Prader-Willi syndrome is considered to be one of the extremely rare genetic diseases. The disease is characterised by the appearance of a number of characteristic clinical symptoms. According to statistics, it is estimated that Prader-Willi syndrome affects one in twenty thousand babies born. What are the characteristics of the disease? What is the course of treatment? Can the disease be detected by a simple laboratory test? How can a sick child be helped? Where can one look for help?