D3 GH receptor polymorphism is not associated with IGF1 levels in untreated acromegaly

Abstract

CONTEXT: A discrepancy between serum GH and IGF1 concentrations is frequent in patients with acromegaly. Here, we examined whether the exon 3-deleted (d3) GH receptor (GHR) variant, which has been linked to increased responsiveness to GH treatment in short children, influences the GH/IGF1 relationship in patients with acromegaly. OBJECTIVE: To study the possible influence of the GHR genotype on the GH/IGF1 relationship in untreated acromegalic patients. DESIGN: GHR genotype analysis with retrospective clinical and biochemical data collection performed in a single third-reference medical center. PATIENTS AND METHODS: Clinical data were obtained from the medical records of 105 acromegalic patients who had GH and IGF1 assays in the same laboratory and who were genotyped for the full-length (fl) or d3-GHR alleles. RESULTS: The distribution of GHR genotypes was 51% fl/fl, 30% fl/d3, and 19% d3/d3. Patients with d3/d3 genotype were younger than the patients in the other two groups (P<0.05). Baseline GH and IGF1 concentrations did not differ among the three groups. The linear correlation between GH and IGF1 concentrations was similar in the three genotypic groups. CONCLUSIONS: The exon 3 GHR genotype does not affect the GH/IGF1 relationship in untreated acromegalic patients with high circulating GH and IGF1 levels.