Cholesterol in ASD: Characterization and Treatment

Background: \- Autism spectrum disorders (ASD) are developmental disabilities characterized by impaired social interaction and repetitive and/or stereotypical behaviors. Research studies suggest that some individuals with ASD have very low blood cholesterol levels. This low cholesterol level and other abnormal sterol levels may be important markers for subtypes of ASD. Providing additional cholesterol to the diets of children with ASD may help improve behavior. \- These findings will guide the medical community in identifying individuals who should be tested for sterol disorders. This study will also help researchers learn whether adding extra cholesterol to the diet will improve behavioral and other autism spectrum characteristics seen in individuals with ASD and low cholesterol. Objectives: * To determine cholesterol levels in children with autism spectrum disorders. * To compare behavioral and other characteristics among children who have autism spectrum disorders and high, low, or normal cholesterol levels. * To determine whether adding cholesterol to the diet will improve behavioral and other characteristics in individuals with ASD and low cholesterol. Eligibility: \- Children between the ages of 4 and 12 who have been diagnosed with an autism spectrum disorder. Design: * Initial screening study will involve a collection of blood samples (for study purposes and cholesterol testing). * Children who have low cholesterol levels will take part in a study in which they will receive either cholesterol supplementation or a placebo, and will have detailed physical and psychological examinations to measure possible improvement in behavioral or other characteristics. * Children who have high or normal cholesterol levels will have further blood samples taken, and will undergo an additional set of examinations for comparison purposes. * Researchers may request blood or DNA samples from other family members (parents or siblings), which will be collected through blo