BclI polymorphism of the glucocorticoid receptor gene is associated with decreased bone mineral density in patients with endogenous hypercortisolism

P>Objective The hypothalamic-pituitary-adrenal axis setpoint and the glucocorticoid sensitivity of various tissues are at least partially genetically determined. We investigated the impact of glucocorticoid receptor (GR) gene polymorphisms, including the BclI, N363S, ER22/23EK and A3669G variants on bone turnover and/or mineral density (BMD) in patients with endogenous glucocorticoid excess. Design Sixty patients including 35 patients with ACTH producing pituitary adenoma (CD) and 25 patients with adrenal Cushing's syndrome (ACS) as well as 129 healthy subjects were genotyped. Analysis of the GR gene polymorphisms were determined using allele specific PCR, PCR-RFLP and Taqman allelic discrimination assays. Hormonal evaluation, BMD and bone marker measurements were carried out. Results No significant differences were found in allelic frequencies of the four polymorphisms between patients with ACS, CD and healthy controls. Patients with endogenous hypercortisolism carrying the BclI polymorphism in a homozygous form had reduced BMD at femoral subregions compared to patients with the wild-type variant; femoral neck Z-score (-1 center dot 44 +/- 0 center dot 73 vs. -0 center dot 39 +/- 0 center dot 91; P < 0 center dot 05), trochanteric Z-score (-1 center dot 89 +/- 0 center dot 47 vs.-0 center dot 54 +/- 0 center dot 98; P < 0 center dot 05). Patients with homozygous BclI polymorphism had significantly higher beta-CrossLaps Z-scores compared to those with the heterozygous and wild-type variants (+4 center dot 42 +/- 2 center dot 37 vs. +0 center dot 79 +/- 1 center dot 67 and +0 center dot 11 +/- 1 center dot 47; P < 0 center dot 01). Conclusions The BclI, N363S, ER22/23EK and A3669G polymorphisms of the GR gene probably do not modify the risk for the development of CD or ACS. Contrary to healthy subjects, however, the BclI polymorphism may modify the skeletal sensitivity to glucocorticoids in patients with endogenous glucocorticoid excess.