 Dietary cholesterol supplementation in children with SLOS is reported to improve behavior, growth and nutritional status. Based upon observational studies, the behavioral changes reported with dietary cholesterol supplementation occur rapidly and appear to be reversible. Parental reports of improved behavior could be influenced by a placebo effect. Thus, we are proposing a blinded study to compare behavioral changes while the patient is on cholesterol supplementation egg yolk versus no cholesterol supplementation egg substitute. 