Genetic defects of the growth hormone-insulin-like growth factor axis.

Our understanding of the physiology of the growth hormone-insulin-like growth factor (GH-IGF) axis has been characterized by remarkable advances in the past decade, with clarification of genetic defects in the development of somatotropes, GH secretion and action, and IGF synthesis and action. Combined efforts of research in this area and the development of animal models of growth retardation have also indicated new genetic abnormalities that might prove to cause short stature in humans. Genetic defects, both established and hypothetical, are reviewed, and a pragmatic clinical approach to the genetic investigation of short-statured patients is presented.