With appropriate intervention, the clinical course of children with PWS can be changed for the better. Individuals who have had the benefit of early diagnosis and treatment will have more normal (although generally still excessive) weight, less severe short stature, less persistent hypotonia, and significantly improved mobility and activity than would otherwise be possible. With proper care, the behavior problems, while significant, are manageable. The expected lifespan of individuals with PWS who have received anticipatory care and appropriate attention to medical problems has yet to be determined but can be beyond 30 to 40 years and can be associated with an absence of the related major comorbidities and a markedly improved quality of life.