PRADER-WILLI-SYNDROME AND THE HYPOTHALAMUS

Dysfunction of various hypothalamic systems may be the basis of a numb er of symptoms in Prader-Willi syndrome. The often abnormal position o f the baby in the uterus at the onset of labour, the high percentage o f infants with asphyxia and the high proportion of children born prema turely or post-maturely may all be related to abnormal fetal hypothala mic systems, as the fetal hypothalamus plays a crucial role in labour. Abnormal luteinizing hormone-releasing hormone neurones are thought t o be responsible for the decreased levels of sex hormones, resulting i n non-descended testes, undersized sex organs and insufficient growth during puberty. A lack of growth hormone-releasing hormone may also co ntribute to the short stature of patients with Prader-Willi syndrome. In addition, the aberrant control of body temperature and daytime hype rsomnolence may result from hypothalamic disturbances. The number of o xytocin neurones - the putative satiety neurones - in the hypothalamic paraventricular nucleus is markedly decreased in Prader-Willi syndrom e. This is presumed to be the basis of the insatiable hunger and obesi ty of patients with the syndrome.