Prader-Willi syndrome is a multi-faceted and genetically-determined syndrome. The two main genetic causes and other rarer cause of PWS all involving chromosome 15 give rise to a pattern of atypical early development characterised by extreme floppiness and failure to thrive at birth with the subsequent emergence of severe over-eating and the risk of severe obesity if access to food is not controlled and also to other difficult behaviours, and the presence of learning disabilities, hormonal deficiencies, and specific physical characteristics. With knowledge and careful management and support the person with PWS can live a happy and well-adjusted life within the parameters of the syndrome. IPWSO strives to offer best international practices for care and information on the syndrome. If you need support of any kind, please contact us.