The association of bone mineral density with estrogen receptor gene polymorphisms

Association between the ESR1 and ESR2 polymorphisms and osteoporosis risk: An updated meta-analysis

BACKGROUND

Gene polymorphisms of estrogen receptor (ESR) 1 PvuII (rs2234693), XbaI (rs9340799), G2014A (rs2228480), ESR2 AluI (rs4986938), and RsaI (rs1256049) had been reported to be associated with the risk of osteoporosis. However, these conclusions were inconsistent, therefore, an updated meta-analysis was conducted to further explore these issues.

OBJECTIVE

To evaluate the association between gene polymorphisms of ESR1 PvuII (rs2234693), XbaI (rs9340799), G2014A (rs2228480), ESR2 AluI (rs4986938), RsaI (rs1256049), and osteoporosis risk.

MATERIALS AND METHODS

PubMed, Medline, Ovid, Embase, CNKI, and China Wanfang databases were searched. Association was assessed using odds ratio with 95% confidence interval. Moreover, the false-positive reporting probability, Bayesian false-finding probability, and Venetian criteria were used to assess the credibility of statistically significant associations.

RESULTS

Overall, ESR1 PvuII (rs2234693) and XbaI (rs9340799) were associated with the risk of osteoporosis in Indians. Moreover, ESR1 G2014A (rs2228480) was associated with the decreased risk of osteoporosis in East Asians. Moreover, ESR2 Alul (rs4986938) was associated with the increased risk of osteoporosis in East Asians and Caucasians. There was a significant association between ESR2 Rsal (rs1256049) and osteoporosis risk in overall population. When only high-quality and Hardy-Weinberg equilibrium studies were included in the sensitivity analysis, all results did not change in the present study. When the credibility was evaluated applying false-positive reporting probability, Bayesian false-finding probability, and Venetian criteria, all significant associations were considered as false positive results.

CONCLUSIONS

In summary, this study shows that all substantial associations between gene polymorphisms of ESR1 (PvuII, XbaI, and G2014A) and ESR 2 (AluI and RsaI) and osteoporosis risk are possibly false positive results instead of real associations or biological variables.

ESR2 gene variants (rs1256049, rs4986938, and rs1256030) and their association with breast cancer risk

Background

Variants of the estrogen receptor b (ESR2) gene have been associated with different types of cancer. However, these associations have been inconsistent. We genotyped the ESR2 variants (rs1256049, rs4986938, and rs1256030) in breast cancer (BC) patients and in healthy women.

Results

The variants rs1256049 and rs4986938 in the ESR2 gene were not associated with risk susceptibility in BC patients. However, the rs1256030 variant had an association as a risk factor for BC patients when compared with controls and BC patients for the TT genotype (odds ratio (OR) 1.86, 95% confidence intervals (CI) [1.05-3.28], p = 0.042). In addition, differences were observed in patients and controls carrying the TT genotype under 50 years of age (OR 1.85, 95% CI [1.05-3.27], p = 0.043). Thus, evident differences showed the rs1256030 variant in patients with TT, TC, and TC+TT genotypes with: (1) Stage IV (OR 1.60, 95% CI [1.06-2.54], p = 0.033), and (2) Luminal A (OR 1.60, 95% CI [0.47-0.21], p = 0.041), as well as in BC carriers of the TT genotype with indices of cellular proliferative (Ki-67) elevated (>20%) and overweight (OR 1.67, 95% CI [0.85-3.28], p = 0.041), respectively. In BC HER2 with lymph node metastasis, the TT genotype was a protective factor (OR 0.38, 95% CI [0.18-0.78], p = 0.005). The identification of haplotypes included two common GAT as risk factors (OR 3.1, 95% CI [1.31-7.72], p = 0.011) and GGC as a protective factor (OR 0.7, 95% CI [0.60-0.97], p = 0.034). The haplogenotype GGGATC was a risk factor (OR 2.5, 95% CI [1.28-5.0], p = 0.008).

Conclusion

The variant rs1256030 (TT) of the ESR2 gene and haplotype GAT were associated with susceptibility to BC as risk factors in this sample from the Mexican population.

Menopausal hormone therapy for the management of osteoporosis

Postmenopausal osteoporosis is a frequent clinical condition which affects nearly 1 in 3 women. Estrogen deficiency leads to rapid bone loss which is maximal within the first 2-3 years after the menopause transition and can be prevented by menopause hormone therapy (MHT). Not only, MHT prevents bone loss and the degradation of the bone microarchitecture but it significantly reduces the risk of fracture at all bone sites by 20-40%. It is the only anti-osteoporotic therapy that has a proven efficacy regardless of basal level of risk, even in low-risk women for fracture. Following the publication of the WHI results, use of MHT has considerably declined due to safety concerns which raise the question as to whether it might still be used in the prevention of osteoporosis. Over the last years, subsequent re-analyses of the WHI and further trials have challenged the initial conclusions of the WHI. It is now clearer that the individual benefit-risk balance of MHT is dependent on the individual risk profile in each woman as well as whether estrogen is opposed or unopposed, the type of estrogens and progestogens or doses and routes of administration. It must be also reminded that to date osteoporosis is a chronic disease that cannot be cured. The choice of the 1st treatment option should thus always be made in the context of a more comprehensive long-term strategy. This is particular true in early postmenopausal women found to be at low/moderate risk of fragility fracture over the first 10 years after menopause but who may have a much greater lifetime risk. In the absence of contraindication, use of MHT should be considered as a 1st option for the maintenance of bone health in those women where specific bone active medications are not warranted. Subsequent reassessment of the individual benefit-risk balance of MHT is thereafter recommended, with the possibility of switching to another osteoporosis treatment if the balance is not considered as favourable as at the beginning of the menopause for women still at high risk of fracture.

