Analysis of the influence of the T393C polymorphism of the GNAS gene on the clinical expression of primary hyperparathyroidism.

BACKGROUND

The receptor of parathyroid hormone and parathyroid hormone-related-protein (PTH/PTHrp) is located in the cell membrane of target tissues - kidney and osteoblasts. It is a G protein-coupled-receptor whose Gsα subunit is encoded by the GNAS gene. Our aim was to study whether the single nucleotide polymorphism (SNP) T393C of the GNAS gene is associated with renal stones, bone mineral density (BMD), or bone remodelling markers in primary hyperparathyroidism (PHPT).

METHODS

An analysis was made of clinical and biochemical parameters and densitometric values in three areas and their relationship with the T393C SNP of the GNAS gene in 261 patients with primary hyperparathyroidism and in 328 healthy controls. Genotyping was performed using the Custom Taqman® SNP Genotyping assay.

RESULTS

The genotype frequencies of GNAS T/C 393 were similar in the control and PHPT groups. No association was found between genotypes and clinical expression of PHPT (renal stones and bone fractures). A nonstatistically significant trend was seen to lower BMD in the lumbar spine, femoral neck, and total hip in both PHPT and control C homozygote subjects.

CONCLUSION

Genetic susceptibility to PHPT related to the GNAS T393C polymorphism or a major influence in its development and clinical expression were found. A C allele-related susceptibility to lower BMD in trabecular bone in both PHPT and control subjects is not sufficient to suggest a more severe clinical expression of PHPT. This trend may be considered as a basis for further studies with larger sample sizes and complementary functional evaluation.