Individuals with language impairment suffer from a wide-range of lifelong, detrimental socioeconomic consequences frequently resulting from academic under-achievement and reduced self-perception of cognitive abilities. Several behavioral disorders contain language impairment as a diagnostic basis, including dyslexia, Speech Sound Disorder (SSD), Specific Language Impairment (SLI), and Autism Spectrum Disorders (ASD). Observed co-occurrence and overlap of clinical presentation among these disorders suggest dyslexia, SSD, SLI, and ASD share determinants. Past studies have implicated the same genes and genomic areas in these various disorders. However, to what extent dyslexia, SSD, SLI, and ASD share genetic determinants remains to be evaluated. Thus, the overall goal of these investigations is to determine the shared and unique genetic determinants of dyslexia, SSD, SLI, and SSD. The hypothesis is known dyslexia genes will contribute to the observed language impairment in SSD, SLI, and ASD. Identification of these core language genes could lead to the development and implementation of interventions targeting a variety of language disorders and their core deficits. To test this hypothesis, six different cohorts will examine the contribution of dyslexia genes to language impairments in SSD, SLI, and ASD. This study plan will identify shared and unique genetic determinants of dyslexia, SSD, SLI, and ASD independently through the use of multiple epidemiological and genetic designs. Specifically, the study aims to: 1) Evaluate the contribution of dyslexia genes to SSD and SLI 2) Determine the contribution of dyslexia genes to language deficits in ASD 3) Compare and evaluate effects of genes implicated in dyslexia among cohorts Determining the specific and global effects of these genes on language will demonstrate which genes cause certain language impairments and which control core language skills. Completion of these aims will be utilized in future investigations to develop clinical tools to diagnose global and specific language deficits. Additionally, future analyses will aid in creating genetically informed interventions that target both core language deficits that disorders share and impairments specific to the affected children. PUBLIC HEALTH RELEVANCE: Children with language impairment suffer from a wide-range of lifelong social and economic consequences resulting from academic under-achievement and reduced self-perception of cognitive skills. These investigations aim to identify genes common to multiple disorders in order to permit earlier diagnoses and the use of biologically informed interventions early in life when it is most effective. Future analyses will aid in creating genetically informed interventions that target both core language deficits that disorders share and impairments specific to the affected children.