Autism spectrum disorder (ASD) is a common neurocognitive defect found in children. Patients with Smith-Lemli-Opitz syndrome (SLOS) have a defect in cholesterol synthesis. The majority of patients with SLOS have autistic symptoms. Researchers in this study have evaluated a cohort of ASD patients for SLOS. Although no SLOS patients were identified, a higher than expected number of children with ASD had hypocholesterolemia. The next research goal is to see if cholesterol levels can be used to define an endophenotype of ASD to identify the genetic cause of ASD in a subset of ASD patients. This will be done by exome/genome sequencing. Also underway is a clinical trial to determine if ASD patients with low cholesterol will respond to dietary cholesterol supplementation.