[Menopause, menopause hormone therapy and osteoporosis. Postmenopausal women management: CNGOF and GEMVi clinical practice guidelines]

Postmenopausal osteoporosis is a frequent clinical condition, which affects nearly 1 in 3 women. Estrogen deficiency leads to rapid bone loss, which is maximal within the first years after the menopause transition and can be prevented by menopause hormone therapy (MHT). Assessment of the individual risk of osteoporosis is primarily based on the measurement of bone mineral density (BMD) at the spine and femur by DXA. Clinical risk factors (CRFs) for fractures taken either alone or in combination in the FRAX score were shown not to reliably predict fractures and/or osteoporosis (as defined by a T-score<-2.5) in early postmenopausal women. If DXA measurement is indicated in all women with CRFs for fractures, it can be proposed on a case-by-case basis, when knowledge of BMD is likely to condition the management of women at the beginning of menopause, particularly the benefit-risk balance of MHT. MHT prevents both bone loss and degradation of the bone microarchitecture in early menopause. It significantly reduces the risk of fracture at all bone sites by 20 to 40% regardless of basal level of risk with an estrogen-dependent dose-effect. Given the inter-individual variability in bone response, individual monitoring of the bone effect of MHT is warranted when prescribed for the prevention of osteoporosis. This monitoring is based on repeated measurement of lumbar and femoral BMD (on the same DXA measurement system) after 2years of MHT, the response criterion being no significant bone loss. Discontinuation of treatment is associated with a resumption of transient bone loss although there is a large variability in the rate of bone loss among women. Basically, there is a return to the level of fracture risk comparable to that of in untreated woman of the same age within 2 to 5years. Therefore, when MHT is prescribed for the prevention of osteoporosis in women with an increased risk at the beginning of menopause, measurement of BMD is recommended when MHT is stopped in order to consider further management of the risk of fracture whenever necessary (with possibly another anti-osteoporotic treatment).

Is the beta estradiol receptor receiving enough attention for its metabolic importance in postmenopause?

The relationship between menopause and the development of metabolic diseases is well established. In postmenopause women, there is an expansion of visceral white adipose tissue (WATv), which highly contributes to the rise of circulating lipids. Meanwhile, muscle glucose uptake decreases and hepatic glucose production increases. Consequently, in the pancreas, lipotoxicity and glycotoxicity lead to deficient insulin production. These factors initiate an energy imbalance and enhance the probability of developing cardiovascular and metabolic diseases. Although the activation of estradiol receptors (ER) has been shown to be beneficial for the WAT stock pattern, leading to the insulin-sensitive phenotype, authors have described the risk of these receptors' activation, contributing to neoplasia development. The selective activation of beta-type ER (ERβ) seems to be a promising strategy in the treatment of energy imbalance, acting on several tissues of metabolic importance and allowing an intervention with less risk for the development of estrogen-dependent neoplasia. However, the literature on the risks and benefits of selective ERβ activation still needs to increase. In this review, several aspects related to ERβ were considered, such as its physiological role in tissues of energy importance, beneficial effects, and risks of its stimulation during menopause. PubMed, SciELO, Cochrane, and Medline/Bireme databases were used in this study.

Association of ESR1 polymorphism rs2234693 and rs9340799 with postmenopausal osteoporosis in a Chinese population

Background

Postmenopausal osteoporosis (PMO) is the most common type of primary osteoporosis. ESR1 polymorphism rs2234693 and rs9340799 has been widely studied as a candidate gene associated with PMO, however, the findings were inconclusive. The present study aims to explore the relationship of ESR1 polymorphism rs2234693 and rs9340799 with PMO risk in a Chinese Han population.

Methods

PMO patients and healthy controls were recruited from gynecology department. DNA of all participants were extracted from the peripheral blood samples and genotyped by Mass Array method. A meta-analysis of case control studies was also conducted to further elucidate the relationship of polymorphism with PMO.

Results

Our results revealed that there were no associations of rs2234693 with PMO. However, GG genotype of rs9340799 was associated with a higher risk of PMO (OR = 1.51, 95%CI:1.08–4.34, p = 0.03), even adjusting for risk factors (OR = 1.83, 95%CI: 1.12–5.04, p = 0.04). Logistic regression analysis showed that dominant model was associated with a higher risk of PMO (OR = 2.07, 95%CI: 1.02–5.16, p = 0.02) after correcting the risk factors (OR = 2.14, 95%CI:1.12–5.64, p = 0.04); In addition, the Meta-analysis results revealed that both two polymorphisms were not associated with PMO.

Conclusions

In conclusion, ESR1 polymorphism rs9340799 was associated with PMO. However, well designed studies with larger sample sizes are required to further elucidate the associations.

