Smith-Magenis Syndrome (SMS) is characterized by facial dysmorphism, behavioral problems, sleep disturbances, growth retardation and moderate mental retardation. Brachycephaly, mid-facial hypoplasia with broad flat midface, broad nasal bridge, and prognathism are classical facial features. Cognitive, psychomotor, and speech delays are common. Neurobehavioral features become more pronounced with age and can include hyperactivity, temper tantrums, attention-seeking, self-hugging, self-injurious behaviors, and sleep disturbances. About 40% of patients with the 17p11.2 deletion have structural or functional congenital heart defects. Hoarse voice, hearing loss, and eye abnormalities are frequently present as well. Hypercholesterolemia has been reported in 70% of affected patients.