[Prader-Willi syndrome].

In the multifactorial aetiology of childhood obesity, Prader-Willi syndrome (PWS), probably is the commonest cause of abnormal overweight. The estimated prevalence of which is 1 in 10,000-25,000. Most of the approximately 75 known cases in Norway concern patients under 20 years of age. Recent years have witnessed a marked increase in our knowledge of the genetic aspects of PWS. Treatment needs to be multidisciplinary in approach, and to be started early to forestall a number of organic complications associated with reduced appetite control and significant overweight.