Absence of mutations in exon 3 of the GnRH receptor in human gonadotroph adenomas.

Background And Objective: The mechanisms of tumourogenesis for the majority of pituitary tumours are unknown. Mutations of G-protein coupled receptors (GPCRs) have recently been described as important in diverse human diseases, including thyroid adenomas. To test this hypothesis in pituitary gonadotroph adenomas, we amplified and sequenced the GnRH receptor gene in 12 human tumours. We restricted our analysis to the third exon, since this represents the hotspot for activating mutations in other GPCRs.

Patients: Pituitary adenoma tissue was identified from patients who had tumours resected and where a diagnosis of gonadotroph adenoma had been made on the basis of immunohistochemical demonstration of LH and/or FSH.

Methods: Genomic DNA was extracted from paraffin-embedded tissue of 18 gonadotroph adenomas. The third exon was successfully amplified by PCR in 12 cases and directly sequenced.

Results: We found no missense point mutations or even silent polymorphisms in any tumour studied.

Conclusion: We conclude that activating mutations of the GnRH receptor gene do not represent an important mechanism of pituitary gonadotroph tumourogenesis.