For the TD participants, these children will be recruited in several ways including using social media through Arkansas Children's Hospital, flyers posted in the community (i.e. primary pediatric clinics), as well as referrals from pediatricians. 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.