The integrity of the GH-IGF-I axis is essential for normal linear growth in childhood. Defects in either GH secretion or action will result in reducing serum IGF-I, the key growth promoting peptide.

The identification of several new genetic causes of GH deficiency or insensitivity has broadened the range of etiologies responsible for GH disorders. While classical endocrine tests remain the most reliable for assessing the GH-IGF-I axis, analysis of the appropriate candidate genes can contribute to the precise definition of the pathogenesis of the growth disorder.