The rs1256044 polymorphism in the ESR2 gene and the risk for osteoporosis in Polish postmenopausal women

Population association studies have demonstrated a strong association between ESR2 SNPs and BMD, indicating that ESR2 may influence attainment of bone mass. The aim of the study was to investigate the ESR2 gene, located on chromosome 14q linked with BMD, which demonstrates a correlation with changes in bone mass in healthy Caucasian women. The study included 675 unrelated Polish postmenopausal women, including 109 with osteopenia, 333 with osteoporosis and 233 healthy women. The women were classified into the following groups: osteopenia, osteoporosis and normal T-score. Analysis of genotype frequency for the ESR2 rs1256044 polymorphism revealed no statistically significant differences. No statistically significant differences were noted for the allele frequency. However, it is noticeable that the CT genotype occurred more often in women with osteopenia (50.4%, OR = 1.14) and osteoporosis (54.7%, OR = 1.33) than controls (47.7%). There were statistically significant differences between the clinical parameters and distribution of genotypes in patients with osteopenia but not osteoporosis. ESR2 polymorphisms demonstrate minimal influence on BMD changes in women. Identification of various genes with little impact on BMD, such as ESR2, might help design a screening panel for osteoporosis risk assessment in healthy subjects.

Pharmacogenomics of multifactorial diseases: a focus on psoriatic arthritis

This review will outline the current pharmacogenomics knowledge about psoriatic arthritis with a special attention to the perspectives and the challenges for its implementation in the clinical practice. To date, different drugs have been developed to contrast the symptoms and the progression of psoriatic arthritis. However, patients have shown high variability of drug response in relation to their genetic makeup. In this context, the advances made in the knowledge and the potentialities of genome-drugs associations paved the path for the development of a precision medicine. In fact, these associations may be successfully combined with the environment information to provide new strategies able to prevent and improve the disease management as well as to enhance the patients quality of life.

ESR1 polymorphisms and statin therapy: a sex-specific approach

Lipid-lowering therapy has shown a high degree of variability in clinical response and there is evidence that the variability in drug response between individuals is due to genetic factors. Thirteen single nucleotide polymorphisms (SNPs) within the ESR1 gene were evaluated with basal lipid and lipoprotein levels, as well as response to lipid-lowering therapy, in 495 hypercholesterolemic individuals of European descent receiving simvastatin or atorvastatin. Significant associations were detected between rs4870061 (P=0.040, corrected P-value (PC)=0.440), rs1801132 (P=0.002, PC=0.022) and the SNP rs3020314 (P=0.013, PC=0.143) with triglyceride (TG) baseline levels. The rs4870061 was also associated with high-density lipoprotein cholesterol (HDL-C) baseline levels (P=0.045, PC=0.495). Regarding statin efficacy, rs2234693 C/C was associated with greater HDL-C increase (P=0.037; PC=0.407) and rs3798577 T allele was associated with greater total cholesterol (TC) reduction (P=0.019; PC=0.209) and greater TG reduction (P=0.026; PC=0.286). These associations suggest that ESR1 polymorphisms are in part responsible for the TC, HDL-C and TG variation levels and this effect may be sex-specific.

Influence of estrogen receptor α polymorphisms on bone density in response to habitual exercise in Japanese postmenopausal women

Estrogen receptor α (ER α) is one of candidate genes for osteoporosis. This study examined the influence of ER α gene, PvuII, and XbaI genotypes on bone density of calcaneus in response to habitual exercise. ER α polymorphisms were detected using PvuII and XbaI restriction enzymes in 316 Japanese postmenopausal women. The bone density was significantly lower in the women carrying PP, pp, or xx genotype without habitual exercise than in the age-matched women without those genotypes. The women carrying Pp genotype without habitual exercise had normal bone density compared to those without Pp genotype. The women carrying PPxx or ppxx polymorphism without habitual exercise had low bone density compared to those with habitual exercise. Thus, the reduction of bone density was attenuated in the women carrying PPxx or ppxx with habitual exercise. In addition, habitual exercise was highly effective for the bone density in the women carrying xx homozygote. These findings indicate that analyses of XbaI and PvuII polymorphisms of ER α may be useful to predict the effect of exercise on bone density, and habitual exercise attenuates the reduction of bone density in women with some genotypes.

Association between single nucleotide polymorphisms of the estrogen receptor 1 and receptor activator of nuclear factor kappa B ligand genes and bone mineral density in postmenopausal Taiwanese

OBJECTIVE

To investigate the relationship between single nucleotide polymorphisms (SNPs) of the genes encoding the estrogen receptor 1 (ESR1) and the receptor activator of nuclear factor kappa B ligand (RANKL) and bone mineral density (BMD) in postmenopausal Taiwanese.

MATERIALS AND METHODS

Five ESR1 SNPs and three RANKL SNPs in 467 women were genotyped. Results of genotyping were correlated with BMD that had been adjusted for body mass index (BMI), age, and years after menopause.

RESULTS

Those with the ESR1 Crs1884054 allele were found to have a lower BMD at LS2-4/Lateral view (p = 0.005 and permutated p = 0.046), and those with the ESR1 haplotype Trs2234693-Ars922996 had a higher risk for low BMD also at LS2-4/Lat (OR = 1.8, 95% CI = 1.1-2.9). In addition, women without the RANKL haplotype Grs2148072-Crs2200287-Grs922996 had a higher risk for low BMD at LS1-4/AP (OR = 2.09, 95% CI = 1.21 ∼ 3.64). Stratification analyses revealed that those with ESR1 AArs1884054 and RANKL Ars2148072 (p = 0.032) or RANKL Trs2200287 (p = 0.007) had a lower BMD at LS1-4/AP.

