A commonly occurring polymorphism upstream of the estrogen receptor alpha alters transcription and is associated with increased HDL.

OBJECTIVE

Given the role of estrogen in the regulation of lipid metabolism, we screened for functional polymorphisms in the estrogen receptor alpha (ER*), and examined for their influence on serum cholesterol.

METHODS AND RESULTS

We identified a novel C>T polymorphism (ERNE-145), with a minor allele frequency of 41%. This polymorphism was immediately adjacent to a putative glucocorticoid receptor (GR) binding site, which we showed to be functional by electrophoretic mobility shift analysis. The C allele was associated with glucocorticoid-induced reduction in promoter activity compared to control in luciferase reporter studies (p<0.05; n=7). This effect was abolished by the T allele. To investigate the functional significance of ERNE-145, its association with serum cholesterol levels was examined in 1662 post-menopausal women enrolled in the RUTH trial. ERNE-145 genotype (p=0.001), BMI (p<0.001), diabetes mellitus (p<0.001), and ethnicity (p=0.002) were significantly associated with HDL cholesterol. ERNE-145 genotype explained 8.2% of the variability of HDL: each copy of the variant T allele was associated with a 0.041 mmol/L (CI 0.017-0.066) increase in HDL.

CONCLUSION

A novel polymorphism upstream of ER* abolished negative transcriptional regulation by an adjacent GR binding sequence, and was strongly associated with HDL levels in a large cohort of post-menopausal women.