An unusual case of growth hormone receptor deficiency syndrome.

Abstract

Laron-type dwarfism, I a syndrome of growth hormone (GH) receptor deficiency, is an autosomal recessive disorder caused by a variable genetic defect of the GH receptor.s-' The phenotype of the patients with Laron-type dwarfism (LTD) resembles isolated GH deficiency. LTO is characterized by extremely low serum insulin-like growth factor-I (IGF-I) despite normal or high concentrations of biologically active GH and by resistance to exogenous GH. 5 The defect in the GH receptor results in deficiencies of IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3), the major serum carrier protein of IGF peptides.s? Purification and protein sequencing revealed that serum growth hormone binding protein (GHBP) was structurally identical to the extracellular hormone binding domain of the membrane-bound GH receptor. The GHBP was noted to be absent in some LTO patientsv' and normal in others. II We present here an unusual case of GH receptor defect and the members of two unconnected families, one with three siblings with LTO and GHBP-negative phenotype and the other with one child with LTO and GHBPpositive phenotype.