthur-Bates Communicative Development Inventories (MCDI) (Aim 3). Shared attention will be measured using the ESCS (Aim 2). Each measure will generate potential predictors of outcome. We will examine how these measures predict language outcome as assessed by the Preschool Language Scale 5 (PLS-5) (Aims 2-3) and autism severity as measured by the Autism Diagnostic Observation Schedule (ADOS) at 36 months (Aim 4). Currently, despite the high risk of language difficulties and ASD in TSC, very little to no data are available about the origin and trajectory of language in TSC and how this might predict outcome. Data generated under this Award will serve as the foundation of an independent research program dedicated to the intersection of TSC neurobiology and language development.