Effects of the Infusion of Insulin-like Growth Factor I in a Child with Growth Hormone Insensitivity Syndrome (Laron Dwarfism)

Abstract

THE clinical manifestations of the growth hormone insensitivity syndrome (Laron dwarfism) result from the inability of growth hormone to exert its biologic actions.^{1 , 2} Affected children have the severe growth retardation and other physical characteristics of growth hormone deficiency and low serum insulin-like growth factor I (IGF-I) concentrations.^{1 , 2} Unlike children with growth hormone deficiency, however, children with growth hormone insensitivity syndrome have high serum growth hormone concentrations, and treatment with growth hormone does not raise their IGF-I concentrations or stimulate growth.^{1 , 2} The conclusion that the syndrome is due to abnormal or deficient cellular growth hormone receptors is supported by the finding of abnormal binding of growth hormone to liver membranes in two patients³ and by the absence of the structurally related serum growth hormone—binding protein in affected persons.^{4 , 5} Molecular studies of the growth hormone receptor in growth hormone insensitivity syndrome suggest that a variety of receptor,^{6 , 7} and perhaps postreceptor, defects are likely to be responsible for the syndrome. We propose the term "growth hormone insensitivity syndrome" as an alternative to "Laron dwarfism," in recognition of the etiologic heterogeneity of the condition and to avoid the stigma associated with the term "dwarf."