CONCLUSION

Genotypes of these SNPs of ESR1 and RANKL may help us predict the osteoporosis risk in menopausal women.

Indications of clinical and genetic predictors for aromatase inhibitors related musculoskeletal adverse events in Chinese Han women with breast cancer

Background

Women with breast cancer treated with aromatase inhibitors (AIs) may experience musculoskeletal symptoms that lead to discontinuation of effective therapy. The purpose of the current study is to evaluate the clinical and genetic predictors for AIs-related musculoskeletal adverse events(MS-AEs).

Methodology and Principal Findings

We recruited 436 postmenopausal Chinese Han women receiving adjuvant AIs therapy for early-stage hormone-sensitive breast cancer. Patients completed a self-administered questionnaire assessing the presence of musculoskeletal symptoms that started or worsened after initiating AIs. 27 single nucleotide polymorphisms (SNP) of ESR1, ESR2 and PGR were analyzed by Sequenom MassARRAY assays and /or PCR-based TaqMan assays.Of the 436 enrolled women, 206 cases experienced musculoskeletal symptoms.Patients who received taxane chemotherapy were more than two times more likely than other patients to have AIs-related MS-AEs. Genetic assay had showed that only two ESR1 SNPs, rs2234693 and rs9340799 were associated with AIs-related MS-AEs.TT genotype and the T allele in rs2234693 was statistically significantly lower in AIs-Related MS-AEs group than controls (P = 0.001; P = 9.49E-7). The frequency of AA genotype and the A allele in rs9340799 was higher (P = 2.20E-5; P = 3.09E-4).

Conclusions and Significance

Our results suggested that prior taxane-based chemotherapy was the clinical predictor, while rs2234693 and rs9340799 were the genetic predictors for AIs-related MS-AEs.

Susceptibility genes for osteoporotic fracture in postmenopausal Chinese women

To identify the susceptibility genes for osteoporotic fracture in postmenopausal Chinese women, a two-stage case-control association study using joint analysis was conducted in 1046 patients with nontraumatic vertebra, hip, or distal radius fractures and 2303 healthy controls. First, 113 single-nucleotide polymorphisms (SNPs) in 16 potential osteoporosis candidate genes reported in recent genomewide association studies, meta-analyses studies, large-scale association studies, and functional studies were genotyped in a small-sample-size subgroup consisting of 541 patients with osteoporotic fractures and 554 healthy controls. Variants and haplotypes in SPTBN1, TNFRSF11B, CNR2, LRP4, and ESR1 that have been identified as being associated with osteoporotic fractures were further reanalyzed in the entire case-control group. We identified one SNP in TNFRSF11B (rs3102734), three SNPs in ESR1 (rs9397448, rs2234693, and rs1643821), two SNPs in LRP4 (rs17790156 and rs898604), and four SNPs in SPTBN1 (rs2971886, rs2941583, rs2941584, and rs12475342) were associated with all of the broadly defined osteoporotic fractures. The most significant polymorphism was rs3102734, with increased risk of osteoporotic fractures (odds ratio, 1.35; 95% confidence interval [CI], 1.17-1.55, Bonferroni p = 2.6 × 10(-4) ). Furthermore, rs3102734, rs2941584, rs12475342, rs9397448, rs2234693, and rs898604 exhibited significant allelic, genotypic, and/or haplotypic associations with vertebral fractures. SNPs rs12475342, rs9397448, and rs2234693 showed significant genotypic associations with hip fractures, whereas rs3102734, rs2073617, rs1643821, rs12475342, and rs2971886 exhibited significant genotypic and/or haplotypic associations with distal radius fractures. Accordingly, we suggest that in addition to the clinical risk factors, the variants in TNFRSF11B, SPTBN1, ESR1, and LRP4 are susceptibility genetic loci for osteoporotic fracture in postmenopausal Chinese women.

Interaction between ESRα polymorphisms and environmental factors in osteoporosis

We hypothesized that environmental factors might affect the relationship between genetic predisposition and the risk of bone mineral density (BMD) loss. Cases were 114 Japanese women with a confirmed diagnosis of postmenopausal osteoporosis and controls were 171 general Japanese women. Genetic risk of SNPs in the estrogen receptors was analyzed by a case-control study. The interaction between gene and environmental factors for osteoporosis were assessed by a case-only design. Significant increases in osteoporosis risk were observed with minor alleles of rs2077647 located in the first exon and rs2234693 located in the first intron of estrogen receptor α (ESRα). Haplotype CC at these risk SNPs was strongly associated with osteoporosis risk (odds ratio [OR] =  3.15, 95% confidence interval [CI] = 1.83-5.41). There was a statistically significant interaction between haplotype CC and alcohol drinking; moderate alcohol consumption decreased genetic risk of osteoporosis (OR  =  0.22, 95%CI  =  0.05-0.83).

