OBJECTIVE: The association of four single nucleotide polymorphisms in estrogen receptor alpha (ESR1) and beta (ESR2) genes with lipid levels and insulin resistance in men.
DESIGN AND METHODS: Lipids, glucose, insulin and HOMA-IR were determined, in a population-based, cross-sectional, cohort of 170 apparently healthy middle-aged Greek men, along with body mass index (BMI), waist circumference (WC) and percentage of body fat content (%fat). Genotyping of ESR1 for PvuII and XbaI and ESR2 for RsaI and AluI polymorphisms was performed.
RESULTS: Associations of AluI with LDL-Chol (mean ± SD, aa 4.3 ± 1.1 vs. Aa 3.7 ± 1.0 and ΑΑ 4.2 ± 1.1, p = 0.023) and RsaI with HOMA-IR [median (IQR), RR 1.55 (0.88-2.49) vs. Rr/rr 1.69 (0.72-2.29), p = 0.032] were found. Synergistic effects of RsaI and AluI of ESR2 gene on LDL-Chol levels, %fat and WC, as well as a synergistic effect of both ESR1 and ESR2 genes on levels of TChol (p = 0.01) and LDL-Chol (p = 0.027) were also shown. These findings remained significant after adjustment for potential confounders. Significant independent associations of PvuII with %fat (mean ± SD, pp 24.6 ± 5.3 vs Pp 22.4 ± 5.2 and PP 21.2 ± 6.7, p = 0.044), and RsaI with %fat (RR 22.6 ± 5.5 vs. Rr/rr 25.2 ± 6.3, p = 0.015) and WC (mean ± SD, RR 97.4 ± 10.4 vs. Rr/rr 102.6 ± 12.6, p = 0.013) were found. Synergistic effects on %fat, between the ESR1 polymorphisms (p = 0.004), between the ESR2 polymorphisms and among all four ESR polymorphisms studied were also present.
CONCLUSIONS: ESR2 is associated with LDL-Chol levels and HOMA-IR in men independently of confounders. Body fat is affected by both genes. Furthermore, a synergistic effect of ESR1 and ESR2 on TChol, LDL-Chol and %fat, was shown.