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

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.