In recent years dramatic progress has been made in understanding the pathophysiology of pituitary diseases by a combination of experimental studies, molecular genetics and clinical research. This book presents an updated overview of normal and pathological hypothalamic-pituitary development. Several chapters include experimental data and describe brain and facial defects associated with various conditions of pituitary insufficiency. A major part is devoted to the still increasing number of molecular and genetic defects which are responsible for various clinical presentations of pituitary insufficiency: diseases due to genetic defects of growth hormone, TSH, gonadotropins and corticotropin secretion are extensively described. These diseases present as metabolic (diabetes insipidus and adrenal insufficiency), growth and reproductive (including puberty) disorders. A distinct chapter emphasizes the contribution of a multidisciplinary comprehensive approach including the most recent molecular and genetic tools. Finally in most chapters an effort was made to address phenotypic and genotypic presentations in affected patients including valuable information provided by magnetic resonance imaging of the pituitary and brain. This book will help endocrinologists and pediatricians by providing unique models of genetic and developmental defects of the pituitary region which bear ultimate consequences on metabolic control, growth and reproduction.