Growth hormone treatment in children with prader-willi syndrome : Three years of longitudinal data in prepubertal children and adult height data from the KIGS database

__Abstract__ This is the fifth thesis of our research group in the field of Prader-Willi syndrome (PWS) and encompasses 6 new studies embedded in the Dutch PWS Cohort study in children and adolescents with PWS. In 1887, sir Langdon Down described an adolescent girl with short stature, obesity, hypogonadism and cognitive impairment. Almost a century later, in 1956, 3 endocrinologists Prader, Labhart and Willi described the most characteristic features as “Ein Syndrom von Adipositas, Kleinwuchs, Kryptorchidismus und Oligophrenie nach myotoniertigem Zustand im Neugeborenenalter”. A detailed description of the syndrome was given several years later. The clinical features which were considered characteristic were floppy at birth, obesity, mental retardation, hypogonadism, hypotonia, shortness of stature, prominent forehead, almond-shaped eyes, retrousse nose, small fish-like mouth, short hands and feet and some of them showed a diabetic type of glucose tolerance test. First research topics were predominantly describing the syndrome, at that time also known as syndrome of Hypotonia-Hypomentia-Hypogonadism-Obesity (HHHO), and focused on the relations with diabetes and the cause of hypotonia. In the 70s studies reported on low growth hormone (GH) levels9-11 and the first clinical trial with GH treatment was published in the 80s. Since 2002, our research group has been investigating the effects of GH treatment in children with PWS in the Dutch PWS Cohort study. Knowledge about different aspects of PWS has vastly increased over the past 50 years, although new questions and dilemmas are met and need further investigations. This chapter describes the clinical manifestations in different stages of life, the genetic background, the hypothalamic – pituitary axis in children with PWS. In the scope of this thesis, characteristics of children with PWS are described in combination with the longterm effects of GH treatment. Finally, the aims of the studies described in the following chapters are presented.