Project description:ContextSerum estradiol (E2) and estrone (E1) levels exhibit substantial heritability.ObjectiveTo investigate the genetic regulation of serum E2 and E1 in men.Design, setting, and participantsGenome-wide association study in 11,097 men of European origin from nine epidemiological cohorts.Main outcome measuresGenetic determinants of serum E2 and E1 levels.ResultsVariants in/near CYP19A1 demonstrated the strongest evidence for association with E2, resolving to three independent signals. Two additional independent signals were found on the X chromosome; FAMily with sequence similarity 9, member B (FAM9B), rs5934505 (P = 3.4 × 10-8) and Xq27.3, rs5951794 (P = 3.1 × 10-10). E1 signals were found in CYP19A1 (rs2899472, P = 5.5 × 10-23), in Tripartite motif containing 4 (TRIM4; rs17277546, P = 5.8 × 10-14), and CYP11B1/B2 (rs10093796, P = 1.2 × 10-8). E2 signals in CYP19A1 and FAM9B were associated with bone mineral density (BMD). Mendelian randomization analysis suggested a causal effect of serum E2 on BMD in men. A 1 pg/mL genetically increased E2 was associated with a 0.048 standard deviation increase in lumbar spine BMD (P = 2.8 × 10-12). In men and women combined, CYP19A1 alleles associated with higher E2 levels were associated with lower degrees of insulin resistance.ConclusionsOur findings confirm that CYP19A1 is an important genetic regulator of E2 and E1 levels and strengthen the causal importance of E2 for bone health in men. We also report two independent loci on the X-chromosome for E2, and one locus each in TRIM4 and CYP11B1/B2, for E1.
Project description:ContextEstradiol is the primary female sex hormone and plays an important role for skeletal health in both sexes. Several enzymes are involved in estradiol metabolism, but few genome-wide association studies (GWAS) have been performed to characterize the genetic contribution to variation in estrogen levels.ObjectiveIdentify genetic loci affecting estradiol levels and estimate causal effect of estradiol on bone mineral density (BMD).DesignWe performed GWAS for estradiol in males (n = 147 690) and females (n = 163 985) from UK Biobank. Estradiol was analyzed as a binary phenotype above/below detection limit (175 pmol/L). We further estimated the causal effect of estradiol on BMD using Mendelian randomization.ResultsWe identified 14 independent loci associated (P < 5 × 10-8) with estradiol levels in males, of which 1 (CYP3A7) was genome-wide and 7 nominally (P < 0.05) significant in females. In addition, 1 female-specific locus was identified. Most loci contain functionally relevant genes that have not been discussed in relation to estradiol levels in previous GWAS (eg, SRD5A2, which encodes a steroid 5-alpha reductase that is involved in processing androgens, and UGT3A1 and UGT2B7, which encode enzymes likely to be involved in estradiol elimination). The allele that tags the O blood group at the ABO locus was associated with higher estradiol levels. We identified a causal effect of high estradiol levels on increased BMD in both males (P = 1.58 × 10-11) and females (P = 7.48 × 10-6).ConclusionOur findings further support the importance of the body's own estrogen to maintain skeletal health in males and in females.
Project description:Strenuous training commonly results in amenorrhoea, which contributes to bone loss in some female collegiate athletes. However, the impact of athletic training on endocrine function and bone mineral density (BMD) in male collegiate athletes is less well understood. The objective of the study was to investigate the specific endocrine determinants of BMD in male collegiate runners and wrestlers, including the potential impact of gonadal steroid levels.? Cross-sectional study.? Twenty-six division I collegiate male athletes (wrestlers, runners and golfers).? Main outcome measures included (i) BMD endpoints measured by dual energy x-ray absorptiometry (DXA); (ii) endocrine end-points: total and free oestradiol, total and free testosterone; (iii) body composition end-points: lean and fat mass, measured by DXA; and (iv) exercise end-points: maximal oxygen uptake (VO(2) max), number of miles run weekly and grip strength.? Free and total oestradiol levels were important positive determinants of BMD. In contrast, total and free testosterone levels were not significant predictors of BMD at any skeletal site (except for free testosterone at the radius). In addition, lean body mass, % ideal body weight, total body weight, body mass index (BMI) and hours per week of resistance training were positive predictors of BMD. VO(2) max was a negative predictor of BMD. Mean BMD was higher at all skeletal sites in the wrestlers compared with the runners and a comparison group (golfers).? Our data suggest that oestradiol levels, BMI, and resistance training are more important determinants of BMD in male collegiate athletes than testosterone.