Estrogen receptors α and β have different gender-dependent effects on the adaptive responses to load bearing in cancellous and cortical bone

To determine the effect of estrogen receptors (ER) α and β on bones' adaptive response to loading, we subjected the right tibiae of mice lacking ERα or ERβ activity to either axial loading or to disuse. Adaptive changes in architecture were assessed by comparing differences between the right (treated) and left (control) tibiae in these genotypes as assessed by microcomputed tomography. In female ERα(-/-) mice, the net-osteogenic response to loading was lower in cortical bone compared with their wild-type littermates (11.2 vs. 20.9% in ERα(+/+)), but it was higher in both cortical and cancellous bone of male ERα(-/-) mice (cortical 20.0 vs. 4.6% in ERα(+/+); cancellous 30.0 vs. 5.3% in ERα(+/+), P < 0.05). In ERβ(-/-) male and female mice, the net-osteogenic response to loading was higher in cortical bone (males 10.9 vs. 3.9% in ERβ(+/+); females 18.5 vs. 15.8% in ERβ(+/+), P < 0.05) but no different from controls in cancellous bone. The bone loss in response to disuse was less in cancellous bone of ERα(-/-) mice than in controls (-15.9 vs. -21.3%, respectively, P < 0.05) but no different at any other site or between any other groups. Our conclusion is that functional ERα enhances the net-osteogenic response to loading in cortical but not cancellous bone in female mice but reduces it in males. ERβ decreases the response to loading in cortical bone of males and females but has no effect in cancellous bone. Bone loss due to disuse in cortical bone is unaffected by ER status, but in cancellous bone, functional ERα contributes to greater disuse-related bone loss.

Serum estradiol levels are not associated with urinary incontinence in midlife women transitioning through menopause

OBJECTIVE

We evaluated the relationship between annually measured serum endogenous estradiol and the development or worsening of stress and urge incontinence symptoms during a period of 8 years in women transitioning through menopause.

METHODS

This is a longitudinal analysis of women with incontinence in the Study of Women's Health Across the Nation, a multicenter, multiracial/ethnic prospective cohort study of community-dwelling women transitioning through menopause. At baseline and at each of the eight annual visits, the Study of Women's Health Across the Nation elicited the frequency and type of incontinence using a self-administered questionnaire and drew a blood sample on days 2 to 5 of the menstrual cycle. All endocrine assays were performed using a double-antibody chemiluminescent immunoassay. We analyzed the data using discrete Cox survival models and generalized estimating equations with time-dependent covariates.

RESULTS

Estradiol levels drawn at either the annual visit concurrent with or previous to the first report of incontinence were not associated with the development of any (hazard ratio, 0.99; 95% CI, 0.99-1.01), stress, or urge incontinence in previously continent women. Similarly, estradiol levels were not associated with the worsening of any (odds ratio, 1.00; 95% CI, 0.99-1.01), stress, or urge incontinence in incontinent women. The change in estradiol levels from one year to the next was also not associated with the development (hazard ratio, 0.98; 95% CI, 0.97-1.00) or worsening (odds ratio, 1.03; 95% CI, 0.99-1.05) of incontinence.

CONCLUSIONS

We found that annually measured values and year-to-year changes in endogenous estradiol levels had no effect on the development or worsening of incontinence in women transitioning through menopause.

The ESR2 AluI gene polymorphism is associated with bone mineral density in postmenopausal women

Multiple factors may contribute to the pathogenesis of postmenopausal osteoporosis including environmental, life-style and genetic factors. Common variants in ESR2 gene encoding for ER-beta, highly expressed in bone tissue, have recently been proposed as candidates for affecting bone phenotype at the population level, particularly in postmenopausal women. In this study, we examined the genetic background at ESR2 AluI (rs4986938, 1730G>A) locus in 89 osteopenic, postmenopausal women (age range 49-56 years) together with BMD at lumbar spine and femoral neck sites as well as variations in plasma levels of bone metabolism and turnover markers. Genotyping for ESR2 G1730A polymorphism showed that the frequency of A mutated allele accounted for 0.4 in our cohort of postmenopausal women; moreover, the GA1730 heterozygous individuals were the most represented (50.6%) compared with GG (37.8%) and AA homozygous ones (14.6%). A regression analysis showed that lumbar spine BMD values were significantly associated with both ESR2 AA1730 genotype (p=0.044) and time since the onset of menopause (p=0.031), while no significant association was detected between biochemical markers and genetic background. Interestingly, 85% of patients with AA1730 genotype presented the smallest lumbar spine BMD values. These findings first indicate a worsening effect of ESR2 AluI polymorphism on lumbar spine BMD reduction in postmenopause, suggesting that the detection of this ESR2 variant should be recommended in postmenopausal women, particularly in populations with a high prevalence of ESR2 AA1730 homozygous genotype.

Genetic epidemiology of age-related osteoporosis and its clinical applications

Osteoporosis is an important and complex disorder that is highly prevalent worldwide. This disease poses a major challenge to modern medicine and its treatment is associated with high costs. Numerous studies have endeavored to decipher the pathogenesis of this disease. The clinical assessment of patients often incorporates information about a family history of osteoporotic fractures. Indeed, the observation of an increased risk of fracture in an individual with a positive parental history of hip fracture provides strong evidence for the heritability of osteoporosis. The onset and progression of osteoporosis are generally controlled by multiple genetic and environmental factors, as well as interactions between them, with rare cases determined by a single gene. In an attempt to identify the genetic markers of complex diseases such as osteoporosis, there has been a move away from traditional linkage mapping studies and candidate gene association studies to higher-density genome-wide association studies. The advent of high-throughput technology enables genotyping of millions of DNA markers in the human genome, and consequently the identification and characterization of causal variants and loci that underlie osteoporosis. This Review presents an overview of the major findings since 2007 and clinical applications of these genome-wide linkage and association studies.

