IMMUNOREACTIVE GROWTH-HORMONE RECEPTOR BINDING PROTEIN IS PRESENT ON FIBROBLASTS AND IN SERUM OF LARON-TYPE DWARFS/

Laron-type dwarfism is an autosomal recessive disorder characterised b y extreme growth retardation and growth hormone (GH) resistance and ha s been shown in some cases to be associated with mutations in the GH r eceptor gene. Limited data suggest that in this condition specific liv er GH binding is absent. In the majority of reported cases specific GH binding is also absent in serum. However it is not known whether the GH receptor and/or the serum GH binding protein are expressed in this condition. Using the techniques of immunohistochemistry and Northern b lotting we have demonstrated that in cultured skin fibroblasts derived from four patients with Laron-type dwarfism the GH receptor gene is t ranscribed and the GH receptor protein is expressed on the cell surfac e. Further study of one of these patients, who has not previously been reported, has also revealed low but detectable levels of GH binding p rotein in serum using a two-site immunradiometric assay which does not depend on GH binding. These results indicate that the growth hormone receptor/binding protein is expressed in Laron-type dwarfism.