ABSTRACT
Prader–Willi syndrome (PWS) is a complex disorder with cardinal features of infantile hypotonia, mental deficiency, hypogonadism, early onset of childhood obesity, small hands and feet, short stature and a characteristic facial appearance. Features of PWS were first described in an adolescent female by Down in 1887. Genomic imprinting appears important for growth in humans and other mammals. Many conditions are thought to be due to imprinting and present with either overgrowth or growth retardation. Many clinical features in PWS may be subtle or nonspecific, whereas other features are more characteristic. The primary features of PWS include infantile hypotonia, feeding difficulties, mental deficiency, hypogonadism, behavior problems, hyperphagia and early onset of childhood obesity, small hands and feet, endocrine disturbances including growth hormone deficiency and a characteristic facial appearance. Obesity is the most significant health problem in PWS and an increasingly common trait found in about one-half of the US adult population.
