SynapDx Autism Gene Expression Analysis Study (STORY)

This study will prospectively enroll approximately 880 children, at least 18 months and less than 60 months of age, who have been referred to a pediatric developmental evaluation center. Enrolled children will have blood drawn for RNA gene expression analysis and optionally for metabolite, lipid and DNA analysis and undergo a clinical evaluation to determine the presence or absence of a diagnosis of ASD. The primary objective of this study is: \- To develop an algorithm to classify blood RNA gene expression patterns to maximize agreement between the classification and a clinical assessment of presence or absence of Autism Spectrum Disorders (ASD). The secondary objectives of this study are: * To develop an algorithm to classify plasma metabolite and/or lipid profiles in such a way as to maximize agreement between the classification and a clinical assessment of presence or absence of ASD. * To prospectively assess the clinical sensitivity and specificity of the plasma metabolite and/or lipid profile classification algorithm in a separate population consisting of children referred to a developmental evaluation clinic for a possible developmental disorder (DD). * To evaluate clinical sensitivity and specificity of various combinations of gene expression signature, metabolite and/or lipid signatures, and presence of ASD-associated genetic variation detected by chromosomal microarray analysis (CMA) or sequencing protein-coding regions of the genome.