Growth failure associated with primary IGF-1 deficiency (IGFD). Primary IGFD is a term that has been used to describe patients with intrinsic cellular defects in growth hormone (GH) action. In this protocol, primary IGFD is defined as short stature (<-2 standard deviations [SDs] below the mean for age and gender), and abnormal serum IGF-1 (<-2 SDs below the mean for age and gender).