Children with ASD with and without MD will be identified in the autism multispecialty clinic (AMC), as well as the ATN and other medical clinics that evaluate children with ASD in outpatient clinics in Arkansas. When a child is identified, the study coordinator will contact the parents and describe the study. If the parents are interested, the coordinator will screen by asking inclusion/exclusion criteria questions. If the child qualifies, the coordinator will schedule the visit and mail consent forms to the parents for their review. During the visit they will undergo a blood draw for metabolic testing. The child will then be sent to breakfast since the blood tests require collection prior to breakfast. After breakfast the participant will undergo further language and behavioral assessment while the parent will be interviewed for the Vineland and other questionnaires. The parents will be provided questionnaires for the teacher to fill out and mail in an addressed, postage paid envelope.