Project description:BackgroundYounger age at the onset of menopause and lower circulating levels of estrogen are risk factors for cardiovascular disease. Several studies have detected associations between variations in genes encoding estrogen receptors alpha (ESR1) and beta (ESR2), and enzyme aromatase (CYP19A1), which regulates the estrogen to testosterone ratio, and cardiovascular phenotypes in the Framingham Heart Study. To explore potential mechanisms by which these gene variants may contribute to cardiovascular disease, we tested the hypothesis that the polymorphisms were associated with endogenous steroid hormone levels.MethodsMultiple regression analysis was used to assess the relation between reported polymorphisms and total serum estradiol, testosterone, and dehydroepiandrosterone sulfate levels in 834 men and 687 women who attended the third and fourth Framingham Heart Study examination cycles.ResultsIn men, significant associations were detected between CYP19A1 polymorphisms and estradiol and testosterone levels, and the estradiol to testosterone ratio (P ranges 0.0005-0.01). Specifically, carriers of common haplotype rs700518[G]-(TTTA)(n) [L]-rs726547[C] had higher estradiol levels (5% per copy; P = 0.0004), lower testosterone levels (17% per copy; P = 0.036), and a higher estradiol to testosterone ratio (24% per copy; P < 0.0001) compared with the rs700518[A]-(TTTA)(n) [S]-rs726547[C] carriers. In addition, postmenopausal carriers of the ESR2 (CA)(n) long allele and rs1256031 [C] allele had moderately higher estradiol levels (P < or = 0.03). No significant associations with the ESR1 variants were detected.ConclusionsOur findings suggest that variations in CYP19A1 correlate with steroid hormone levels in men. Knowledge that a specific carrier status may predispose to altered steroid hormone levels may lead to targeted intervention strategies to reduce health risks in genetically susceptible individuals.
Project description:BackgroundVitamin K modulates cytokines involved in bone turnover, including interleukin-6 (IL-6) and osteoprotegerin in vitro.ObjectiveThe objective of this study was to assess 1) associations between measures of vitamin K status [plasma phylloquinone and serum percentage of undercarboxylated osteocalcin (%ucOC)] and IL-6, osteoprotegerin, and C-reactive protein (CRP) concentrations and 2) the effect of daily 500 mug phylloquinone supplementation for 3 y on cytokine concentrations.DesignConcentrations of IL-6, osteoprotegerin, and CRP and bone mineral density (BMD) were measured at baseline and after 3 y of follow-up in 379 healthy men and women (60-81 y; 58.5% women) participating in a randomized trial that studied the effect of vitamin K supplementation on bone loss.ResultsCross-sectionally, plasma phylloquinone was inversely associated with IL-6 and CRP, whereas serum %ucOC was inversely associated with IL-6. Osteoprotegerin was associated positively with plasma phylloquinone and inversely with %ucOC. No differences were observed in the 3-y change in IL-6, osteoprotegerin, and CRP concentrations between participants who received phylloquinone supplementation and those who did not. Overall, no association was observed between the 3-y changes in circulating cytokines and BMD.ConclusionsPoor vitamin K status was associated with high concentrations of cytokines involved in bone turnover, but vitamin K supplementation did not confer a decrease in cytokine concentrations. The healthy status of this cohort may explain a lack of effect of vitamin K supplementation on cytokine concentrations. This trial was registered with www.clinicaltrials.gov as NCT00183001.
Project description:Recent cohort studies indicate a potential role of the antioxidant α-tocopherol in reducing bone loss and risk of fractures, especially hip fractures. We performed a Mendelian randomization investigation of the associations of circulating α-tocopherol with estimated bone mineral density (eBMD) using heel ultrasound and fractures, identified from hospital records or by self-reports and excluding minor fractures. Circulating α-tocopherol was instrumented by three genetic variants associated with α-tocopherol levels at p < 5 × 10-8 in a genome-wide association meta-analysis of 7781 participants of European ancestry. Summary-level data for the genetic associations with eBMD in 426,824 individuals and with fracture (53,184 cases and 373,611 non-cases) were acquired from the UK Biobank. Two of the three genetic variants were strongly associated with eBMD. In inverse-variance weighted analysis, a genetically predicted one-standard-deviation increase of circulating α-tocopherol was associated with 0.07 (95% confidence interval, 0.05 to 0.09) g/cm2 increase in BMD, which corresponds to a >10% higher BMD. Genetically predicted circulating α-tocopherol was not associated with odds of any fracture (odds ratio 0.97, 95% confidence interval, 0.91 to 1.05). In conclusion, our results strongly strengthen a causal link between increased circulating α-tocopherol and greater BMD. Both an intervention study in those with a low dietary intake of α-tocopherol is warranted and a Mendelian randomization study with fragility fractures as an outcome.
