Laron-type dwarfism with apparently normal high affinity serum growth hormone-binding protein.

Abstract

OBJECTIVE:

Normal serum contains a high affinity GH-binding protein, which appears to be identical with the extracellular domain of the GH receptor. It is normally absent from the serum of patients with Laron-type dwarfism. We wished in this study to define the serum GH-binding protein status of a family with Laron-type dwarfism.

DESIGN AND PATIENTS:

We performed an open case study of an Asian family in which three sisters (aged 3 to 15 years) had the phenotype of Laron-type dwarfism. Sera from a fourth, unrelated girl with Laron-type dwarfism and subjects without endocrine disorders were used as control samples.

MEASUREMENTS:

Laron-type dwarfism was confirmed by demonstration of elevated serum GH levels and low serum IGF-I levels on immunoassay, with serum IGF-I levels failing to rise during treatment with GH. Serum GH-binding proteins were characterized using gel chromatography on Sephacryl S-100HR following incubation of serum with 125I-GH, Scatchard analysis of ligand binding, and by polyacrylamide gel electrophoresis after covalent cross-linking to 125I-GH.

RESULTS:

All members of the family had high affinity serum GH-binding protein activity similar in size, circulating levels and apparent affinity for GH to that of normal subjects. This contrasted with the very low serum GH-binding protein activity in the unrelated child with Laron-type dwarfism and previous reports of serum GH-binding protein levels in this disorder.

CONCLUSIONS:

The affected patients may possess a novel biochemical defect which results in GH-resistance and reduced production of IGF-I in the presence of normal serum GH-binding protein levels.

• Authors: C R Buchanan, H G Maheshwari, M R Norman, D J Morrell, M A Preece
• Journal: Clinical endocrinology (Clin Endocrinol (Oxf)) Vol. 35 Issue 2 Pg. 179-85 (Aug 1991) ISSN: 0300-0664 [Print] England
• PMID: 1934534 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Receptors, Somatotropin
• Insulin-Like Growth Factor I
• Growth Hormone

Topics

• Adolescent
• Child
• Chromatography, Gel
• Dwarfism (blood, genetics, metabolism)
• Electrophoresis, Polyacrylamide Gel
• Female
• Growth Hormone (blood)
• Humans
• Insulin-Like Growth Factor I (metabolism)
• Receptors, Somatotropin (analysis, metabolism)