Of the ER22/23EK polymorphism in the Glucocorticoid Receptor Gene with Survival and C-Reactive Protein Levels in Elderly Men

Elisabeth F. C. van Rossum, MD, Richard A. Feelders, MD, PhD, Annewieke W. van den Beld, MD, PhD, Andre G. Uitterlinden, PhD, Joop A. M. J. L. Janssen, MD, PhD, Wietske Ester, MD, Albert O. Brinkmann, Diederick E. Grobbee, PhD, Frank H. de Jong, PhD, Huibert A. P. Pols, MD, Jan W. Koper, PhD, Steven W. J. Lamberts, MD, PhD

Interleukin 6 was determined by a commercially available immulite assay.

PURPOSE: We recently demonstrated that a polymorphism in codons 22 and 23 of the glucocorticoid receptor gene is associated with relative glucocorticoid resistance, greater insulin sensitivity and lower total and low-density lipoprotein cholesterol levels. In the present study, we investigated whether the ER22/23EK polymorphism is associated with survival, cholesterol levels and two predictors of mortality: serum C-reactive protein and interleukin 6 levels.

METHODS: We studied 402 men (mean [SD] age 77.8)

RESULTS: After a follow-up of 4 years, 73 (19%) of 381 non-carriers died while none of the 21 ER22/23EK carriers had died (P = 0.03). C-reactive protein levels were about 50% lower in ER22/23EK carriers (P = 0.01). There were no differences in interleukin 6 levels.

CONCLUSION: Carriers of the ER22/23EK polymorphism have better survival than non-carriers, as well as lower C-reactive protein levels. Am J Med. 2004;117:158-162. 2004 by Elsevier Inc.

METHODS: We studied 402 men (mean [SD] age 77.8) using a latex-enhanced immunoephelometric method, and a commercially available immulite assay to determine the levels of C-reactive protein and interleukin 6. The ER22/23EK variant in codons 22 and 23 of the glucocorticoid receptor gene (GAGAGG [GluArg, or ER] 3 GAAAAG [GluLys, or EK]) is associated with relative glucocorticoid resistance (2). This ER22/23EK variant was also associated with greater insulin sensitivity and lower total and low-density lipoprotein (LDL) cholesterol levels. Furthermore, we found that the number of ER22/23EK carriers was significantly higher in the older half of the sample, suggesting that the polymorphism had a beneficial effect on survival.

SUBJECTS: We recruited 402 men aged 73 years or older by a letter sent to the oldest men in Zoetermeer, The Netherlands. Subjects were eligible to participate if they were physically and mentally able to visit the study center independently. No additional health-related criteria were used. Medications taken for more than 6 months were recorded. Data on vital status of the participants and causes of death during a 4-year follow-up were obtained by contacting the participants' general practitioners. Before the start of the study, which received approval from the Medical Ethics Committee of the Erasmus Medical Center, all subjects had given their written informed consent to participate.

MEASUREMENTS: Weight and height were measured, and body mass index (kg/m2) was calculated. Blood pressure was measured in the sitting position at the right upper arm with a random-zero sphygmomanometer. Total fat mass, trunk fat mass, and lean body mass were measured using dual-energy X-ray absorptiometry (Lunar Corp., Madison, Wisconsin) (12). Quality assurance, including calibration, was performed every morning using the standard provided by the manufacturer.

STATISTICAL ANALYSIS: Data were analyzed using SPSS for Windows, release 10.1 (SPSS, Chicago, Illinois). Differences between the ER22/23EK carriers and the non-carriers were adjusted for age and, if necessary, for body mass index or smoking and tested by analysis of covariance using the general linear model procedure. Bonferroni post hoc tests were used to adjust for multiple comparisons. If dependent variables were not normally distributed, logarithmic transformations were applied to normalize them or nonparametric tests (Mann-Whitney U test) were used. Continuous variables are reported as mean [SD] or median (interquartile range). Survival was analyzed using the Kaplan-Meier procedure and log-rank test. To studyActivities of daily life: 9 points (812), 9 points (811)
Physical performance: 9 points (710), 9 points (711)
Number of chronic diseases: 3 (15), 3 (15)

All parameters were adjusted for age. C-reactive protein and interleukin 6 values were logarithmically transformed for statistical analysis. Lean mass and fat mass were adjusted for height. Blood pressure and lipids were adjusted for body mass index. To convert total, HDL, and LDL cholesterol levels from mmol/L to mg/dL, multiply by 38.67. To convert triglyceride levels, multiply by 89.15. To convert C-reactive protein levels from mg/L to mg/dL, divide by 10. HDL: high-density lipoprotein; LDL: low-density lipoprotein.

The ER22/23EK carriers have lower fasting insulin and cholesterol levels due to the effects of glucocorticoids. Perhaps the lower C-reactive protein levels observed in ER22/23EK carriers are related to, and possibly even due to, having less atherosclerosis. No differences in body mass index, blood pressure, or levels of HDL cholesterol, triglycerides, or interleukin 6 were found between ER22/23EK carriers and noncarriers.

Greater body mass index, particularly fat mass, is related to higher levels of interleukin 6 and C-reactive protein. In these elderly men, we found that C-reactive protein level correlated positively with body mass index and fat mass, but there was no association between interleukin 6 and these parameters. No differences in body mass index or fat mass were observed by genotype.