Project description:ObjectivesAmong postmenopausal women taking hormone therapy (HT), the estradiol (E2) dose and E2 levels were differentially associated with change in metabolic measures. We evaluated determinants of attained E2 levels in response to HT.MethodsPostmenopausal women from the REPLENISH trial tested four formulations of oral combined E2 and progesterone compared with placebo. Mixed-effects linear models assessed characteristics associated with E2 levels among women with ≥80% HT compliance, adjusted for E2 dose and baseline E2 level.ResultsAmong 1173 postmenopausal women with mean (standard deviation) age 55 (4.3) years and 5.2 (4.8) years since menopause, higher treated E2 levels were significantly related to younger age, more recent menopause, and current alcohol use, while lower E2 levels were related to current smoking. Both age and time since menopause were significantly inversely associated with E2 levels; time since menopause had a stronger association with E2 levels. In the final multivariable model, E2 levels were positively associated with current alcohol use, and inversely associated with time since menopause and current smoking.ConclusionAdjusting for E2 dose and baseline E2 level, on-trial E2 levels were significantly associated with time since menopause, current smoking, and current alcohol use. Practitioners should consider these factors in individual women to achieve a desirable E2 level during HT.
Project description:Until recently, randomized controlled trials have not demonstrated convincing evidence that vitamin D, or vitamin D in combination with calcium supplementation could improve bone mineral density (BMD), osteoporosis and fracture. It remains unclear whether vitamin D levels are causally associated with total body BMD. Here, we performed a Mendelian randomization study to investigate the association of vitamin D levels with total body BMD using a large-scale vitamin D genome-wide association study (GWAS) dataset (including 79 366 individuals) and a large-scale total body BMD GWAS dataset (including 66,628 individuals). We selected three Mendelian randomization methods including inverse-variance weighted meta-analysis (IVW), weighted median regression and MR-Egger regression. All these three methods did not show statistically significant association of genetically increased vitamin D levels with total body BMD. Importantly, our findings are consistent with recent randomized clinical trials and Mendelian randomization study. In summary, we provide genetic evidence that increased vitamin D levels could not improve BMD in the general population. Hence, vitamin D supplementation alone may not be associated with reduced fracture incidence among community-dwelling adults without known vitamin D deficiency, osteoporosis, or prior fracture.
Project description:ContextA major determinant of osteoporotic fractures is peak bone mineral density (BMD), which is a highly heritable trait. Recently, we identified significant linkage for hip BMD in premenopausal sister pairs at chromosome 14q (LOD score = 3.5), where the estrogen receptor beta gene (ESR2) is located.ObjectiveThe objective of the study was to determine whether ESR2 polymorphisms are associated with normal BMD variation.DesignThis was a population-based genetic association study, using 11 single nucleotide polymorphisms (SNPs) distributed across the ESR2 gene.SettingThe study was conducted at an academic research laboratory and medical center.Patients and other participantsA total of 411 healthy men (aged 18-61 yr) and 1291 healthy premenopausal women (aged 20-50 yr) living in Indiana participated in the study.Intervention(s)There were no interventions.Main outcome measure(s)The main outcome measures were SNP genotype distributions and their association with BMD at the femoral neck and lumbar spine.ResultsSignificant association of spine BMD was found with three SNPs in men and one SNP in women (P < or = 0.05). The conditional linkage analysis using the ESR2 haplotypes showed that the ESR2 gene accounts for, at most, 18% of the original linkage.ConclusionsESR2 polymorphisms are significantly associated with bone mass in both men and women. However, the ESR2 gene is not entirely responsible for our original linkage, and an additional gene(s) in chromosome 14q contributes to the determination of BMD.