Genetic Variations in Sex Steroid-Related Genes as Predictors of Serum Estrogen Levels in Men

Abstract

Context: The risk of many conditions, including prostate cancer, breast cancer, and osteoporosis, is associated with serum levels of sex steroids. Objective: The aim of the study was to identify genetic variations in sex steroid-related genes that are associated with serum levels of estradiol (E2) and/or testosterone in men. Design: Genotyping of 604 single nucleotide polymorphisms in 50 sex steroid-related candidate genes was performed in the Gothenburg Osteoporosis and Obesity Determinants (GOOD) study (n = 1041 men; age, 18.9 ± 0.6 yr). Replications of significant associations were performed in the Osteoporotic Fractures in Men (MrOS) Sweden study (n = 2568 men; age, 75.5 ± 3.2 yr) and in the MrOS US study (n = 1922 men; age, 73.5 ± 5.8 yr). Serum E2, testosterone, and estrone (E1) levels were analyzed using gas chromatography/mass spectrometry. Results: The screening in the GOOD cohort identified the single nucleotide polymorphism rs2470152 in intron 1 of the CYP19 gene, which codes for aromatase, responsible for the final step of the biosynthesis of E2 and E1, to be most significantly associated with serum E2 levels (P = 2 × 10⁻⁶). This association was confirmed both in the MrOS Sweden study (P = 9 × 10⁻⁷) and in the MrOS US study (P = 1 × 10⁻⁴). When analyzed in all subjects (n = 5531), rs2470152 was clearly associated with both E2 (P = 2 × 10⁻¹⁴) and E1 (P = 8 × 10⁻¹⁹) levels. In addition, this polymorphism was modestly associated with lumbar spine BMD (P < 0.01) and prevalent self-reported fractures (P < 0.05). Conclusions: rs2470152 of the CYP19 gene is clearly associated with serum E2 and E1 levels in men.