Haplotypes of intron 4 of the estrogen receptor alpha gene and hip fractures: a replication study in Caucasians

Background

Despite their great impact, few genetic association studies have used hip fractures as an endpoint. However, the association of two polymorphisms on intron 4 of estrogen receptor alpha (ESR1) with hip fractures was recently reported in a Chinese population. The aim of this study was to investigate whether such association is also present in Caucasians.

Methods

We analyzed those two SNPs and another neighbour SNP located on the exon 4 of ESR1 in 787 patients with hip fractures and 953 controls from Spain.

Results

The allelic frequencies differed markedly from those reported in Asian populations. Nevertheless, haplotypes including the rs3020314 and rs1884051 loci in intron 4 showed a significant association with hip fractures (omnibus test p = 0.006 in the whole group and 0.00005 in women). In the sex-stratified analysis, the association was significant in females, but not in males. In women, the CA haplotype appeared to have a protective influence, being present in 6.5% of the controls, but only in 3% of patients with fractures (odds ratio 0.39; 95% confidence interval 0.26-0.59; estimated population preventive fraction 3.5%). The inclusion of the rs1801132 SNP of exon 4 further increased the statistical significance of the association (odds ratio 0.17; 95% CI 0.08-0.37; p = 0.00001). Each SNP appeared to contribute independently to the association. No genotype-related differences in gene expression were found in 42 femoral bone samples.

Conclusions

This study confirms the association of some polymorphisms in the region of exon 4/intron 4 of ESR1 and hip fractures in women. However, there are marked differences in allele frequencies between Asian and Caucasian populations.

Genetics of osteoporosis: accelerating pace in gene identification and validation

Osteoporosis is characterized by low bone mineral density and structural deterioration of bone tissue, leading to an increased risk of fractures. It is the most common metabolic bone disorder worldwide, affecting one in three women and one in eight men over the age of 50. In the past 15 years, a large number of genes have been reported as being associated with osteoporosis. However, only in the past 4 years we have witnessed an accelerated pace in identifying and validating osteoporosis susceptibility loci. This increase in pace is mostly due to large-scale association studies, meta-analyses, and genome-wide association studies of both single nucleotide polymorphisms and copy number variations. A comprehensive review of these developments revealed that, to date, at least 15 genes (VDR, ESR1, ESR2, LRP5, LRP4, SOST, GRP177, OPG, RANK, RANKL, COLIA1, SPP1, ITGA1, SP7, and SOX6) can be reasonably assigned as confirmed osteoporosis susceptibility genes, whereas, another >30 genes are promising candidate genes. Notably, confirmed and promising genes are clustered in three biological pathways, the estrogen endocrine pathway, the Wnt/beta-catenin signaling pathway, and the RANKL/RANK/OPG pathway. New biological pathways will certainly emerge when more osteoporosis genes are identified and validated. These genetic findings may provide new routes toward improved therapeutic and preventive interventions of this complex disease.

Association of ER-alpha gene polymorphism with metabolic phenotypes in Chinese Hans

Recently, two polymorphisms (rs1884052 and rs3778099) of estrogen receptor alpha (ER-alpha) gene were identified as being associated with primary quantitative bone mineral density (BMD) in a genome-wide association (GWA) study in Framingham cohorts. In this study we aimed at investigating the association of rs1884052 and rs3778099, and another polymorphism (rs2234693) located at intron 1 of the ER-alpha gene with BMD, body mass index (BMI), glucose, triglyceride, and total cholesterol (CHO) levels in Chinese Hans. We recruited 425 consecutive adult volunteers who had a physical examination in the Jinan Maternity and Child Care Hospital. We did not observe significant association of rs1884052 and rs3778099 with BMD, BMI, glucose, triglyceride, and total cholesterol (CHO) levels. For rs2234693, increased levels of BMD for hip, spine or whole-body regions were consistently observed in TT/TC genotype carriers than in CC genotype carriers, although the board line significance diminished after adjusting for age and gender. However, significant association of rs2234693 with glucose and CHO levels were observed in our sample. Subjects with TC/CC genotypes were associated with an increased level of glucose (p = 0.013) and CHO (p = 0.032) levels than subjects with TT genotypes. In conclusion, we did not confirm the association of rs1884052 and rs3778099 with BMD originally discovered in a GWA study; however, we made novel discoveries that rs2234693 was associated with glucose and CHO levels in Chinese Hans.

Age-specific effects of estrogen receptors' polymorphisms on the bone traits in healthy fertile women: the BONTURNO study

BACKGROUND

Skeletal characteristics such as height (Ht), bone mineral density (BMD) or bone turnover markers are strongly inherited. Common variants in the genes encoding for estrogen receptor alpha (ESR1) and beta (ESR2) are proposed as candidates for influencing bone phenotypes at the population level.

