[Prader-Willi syndrome in 2015].

Prader-Willi syndrome is a neurodevelopmental disorder caused by the lack of expression of imprinted genes of the chromosomal region 15q11-q12. Diagnosis can now be made in the first months of life, allowing a precise description of the natural history of the disease. Of interest, nutritional phases appear to be more complex than those initially reported, starting with a severe hypotonia with deficit of suckling and failure to thrive in neonates, and subsequently switching to excessive weight gain with morbid obesity due to hyperphagia and deficit of satiety. The phenotype also includes endocrine dysfunction, intellectual disability, learning deficits, behavioural troubles with impaired social skills and psychiatric features. Multidisciplinary care has been strongly improved by the rare disease programme launched in France in 2004 and the Obesity programme in 2011 in link with the patient association. New therapeutic perspectives have arisen from knowledge of the pathophysiology of PWS.