The diagnosis of Prader-Willi syndrome (PWS) is based on clinical findings that change with
age. Hypotonia is prominent in infancy. Obesity, mild mental retardation or learning
disability, and behavior problems, especially in association with food and eating result in a
debilitating physical and developmental disability in adolescence and adulthood. No
consistent biological marker is yet available for PWS in spite of recent research activity in
cytogenetics and molecular genetics. Diagnostic criteria for PWS were developed by …