METHODS

We studied 641 healthy premenopausal women aged 20-50 years (yrs) participating into the BONTURNO study. Exclusion criteria were irregular cyclic menses, low trauma fracture, metabolic bone or chronic diseases. Serum C-telopeptide of type I collagen (CTX), osteocalcin (OC), and N-terminal propeptide of type I procollagen (P1NP) were measured in all enrolled subjects, who underwent to lumbar spine (LS), total hip (TH) and femoral neck (FN) BMD evaluation by DXA. Five hundred seventy Caucasian women were genotyped for ESR1 rs2234693 and rs9340799 and ESR2 rs4986938 polymorphisms.

RESULTS

Although no genotype differences were found in body parameters, subjects with combined ESR1 CCGG plus ESR2 AA-AG genotype were taller than those with opposite genotype (P = 0.044). Moreover, ESR1 rs2234693 genotypes correlated with family history of osteoporosis (FHO) and hip fracture (FHF) (P < 0.01), while ESR2 AA-AC genotypes were strongly associated with FHF (OR 2.387, 95% CI 1.432-3.977; P < 0.001).When clustered by age, 20-30 yrs old subjects, having at least one ESR1 rs2234693 C allele presented lower LS- (P = 0.008) and TH-BMD (P = 0.047) than TT genotypes. In 41-50 yrs age, lower FN-BMD was associated with ESR2 AA (P = 0.0180) subjects than in those with the opposite genotype. ESR1 rs2234693 and rs9340799 and ESR2 rs4986938 polymorphisms did not correlate with age-adjusted values of OC, CTX and P1NP.

CONCLUSION

These findings support the presence of age-specific effects of ESR1 and ESR2 polymorphisms on various skeletal traits in healthy fertile women.

Genetics of osteoporosis

Osteoporosis is a frequent skeletal disorder, particularly among postmenopausal women. It affects approximately 30% of women and 12% of men above 50 years of age. It is characterized by reduced bone mass and alterations in bone microarchitecture that result in impaired bone strength and a propensity to fracture. Decreased bone mass is the consequence of an imbalance in the bone remodeling process, resulting from complex interactions between acquired and genetic factors. The former include physical activity, nutrition and other lifestyle habits, as well as the skeletal effects of some diseases and drug therapies. Genetic factors have been extensively studied during the past 15 years. We will review some important studies that exemplify the advances and the difficulties in this research field.

Polymorphisms in the estrogen receptor 1 and vitamin C and matrix metalloproteinase gene families are associated with susceptibility to lymphoma

BACKGROUND

Non-Hodgkin lymphoma (NHL) is the fifth most common cancer in the U.S. and few causes have been identified. Genetic association studies may help identify environmental risk factors and enhance our understanding of disease mechanisms.

METHODOLOGY/PRINCIPAL FINDINGS

768 coding and haplotype tagging SNPs in 146 genes were examined using Illumina GoldenGate technology in a large population-based case-control study of NHL in the San Francisco Bay Area (1,292 cases 1,375 controls are included here). Statistical analyses were restricted to HIV- participants of white non-Hispanic origin. Genes involved in steroidogenesis, immune function, cell signaling, sunlight exposure, xenobiotic metabolism/oxidative stress, energy balance, and uptake and metabolism of cholesterol, folate and vitamin C were investigated. Sixteen SNPs in eight pathways and nine haplotypes were associated with NHL after correction for multiple testing at the adjusted q<0.10 level. Eight SNPs were tested in an independent case-control study of lymphoma in Germany (494 NHL cases and 494 matched controls). Novel associations with common variants in estrogen receptor 1 (ESR1) and in the vitamin C receptor and matrix metalloproteinase gene families were observed. Four ESR1 SNPs were associated with follicular lymphoma (FL) in the U.S. study, with rs3020314 remaining associated with reduced risk of FL after multiple testing adjustments [odds ratio (OR) = 0.42, 95% confidence interval (CI) = 0.23-0.77) and replication in the German study (OR = 0.24, 95% CI = 0.06-0.94). Several SNPs and haplotypes in the matrix metalloproteinase-3 (MMP3) and MMP9 genes and in the vitamin C receptor genes, solute carrier family 23 member 1 (SLC23A1) and SLC23A2, showed associations with NHL risk.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest a role for estrogen, vitamin C and matrix metalloproteinases in the pathogenesis of NHL that will require further validation.

Estrogen receptor alpha polymorphism is associated with pelvic organ prolapse risk

Estrogen and estrogen receptors are known to play important roles in the pathophysiology of pelvic organ prolapse (POP). We investigated whether estrogen receptor alpha (ERalpha) gene polymorphisms were associated with POP risk by conducting a case-control association study in 88 women with POP and 153 women without POP. Genotypes of the ERalpha (ESR1) gene polymorphisms (rs17847075, rs2207647, rs2234693, rs3798577, and rs2228480) were determined by polymerase chain reaction, followed by restriction fragment length polymorphism analysis. There was significant difference between women with and those without POP in the distribution of the ESR1 rs2228480 genotypes evaluated. By using multivariable logistic regression, age and ESR1 rs2228480 genotype GA were significantly associated with POP risk. Although the sample size of women with POP studied is small, the present study shows that ERalpha genotype may be associated with POP risk.

