IGF-I deficiency due to GH receptor deficiency.

IGF-I deficiency may be primary due to defective synthesis, or secondary to GH receptor deficiency (GHRD) or defects in transduction of the GH-GHR signal. Cloning and sequencing of the GHR led to recognition that circulating GH binding protein (GHBP) was structurally identical to the extra-cellular domain of the GHR, and the identification of 33 mutations of the GHR in approximately half of the 250 patients that have been reported. This review explores the information provided about GHR function by various mutations, the population distribution of GHRD, the effects of this condition on mortality, growth, development, and metabolism, the effects of replacement therapy with recombinant human IGF-I, diagnostic issues, and the question of partial GH resistance.