Estrogen receptor alpha CA dinucleotide repeat polymorphism is associated with rate of bone loss in perimenopausal women and bone mineral density and risk of osteoporotic fractures in postmenopausal women

The association between a newly identified CA repeat polymorphism of the estrogen receptor alpha gene (ESR1) with osteoporosis was investigated. Postmenopausal women with <18 CA repeats had low BMD, increased rate of bone loss and increased fracture risk.

INTRODUCTION

Studies have shown that intronic dinucleotide repeat polymorphisms in some genes are associated with disease risk by modulating mRNA splicing efficiency. D6S440 is a newly identified intronic CA repeat polymorphism located downstream of the 5'-splicing site of exon 5 of ESR1.

METHODS

The associations of D6S440 with bone mineral density (BMD), rate of bone loss and fracture risk were evaluated in 452 pre-, 110 peri- and 622 postmenopausal southern Chinese women using regression models.

RESULTS

Post- but not premenopausal women with less CA repeats had lower spine and hip BMD. The number of CA repeats was linearly related to hip BMD in postmenopausal women (beta=0.008; p=0.004). Postmenopausal women with CA repeats <18 had higher risks of having osteoporosis (BMD T-score< -2.5 at the spine: OR 2.46, 95% CI 1.30-4.65; at the hip: OR 3.79(1.64-8.74)) and low trauma fractures (OR 2.31(1.29-4.14)) than those with >or= 18 repeats. Perimenopausal women with <18 CA repeats had significantly greater bone loss in 18 months at the hip than those with >or= 18 repeats (-1.96% vs. -1.61%, p = 0.029).

CONCLUSIONS

ESR1 CA repeat polymorphism is associated with BMD variation, rate of bone loss and fracture risk, and this may be a useful genetic marker for fracture risk assessment.

Intron 1 and exon 1 alpha estrogen receptor gene polymorphisms in women with endometriosis

OBJECTIVE

To evaluate the association of intron 1 and exon 1 polymorphisms in the estrogen receptor alpha gene (ER-alpha) with endometriosis in women.

DESIGN

Association study.

SETTING

Endometriosis Unit, Federal University of São Paulo.

PATIENT(S)

The control group consisted of volunteers older than 45 years who had no evidence of endometriosis antecedents. Two groups with the disease were evaluated: the first group had stage I or II endometriosis and the second group stage III or IV.

INTERVENTION(S)

Polymerase chain reaction (PCR) followed by digestion with HaeIII and MspI endonucleases (RFLP) were applied to detect intron 1 and exon 1 polymorphisms, respectively, in a total of 125 controls and 105 affected women.

MAIN OUTCOME MEASURE(S)

Frequency and distribution of HaeIII and MspI polymorphisms in ER-alpha.

RESULT(S)

No significant differences in the frequency of polymorphisms either in intron 1 or exon 1 of ER-alpha were found when endometriosis patients were compared with control subjects. Furthermore, the frequency of ER-alpha polymorphisms within the two different groups of patients with disease was statistically similar. The odds ratio between presence of intron 1 single-nucleotide polymorphisms (SNP) and endometriosis was 0.904, and the odds ratio between exon 1 SNP and endometriosis was 0.976.

CONCLUSION(S)

The evaluated polymorphisms were not associated with endometriosis.

Sex steroid hormone pathway genes and health-related measures in women of 4 races/ethnicities: the Study of Women's Health Across the Nation (SWAN)

We synthesized findings relating health outcomes and genetic variants of the sex steroid hormone pathway in women from the Study of Women's Health Across the Nation (SWAN) Genetics Study. The SWAN Genetics Study, a component of the longitudinal SWAN study, describes selected genetics characteristics of health-related attributes during the menopausal transition in African American, Caucasian, Chinese, and Japanese women. At baseline, SWAN recruited menstruating women aged 42 to 52 years, who were not using exogenous hormones. Immortalized cell lines were developed and genotyped in 1,538 specimens from 1,757 participants in the genetics study. Genotypes and haplotypes from 6 genes (27 single nucleotide polymorphisms [SNPs]) in the sex steroid hormone pathway were related to circulating hormone concentrations, menstrual cycle profiles, and health-related outcomes, including lipids, diabetes mellitus, depressive symptoms, measures of cognition, bone mineral density (BMD), and vasomotor symptoms. Allele frequencies and distances differed substantially in the 4 race/ethnicity-specific groups evaluated, leading to variable patterns of association with health-related measures. For example, 17HSD genotypes were highly associated with diabetes risk in Caucasian women, whereas its haplotypes were associated with diabetes risk in both African American and Caucasian women. Several SNPs were associated with multiple outcomes. ESR1 rs3798577 was significantly associated with circulating estradiol concentrations, indicators of ovarian aging, high-density lipoprotein (HDL) cholesterol, apolipoprotein A-1, insulin sensitivity, and lumbar spine BMD. CYP1A1 rs2606345 was related to estrogen metabolite concentrations, vasomotor symptoms, and depressive symptoms. Some associations were much more prominent in specific races/ethnicities; Chinese women had statistically significant relations between ESR2 rs1256030 and HDL cholesterol, lumbar spine BMD, hip BMD, and metabolic syndrome. Importantly, women in the SWAN Genetics Study were typical of women in the community-based SWAN sample. This community-based sample of women from the SWAN Genetics Study identified important genetic sex steroid hormone pathway variants in relation to measures of health status. The magnitude and breadth of these relationships should motivate further research to verify and extend the findings.